annual report 2016 People Governing Board 10 Introduction Scientific Advisory Board 11 Group Listings 12–27 Letter from the Director 4–5 Other Staff 28–29 CQT at a glance 6–7 Alumni 30–31 Introducing our new Chairman 32–33

Projects in focus Are quantum machines better than 46–49 classical ones? News When QCMC came to town 50–53 Security in the age of quantum 54–56 CONTENTS News in brief 36–39 computing Science updates 40–43 What do the data tell us? 57–59 University arts festival takes 60–61 quantum flavour

Listings Industry collaboration Education Papers 76–81 From research to the real world 64–65 Earn a PhD at CQT 70–71 Events 82–83 Future-ready cybersecurity 66–67 What comes next? 72–73 Outreach 84–85 On the cover for Singtel On the front, CQT student Nguyen Chi Huan peers into an Visitors 86–87 apparatus that can isolate and trap a single atom between A quantum random number 67 Money Matters 88–89 two mirrors. The goal is to make single photons interact generator with the atom. Such atom-photon interfaces could be a Supporters 90 building block for quantum computers, with the trapped atoms doing logic on information-carrying photons. The back photo shows a CQT lab in perspective. drafting policies for our new centre. I shall LETTER FROM not tell you any anecdotes about them, for they are very serious people today, but they stayed in touch, showing a genuine interest THE DIRECTOR in our work. The two of them redefined for me the meaning of civil service. The annual report introductions I have been One narrative leads us to the corridors of writing for the last nine years follow a well- power. The year was 2000 and Tony Tan, at Or perhaps I can tell you a story about an established pattern. I write a few opening the time Deputy Prime Minister and Minister outreach event, during which Christian sentences, bits and pieces about the for Defence, took a personal interest in Kurtsiefer explained the magic of quantum research I found exciting, something about the Millennium Conference on Frontiers interference to a Singaporean boy. The glow outreach, contacts with industry, VIP visits, in Science, at which I gave an overview of thoughtful curiosity emanating from his face an occasional joke, and a word or two about of quantum computation. My subsequent made a big impact on me. At this moment, I the future. There are many accomplishments I meeting with Tony Tan and a long over-dinner understood that no matter how many ground- could write about this year too; however, allow conversation left me confused. I was not breaking papers, patents and quantum me to deviate from my usual pattern. used to politicians talking in an intelligent contraptions we produce, there would be and persuasive way about big problems that another legacy. We can shape how the next As we approach our tenth anniversary, I would science can address. generation sees and understands the world, like to offer a few, more personal, remarks on how they solve problems and how they will how CQT happened. I can refer you to the Another narrative takes us to the hawker make good use of quantum technologies. rest of this report for details of our new results, stalls and Indian eateries that I frequented projects and people, while I turn the clock with Kwek Leong Chuan and Kuldip Singh, I can tell many more stories, big and small, back. I'd like to share some memories I first talking mostly about quantum physics. funny and sentimental, but none of them give recalled for the book 50 Years of Science in Their enthusiasm for this emerging field was a truly comprehensive answer to the question Singapore (World Scientific, 2017). contagious. The journal club they ran brought of how it all happened. It just happened and I together faculty members, including Lai Choy am so glad that it happened, for I truly believe 2016 felt like the end of an era when Lam Heng, Oh Choo Hiap and Tan Eng Chye, who we were given an opportunity to create Chuan Leong, a distinguished civil servant despite heavy admin duties, found time to something exceptional. before his retirement, stepped down as discuss science. Chair of our Governing Board. His help was It is heartening to have the incoming Chair invaluable. Building expertise here in quantum Then I can tell a story about Chan Chui Theng, of our Governing Board, Singapore’s Chief technologies required strategic decisions. He a brave woman who decided to risk her job Defence Scientist Quek Gim Pew, describe was always available to discuss them with me security to offer temporary administrative CQT as "a jewel in Singapore's R&D and nudge me in the right direction. support (now in its tenth year) to a wacky ang landscape" (see pp. 32–33). We welcome his moh talking quantum mumbo-jumbo, and also help as we do our best to keep CQT sparkling. There is no narrative, simple or embellished, about her assistant, Evon Tan, who from day that can capture the pioneering spirit of the one defied causality (things got done before days when Singapore took the first step anyone asked for them). towards becoming a quantum island. It happened in a truly quantum fashion, in more Yet another narrative must include a than one way. wonderful duo from the Ministry of Education, Benny Lee and Perry Lim, who spent days

4 Centre for Quantum Technologies Annual Report 2016 5 The Centre for Quantum Technologies is a national Research Centre of Excellence in Singapore. It brings together quantum physicists and computer scientists to conduct interdisciplinary research into the foundations of quantum theory and the ways quantum physics enables new technologies. CQT The Centre was established in December 2007 with support from Singapore’s National Research CQT scientists are pushing the frontiers of human knowledge Foundation and Ministry of Education. CQT is and the future of technology. This AT A GLANCE hosted by the National University of Singapore massive experiment controls tiny (NUS). The Centre also has staff at Nanyang quantum systems, positioning ultracold atoms close to the Technological University (NTU) and Singapore surface of superconducting circuits University of Technology and Design (SUTD). measuring less than one millimeter across. A goal of this project led by CQT's Rainer Dumke is to transfer information between the atoms and circuits.

Staff numbers Staff nationalities Budget overview Publications

7,132,726 15 40% Manpower Research 19 Asia 31 Assistants/ Principal Associates Investigators 0 < IF < 2

5% UK 1,169,352 9 N/A 4% USA 40 27 Equipments Postdocs Admin, IT Others & Research 3% IF > 10 Support 13 2% Oceania 109 4,558,050 2 < IF < 5 Other Operating Expenditure 64% 22% Core 37 Singapore 24% 5 < IF < 10 53 Europe Postgraduate students

36% Count of CQT NUS staff Nationalities of all Spending over the Publications – External as of 31 December 2016. research staff, admin 2016 calendar year. during 2016 by In addition, the Centre staff and students See pp. 88–89 for journal impact has 18 visiting staff. employed in 2016. details. factor (IF). 6 Centre for Quantum Technologies Annual Report 2016 7 PEOPLE

Meet the people behind the Centre's achievements SCIENTIFIC GOVERNING ADVISORY BOARD BOARD

Quek Gim Pew (Chairman) Artur Ekert George Loh Ignacio Cirac Umesh Vazirani • Chief Defence Scientist, Ministry of Defence • Director, Centre for Quantum Technologies • Director (Programmes Directorate), National • Director, Head of Theory Division, Max- • Director, Berkeley Quantum Computation • Lee Kong Chian Centennial Professor, Research Foundation, Singapore Planck Institute of Quantum Optics Center (BQIC), Computer Science Division, Serguei Beloussov National University of Singapore College of Engineering, UC Berkeley • CEO, Acronis • Professor of Quantum Physics, Lui Pao Chuen Atac Imamoglu • Senior Founding Partner, Quantum Wave University of Oxford • Advisor, National Research Foundation, • Head of Research, Quantum Photonics Jun Ye Capital Singapore Group, Institute of Quantum Electronics, • JILA and NIST Fellow, University of Colorado • Senior Founding Partner, Runa Capital Ho Teck Hua ETH Zurich and National Institute of Standards and • Chairman of the Board and Chief Architect, • Tan Chin Tuan Centennial Professor and Tan Eng Chye Technology Parallels Deputy President (Research and Technology), • Deputy President (Academic Affairs) and Gerard Milburn • Chairman of the Board of Trustees, Russian National University of Singapore Provost, National University of Singapore • Director, Centre for Engineered Quantum Quantum Center Systems, University of Queensland Benjamin Koh Tan Sze Wee Nicholas Bigelow • Divisional Director, Higher Education Policy • Executive Director, Science and Engineering Michele Mosca • Professor of Optics, The Institute of Optics, Division and Divisional Director, Higher Research Council, A*STAR • Deputy Director and Co-founder, Institute University of Rochester Education Operations Division, Ministry of for Quantum Computing, University of Education, Singapore Changes to the Governing Board in 2016 Waterloo Chang Yew Kong • Quek Gim Pew replaced Lam Chuan Leong as • Chairman, Industry Advisory Committee Alternate: Mr Vincent Wu Chair in November. Christophe Salomon (Information and Communications • Senior Deputy Director, Higher Education • Benjamin Koh replaced John Lim as representative • Research Director, Laboratoire Kastler Technology), Singapore Institute of Policy, Ministry of Education, Singapore from MOE in September. Brossel, CNRS Technology • Vincent Wu replaced Lee May Gee as alternate representative from MOE in August.

10 Centre for Quantum Technologies Annual Report 2016 11 Alex's group is building Christian's group compact and rugged "One of our publications was picked up by a popular implements quantum optical entanglement science news outlet and shared over 1000 times on information building systems for experiments Facebook. It seems that people care about the fate of blocks with photons and GROUPS including a satellite- atoms, with expertise in Experimental Physics borne test. The team photons." entangled sources, single Matthias Steiner is also working on photon detection and Lee Kuan Yew Postdoctoral Fellow nonlinear optics. atom–photon interactions.

Research staff Alessandro Cerè Chng Mei Yuen, Brenda Leong Xu Heng Victor Nicholas Charles Lewty Lim Zheng Jie Janet Poh Hou Shun Shi Yicheng Matthias Steiner Tan Peng Kian

Students Alexander Research staff Students Rakhitha Bandara Chandrasekara Bai Xueliang Ling Wilson Chin Yue Sum Aswin Alexander Eapen Robert Bedington Principal Investigator Lee Jianwei Tang Zhongkan Kamiyuki Brigitta Septriani Nguyen Chi Huan Tang Zong Sheng Kadir Durak Other appointments: Mathias Seidler Aitor Villar Zafra James Grieve Assistant Professor, Shen Lijiong Department of Physics, Md Tanvirul Islam Adrian Nugraha Utama National University of Tan Yue Chuan Singapore Edward Truong-Cao Yau Yong Sean

Christian Visiting Staff Kurtsiefer Antia Lamas Linares Principal Investigator

Names shown black are staff as of Other appointments: 31 December 2016 Professor, Department of Names shown grey are staff Physics, National University of who left or move into new roles Singapore during 2016 12 Centre for Quantum Technologies Annual Report 2016 13 Dzmitry's group develops methods to "2016 was eventful for me. After a long prepare, manipulate search, we finally observed the first and detect the internal states of trapped signatures of a two-photon resonance in molecular ions for our LiK-molecule experiment." spectroscopy, precision Sambit Pal measurements and Research Fellow information processing.

Research staff Dzmitry Chen Miaoqing Matsukevich Andrew Laugharn Principal Investigator Sambit Bikas Pal Tan Senmao Other appointments: Yang Anbang Assistant Professor, Department of Physics, National University of Singapore

Students Students Kai Ding Shiqian Christian Gross Dieckmann Gan Huat Chai Jaren Lam Mun Choong Mark Principal Investigator Roland Hablutzel Sambit Bikas Pal Other appointments: Associate Professor, Department of Physics, National University of Singapore

Research staff Gleb Maslennikov Kai's group carries out experiments on ultracold gases, including investigation of Fermionic gases and dipolar molecules.

14 Centre for Quantum Technologies Annual Report 2016 15 Manas' group prepares ion trap systems to "My highlight this year, even more than emulate condensed getting my degree, was observing Rabi matter and test oscillations for the first time. I finally got a fundamental physics. The team is also ‘feel’ for quantum mechanics." interested in ions for Debashis De Munshi CQT PhD Student information processing and metrology.

Research staff Tarun Dutta Noah Van Horne Liu Peiliang

Students Research staff Murray Manas Kyle Arnold Swarup Das Barrett Mukherjee Ravi Kumar Tarun Dutta Principal Investigator Principal Investigator Lee Chern Hui Noah Van Horne Eduardo Javier Paez Debashis De Munshi Other appointments: Other appointments: Arpan Roy Associate Professor, Assistant Professor, Department of Physics, Department of Physics, National University of National University of Singapore Singapore

Students Murray's group focuses Rattakorn Kaewuam on the interfacing of Zhang Zhiqiang atoms and photons via cavity QED for quantum information applications and precision metrology. The group is working on a new design of optical

16 Centre for Quantum Technologies atomic clock. Annual Report 2016 17 Research staff Wenhui's group explores Paul Condylis the coherent excitation Ew Chee Howe and manipulation of cold Gan Koon Siang Rydberg gases, aiming Christoph Hufnagel to investigate quantum Tin Nguyen many-body physics and Maria Martinez Valado Yu Deshui quantum optics in such "We have realised coherent systems. microwave-to-optical conversion via frequency Students Visiting Staff mixing in Rydberg atoms Research staff Filip Auksztol Luigi Amico this year. We look forward to Christian Gross Phyo Bawse Thibault Thomas Vogt Naveinah Chandrasekaran publishing the details." Gan Koon Siang Wenhui Li Student Alessandro Landra Principal Investigator Han Jingshan Lim Chin Chean Oon Fong En Visiting Staff Francesca Tosto Thomas Gallagher

Rainer Rainer's group is Dumke Wenhui working on hybrid Li Principal Investigator quantum systems, Principal Investigator superconducting atom Other appointments: chips, atomtronics and a Associate Professor, School Other appointments: of Physical & Mathematical portable gravimeter. Assistant Professor, Sciences, Nanyang Department of Physics, Technological University, National University of Singapore Singapore

18 Centre for Quantum Technologies Annual Report 2016 19 "This year my group and I established a new collaboration with experimentalists from Google. My first PhD paper was GROUPS also accepted in Physical Review Letters." Theoretical Physics Jirawat Tangpanitanon CQT PhD Student

Students Dimitris' group Kishor Bharti works on theoretical See Tian Feng quantum optics and Jirawat Tangpanitanon implementations of quantum information. Particular interests include quantum simulations of condensed matter and exotic physics phenomena with Research staff Dag's group studies the Dagomir photons and ions. Debasis Mondal foundations of quantum Kaszlikowski Ryu Jeonghee theory. Interests Principal Investigator include the concept of a quantum-classical Other appointments: boundary, contextuality Associate Professor, and constraints on Department of Physics, National University of quantum correlations. Singapore

Student Marek Wajs Dimitris Research staff Angelakis Victor Manuel Bastidas Valencia Visiting Staff Principal Investigator Pawel Kurzynski Other appointments: Associate Professor, School of Electronic and Computer Engineering, Technical 20 Centre for Quantum Technologies University of Crete, Greece Annual Report 2016 21 Berge's group studies "During my 3.5 years as a postdoc, I benefited what can be known from the collaborative energy at CQT. I look about a quantum forward to my future visits." system, for example Sai Vinjamapathy by quantum state Visiting Research Fellow tomography, and the theory of cold atoms in lattices.

Kwek Research staff Leong Chuan Kwek's group works on Davit Aghamalyan Berthold-Georg Principal Investigator quantum information Andy Chia Englert with an emphasis Kwong Chang Jian Other appointments: on applied systems, Nguyen Thi Phuc Tan Principal Investigator Associate Professor, National including quantum Institute of Education and Other appointments: Deputy Director, Institute of processors and Professor, Department of Advanced Studies, Nanyang simulators. Physics, National University Technological University, of Singapore Singapore

Visiting Staff & Scholars Students Chen Jingling Masahito Hayashi Ulrike Bornheimer David Hutchinson Chai Jing Hao Song Guozhu Sanjib Ghosh Sai Vinjanampathy Gu Yanwu Zhang Kejia Alexander Hue Len Yink Loong Li Xikun Jiaan Qi Seah Yi-Lin Sim Jun Yan Students Ye Luyao Research staff Tobias Florian Haug Chau Thanh Tri Hermanni Heimonen Ng Hui Khoon Thi Ha Kyaw Shabnam Safaei Frederic Leroux Shang Jiangwei Ewan Munro Martin Trappe Wei Nie

22 Centre for Quantum Technologies Annual Report 2016 23 Valerio's group bridges theory and experiment, with a particular focus on quantum thermodynamics and the usefulness of non-locality in device- independent processing.

Research staff Vlatko Michele Dall'Arno Vedral Andrew Garner Principal Investigator Mile Gu Michal Hajdusek Other appointments: Jayne Thompson Professor, Department of Physics, National University Visiting Staff of Singapore and Professor, University of Oxford, UK Tristan Farrow Rosario Fazio

Valerio Students Scarani Students Goh Koon Tong Jungjun Park Principal Investigator Alexandre Roulet Suen Whei Yeap Stella Seah Angeline Shu Sze Yi Other appointments: Wu Xingyao Professor, Department of Physics, National University of Singapore

Research staff Vlatko's group Juan Miguel Arrazola investigates topics in Cai Yu quantum information Cong Wan ranging from discord, Dai Jibo Stefan Nimmrichter an alternative measure of quantum correlation, to thermodynamics. His team also ventures into

24 Centre for Quantum Technologies quantum biology. Annual Report 2016 25 This group explores the intersection of computer science and quantum theory, including GROUPS quantum algorithms, Computer Science communication complexity, interactive proofs & quantum games.

Hartmut Research staff Klauck Han-Hsuan Lin Anupam Prakash Principal Investigator Jamie Sikora Antonios Varvitsiotis Other appointments: Naqueeb Warsi Assistant Professor, School of Physical & Mathematical Wei Zhaohui Sciences, Nanyang Technological University, Singapore

Divesh Troy Visiting Staff & Scholars Aggarwal Lee Itai Arad Principal Investigator Principal Investigator Dmitry Gavinsky Gabor Ivanyos Other appointments: Other appointments: Iordanis Kerenidis Assistant Professor, Associate Professor, School Thomas Vidick Department of Computer of Physical & Mathematical Hoeteck Wee Science, National University of Sciences, Nanyang Singapore Technological University, Zhang Shengyu Singapore

Rahul Miklos Students Jain Santha Anurag Anshu Srijita Kundu Principal Investigator Principal Investigator Priyanka Mukhopadhyay Supartha Podder Other appointments: Other appointments: Associate Professor, Senior Researcher at CNRS in Erick Purwanto Department of Computer the Institut de Recherche en Maharshi Ray Science, National University of Informatique Fondamentale Aarthi Sundaram Singapore at the University Paris Diderot, Yang Siyi France 26 Centre for Quantum Technologies Annual Report 2016 27 Exploratory Initiatives Joseph Fitzsimons Martin Kiffner Loh Huanqian CQT Robert Pisarczyk Mohamed Riadh Rebhi Kuldip Singh Fellows David Wilkowski Admin Director

Administrative Staff Choo Hiap Visiting Staff John Baez Chan Chui Theng Oh Dieter Jaksch Chin Pei Pei CQT Fellow Jose Ignacio Latorre Giam Lay Enn, Kelly Jessie Ho Other appointments: Yu Sixia Emeritus Professor, Jenny Hogan Department of Physics, Valerie Hoon National University of Lim Siew Hoon Singapore Lim Mei Yin, Valerie Lim Mui Lian, Amell Lim Ah Bee Lim Fang Eng Jacky Research staff Visiting Scholars Lai Choy Heng Norima Binte Mohamat Sarnon Georges Batrouni Wang Fei Deputy Director Resmi Poovathumkal Raju Kho Zhe Wei Wang Xinwen Evon Tan Christian Miniatura Tan Ai Leng Irene Tan Lay Hua Yvonne Toh Yeo Kwan San Timothy

Stephanie Wehner was a Research Support Cliff Cheng Too Kee Benoît Principal Investigator at CQT Bob Chia Grémaud who completed her move to Lian Chorng Wang CQT Fellow TU Delft this year. Her group Mohammad Imran at CQT has now closed, with Other appointments: Dileej Radhakrishnan Nair research staff Le Phuc Thinh, Researcher at CNRS and Ren Yaping Shalima Binta Manir and Nelly Visiting Associate Professor, Teo Kok Seng Department of Physics, Ng Huei Ying and students Akimov Volodymr National University of Jedrzej Kaniewski and Corsin 28 Centre for Quantum Technologies Singapore Pfister also leaving CQT in 2016. Annual Report 2016 29 Where in the world are they? In academia – Locally, CQT alumni are Assistant Professors at the Nanyang Technological University (NTU) and Singapore University of Technology and Design (SUTD), others have lecturing and research positions at NTU and NUS, and some are employed at A*STAR insti- CQT ALUMNI tutes. In other countries, former CQTians are at institutions including Max Planck Institutes, the University of Copenhagen, Delft University of In the academic world, students and postdocs typically move between Technology, the Universitat Autonoma de Barcelona, the University of between institutes and even countries at the end of their terms. They Oxford, Seoul National University, the University of Technology Sydney, acquire expertise and experience from different groups, bringing to each Monash University, the University of Maryland and the University of new position a richer skillset. CQT is staying in touch with the staff and Texas at Austin. students that have been members of our community. We hope that current and former CQTians will continue to support each other in their research In industry – In Singapore, CQT alumni are working at companies and careers. We’re delighted when alumni come back – sometimes just for including Singtel, Apple Inc and World Scientific Publishing. Overseas visits, other times to take new jobs. they are in companies including Google, Becker Photonik, Siemens and running their own start-ups. We surveyed CQT alumni about where they are and what they’re doing. This page shares inputs from some 111 former CQTians.

As an NUS physics undergrad, Tan Ting Rei did a final-year What kinds of work are they doing? project at CQT in Murray Barrett's group, staying on as a Research Assistant. In 2010 he left to pursue a PhD at the 75% University of Colorado, Boulder, Academic working with Nobel Laureate David Wineland at NIST. One of Ting Rei’s results with trapped 9% ions was named a top ten Science-related breakthrough of 2016 by the industry UK’s Institute of Physics. His 16% team created entanglement Others CQT will be holding a two-day conference 7–8 December between two different ion 2017 to mark the Centre’s tenth anniversary. We invite all species (Nature 528, 380 alumni to join us for this event. Watch for invitations by (2015)). Such a 'mixed-species' email and event details on quantumlah.org. gate could be a building block for quantum computers. He will join Murray's group again in

30 Centre for Quantum Technologies 2017 as a Research Fellow. Annual Report 2016 31 CQT welcomes Singapore’s After I came over to MINDEF, I mentioned to centre that harnesses quantum technology to Chief Defence Scientist, NRF and to the Permanent Secretary that CQT improve the quality of life. has done so well, the time is right that we can GROWING A JEWEL IN Mr Quek Gim Pew, as the tap it, that we create industry out of what CQT Today we are seeing companies offering new chair of the Centre’s has done. I suppose it’s because of that I got quantum-based products. We're seeing Governing Board. In this the job – it’s me and my big mouth. venture capitalists targeting companies THE R&D LANDSCAPE offering quantum-based products. We see Q&A, he introduces himself I see this as a tremendous responsibility. CQT those big players with very deep pockets and his vision has done wonderfully well. It's a challenge to aggressively pursuing quantum computing. ensure that I move it to the next level. So I'm hopeful that in 10 to 20 years we will A distinguished career in defence Tell us about your work in see the next wave of quantum-based products What vision do you have for the embedded in everyday life, and I think Mr Quek Gim Pew was appointed Chief Defence defence Scientist of the Singapore Ministry of Defence future, or plans for change? Singapore is well positioned to play a role in (MINDEF) in July 2016. Previously, he was the Chief I've been in defence ever since I started this – and this is because we have CQT. work in ’81. My background is electrical It's too early for me to say what we should Executive Officer of DSO National Laboratories from do to change. In a short span of years, I February 2004 until June 2016. Other appointments engineering. I started working as an R&D Have you been following engineer, doing signal processing, then going think CQT has made phenomenal progress. he has held in the defence technology community I think CQT stands out really as a jewel in quantum tech for a long time? include Director of R&D at the Ministry of Defence on to manage R&D. Prior to my current job I was CEO of DSO National Laboratories for 12 Singapore’s R&D landscape. So, my role, I have always been very interested in and the Deputy Chief Executive (Technology) DSTA. and in fact the role of the governing board, physics. The only reason I didn't do physics He also sits on various boards of organizations, years. That is essentially the corporate R&D lab of the Ministry of Defence (MINDEF) where I think is quite straightforward: it is really to at undergrad is because at that time in institutions and directorship of companies. see how we can facilitate and support CQT to Singapore, if you do physics you can only we undertake R&D to try to solve problems that the Singapore Armed Forces (SAF) faces. grow and develop. Also, as a very personal be a teacher. I was not particularly keen to He graduated from the National University of agenda, I would like to see whether CQT be a teacher so the closest to physics was Singapore with a Bachelor of Engineering (1st Class DSO was started in the 70s, when the SAF can be an inspiration to future generations of engineering, and the closest in engineering Hons) in Electrical Engineering in 1981, and a Master Singaporeans to come to research. to physics was electrical engineering. But I of Science (Distinction) in Electrical Engineering was still in its infancy. Our pioneer generation had foresight. It’s amazing what you can do would say the physics that we are seeing here from the Naval Postgraduate School, USA in 1986. He Based on what I have been doing in MINDEF, is way beyond my understanding, so there is is married with three children. if you focus your resources and it’s sustained for a long time – the compound investment I think for anything to grow and to succeed, a lot of reading up to do. I have asked Artur means a lot. It’s the same as in CQT. we need three key ingredients. We need for a reading list! He was appointed Chair of CQT’s Governing Board the environment that brings the people, the with effect from 13 November 2016. How did you come to be leadership to organise the resources that are What do you do in your leisure available and the committed and supportive time? appointed as the CQT Chairman? stakeholders that will provide long-term Well, it so happened that from when I was in funding. Today I think we have very strong There are a few things I do other than reading "I see this as a tremendous responsibility. DSO, I was always very interested in working elements in all three and this puts CQT in a up. My wife is very much on the arts side – with academics to multiply our resources healthy condition. she paints and does calligraphy – so I will join CQT has done wonderfully well. It's a and in how future advances in science and her for exhibitions and events. I’m an armchair challenge to ensure that I move it to the technology will change the way the SAF I hope that CQT will continue to distinguish critic. Over the past ten years, I have also taken up tai chi as a form of exercise, and I’m next level." operates. I was looking at the universities, at itself as a centre that advances our the National Research Foundation (NRF) and fundamental understanding of quantum intrigued by the ideas behind it. I’m studying it at A*STAR. CQT obviously stands out. physics while at the same time being a when I have time.

32 Centre for Quantum Technologies Annual Report 2016 33 NEWS

Image credit: Michael Manomivibul

Digest our year's highlights in bite-sized stories

34 Centre for Quantum Technologies Annual Report 2016 35 NEWS

IN BRIEF Image credit: dag the dogg Alumnus back as NRF Dance, music and CQT’s Director elected Many-worlds fiction Fellow drama given quantum Fellow of the Royal won Quantum Shorts Mile Gu, formerly a CQT Research twist Society What if checking for monsters Fellow, was one of seven CQT was the Creative Partner In April, CQT's Director Artur under your bed doomed a scientists to be awarded the of The NUS Arts Festival Ekert was named a Fellow parallel you to a grisly end? A prestigious National Research 2016, “Wonder", presented by of the Royal Society, the story exploring the ethics of the Foundation (NRF) Fellowship NUS Centre for the Arts. The oldest scientific academy in many worlds interpretation won in 2016. He won the five-year two-week festival in March continuous existence. Highlights CQT’s international contest for fellowship for a project bringing explored the intersection of of the society's history include flash fiction inspired by quantum together complexity and science, technology and the publishing Isaac Newton's physics. The four winners, quantum science: "Enhancing arts over 30 performances by Principia Mathematica and announced in April, included two the Efficiency of Modelling and NUS students and professional approving Charles Babbage's youth entries. CQT’s Quantum Visiting Prof honoured Simulating Complex Systems artists. The collaboration saw CQT delivered first Difference Engine. Artur said “the Shorts competition series has twice via Quantum Mechanics". He CQT researchers working with industry workshop Royal Society has been doing alternated between calls for This year CQT Visiting Research joined the Complexity Institute of arts students, choreographers The commercial potential of interesting and heroic things fiction and film since 2012. It is Professor Masahito Hayashi was Nanyang Technological University of Indian and Chinese dance quantum technologies makes since its inception in 1660, and run with media partners Scientific awarded the Japan Academy as Nanyang Assistant Professor and with an orchestral ensemble companies keen to learn more. I am keen to contribute to its American and Nature. 2016’s call Medal and announced as an and the Centre for Quantum (read more at pp. 60–61). CQT is helping to meet this mission, which is to promote for film entries was supported by IEEE Fellow. The Japanese Technologies as Research need. In March this year, CQT excellence in science and to scientific partners and screening prize gives "formal recognition to Assistant Professor in February. researchers delivered a one-day encourage the development and partners in five countries – with outstanding young researchers” workshop on practical quantum use of science for the benefit of results to come in 2017. and was presented in February technologies to staff of ST humanity." at a ceremony attended by their Electronics (Info-Security) Pte Imperial Highnesses Prince Ltd, a subsidiary of Singapore and Princess Akishino. His IEEE Technologies Electronics Limited. Image credit: Michael Manomivibul Fellowship, beginning January ST Electronics is a provider 2017, is “for contributions to of information communication Shannon theory, information- technologies founded in 1969 theoretic security, and quantum and having more than 5000 information theory”. Masahito employees. is on the faculty of Nagoya University, Japan, and spends up to half of each year in Singapore. 36 Centre for Quantum Technologies Annual Report 2016 37 CQT researcher selected Quantum pioneer made 13 CQT students earned Youth met quantum at Meeting focused on for Nobel meeting Emeritus Professor their doctorates Generation Q Campamp quantum engineeringg CQT’s Dai Jibo was one of 387 CQT Fellow Oh Choo Hiap At the NUS commencement in Students barely encounter Quantum researchers from outstanding young scientists was appointed NUS Emeritus July, 13 students from the CQT quantum concepts in the France and Singapore came chosen to meet with Nobel prize Professor in July after more than PhD programme received their syllabus, but new quantum together for the Quantum winners and other luminaries three decades with the University. degrees (find the details at pp. technologies could shape their Engineering Science and of science at the 66th Lindau Choo Hiap is one of the pioneers 70–71). CQT also congratulated futures. That's why CQT brought Technologies Symposium held in Nobel Laureate Meeting in of quantum information in Md. Tanvirul Islam who Generation Q Camp back for November at NUS. The week- Germany in July. Jibo's invitation Singapore. As head of the NUS completed his PhD with the NUS a second year for students to long conference featured over 30 followed a lengthy national and Physics Department from 2000 to School of Computing and Tan explore the foundations and speakers across topics including international selection process. 2006, he recruited researchers Peng Kian who did his PhD with frontiers of this research field. 33 nanophotonics, quantum Now a Research Fellow with CQT, who later contributed to forming the NUS Department of Physics students registered from 13 local thermodynamics, quantum he is a physics graduate of NUS International CQT. “I think ten years ago it with CQT supervisors or co- schools for the five-day workshop CQT partnered with simulation, quantum computing, and an alumnus of CQT’s PhD conference drew 300 required a little bit of courage supervisors. Pengkian was the in June that offered lectures, Singtelab graphene, spintronics and Programme. scientists and insight to bet on this newly valedictorian for his cohort at the activities and lab visits. The The NUS-Singtel Cyber Security many-body physics. CQT helped Some 300 delegates came emerging area," said CQT Director commencement ceremony. participants, mainly aged 16-19, Research and Development organise the meeting, which was to NUS for the International Artur Ekert. Choo Hiap shared were taught by over 20 of CQT's Laboratory, a $42.8 million, supported by the Institut Français Conference on Quantum Singapore's National Science researchers and PhD students. five-year research venture Singapour, the NUS Department Communication, Measurement Award with colleagues in 2006 for between the university and Asia’s of Physics and the Majulab, an and Computing (QCMC) in July. quantum research and became leading communications group, international joint research unit in It was the 13th meeting in the one of the Centre’s founding launched in October. The lab Singapore of the French national biennial series. The conference Principal Investigators in 2007. will develop techniques to detect research organisation CNRS. featured special sessions and respond to security attacks on loophole-free tests of Bell and approaches to IT systems nonlocality and on industrial that are 'secure by design'. efforts in quantum computing. The lab is under the National Industry speakers came from Research Foundation’s Corporate Google, Microsoft, D-Wave Laboratory@University scheme. Systems and the NTT Basic CQT’s Alexander Ling is leading Research Laboratory (see pp. a project worth $3.5 million to 50–53). develop quantum key distribution for Singtel’s fibre network (read more at pp. 66–67). 38 Centre for Quantum Technologies Annual Report 2016 39 Non- Markovian Mirrors Zip to the boundary < Thicker may be smarter Look into a mirror and you take for granted "We found a new way to see a difference A thick crystal can work just as well as a that the image you're seeing is reflected between the quantum universe and a thin one when it comes to making pairs of straight back at you. But when mirrors are classical one," says CQT's Dagomir correlated light particles, reported Alexander SCIENCE quantum, you can't assume a reflection is Kaszlikowski. Dag worked with other Ling’s group at CQT. A common trick instantaneous. That was the finding of CQT researchers from CQT and collaborators for making entangled photons is to use researchers led by Valerio Scarani in studying at the Jagiellonian University and Adam spontaneous parametric down-conversion UPDATES the behaviour of quantum objects (Physical Mickiewicz University in Poland to show (SPDC), which relies on the strong interaction Review A 93, 023808). More technically, that a zip program, applied to experimental of a light beam with a nonlinear crystal. The they found the ‘Markovian assumption’ data, can detect evidence of entanglement interaction causes some of the photons doesn’t hold. Calculations done without this between two particles (New Journal of in the original beam to split in half. Often assumption showed that quantum mirrors Physics 18, 035011). It does so without researchers use crystals that are less than a can be used to do experiments in cavity an assumption made in other tests of millimetre thick. The CQT team systematically quantum electrodynamics (CQED). In such entanglement. tested crystals almost 16mm thick – which experiments, an atom trapped between are cheaper and easier to handle – to find < the mirrors shows an enhanced interaction parameters that give a bright and efficient < Atoms emit superflashes Making light work Discord at play in quantum Optica 3 Quantum satellite success with light. The team will explore ideas for illumination source ( , 347). The used beta barium "I remember that it was by mistake. We had An international team including CQT Principal experimenting with mirrors in superposition or borate and a blue laser with wavelength CQT’s Alexander Ling and team reported a detector in front of the laser. We turned Investigator Vlatko Vedral built a demon that entangled states. Quantum illumination is a technique that 405nm. data from their quantum payload in space off the laser and there was this flash," says extracts work from disorder in a photonic uses entangled photons to improve the (Physical Review Applied 5, 054022) – shortly Professor David Wilkowski, CQT Visiting system (Physical Review Letters 116, 050401). signal-to-noise ratio when imaging a faint before China launched its quantum satellite Research Associate Professor at Singapore's The team's work brought to life Maxwell's object against a bright light. It may not only Micius. The CQT payload is a compact Nanyang Technological University. His team demon, proposed in a 19th Century thought be entanglement but also discord that helps, device carrying components used in quantum have since worked out how to harness the experiment. It was conceived as a provocation CQT’s Vlatko Vedral and colleagues have communication and computation, built into ‘superflash’ phenomenon they saw in their to the second law of thermodynamics – shown (New Journal of Physics 18, 043027). an NUS nanosatellite called Galassia. Having cold atoms experiment to make a sequence of the idea that a system will become more Discord is a measure of more general quantum nodes in space may be a route to optical pulses (Physical Review Letters 113, disordered over time, increasing in entropy as correlations. Whereas entanglement needs establishing a global quantum network. Since 223601 (2014) and 115, 223601 (2015)). A it tends to equilibrium. The demon meddles gentle treatment, discordant correlations the satellite launched in December 2015, data setup involving a cloud of some 100 million with a system in a way that appears to are noise-resilient. This could explain why sent back show it is making pairs of correlated Strontium atoms generated high-intensity reduce entropy. With modern experimental quantum illumination works even when the photons as expected. The device is a first step pulses at a rate of 400kHz with high efficiency. techniques, researchers have been able to ambient light is bright enough to destroy in a roadmap calling for a series of launches The discovery could lead to new technology build Mawell's demons in a few setups. These Record correlations all entanglement. The team calculated that of devices of increasing capability. “Their for telecoms and other applications. The experiments carried out by collaborators at the the amount of discord that survives the experiments will pave the road to secure researchers have submitted a patent University of Oxford, UK, captured work in a CQT theorists contributed to showing that a illumination process is exactly related to quantum communication and distributed application on the approach. capacitor thanks to the demon choosing how cloud of ultracold Rubidium atoms exhibits the performance advantage of quantum quantum computation on a global scale,” to direct incoming light pulses. Bell correlations – the ‘non-local’ links that can illumination. said Artur Ekert, co-inventor of quantum exist only in the quantum world. CQT’s Jean- cryptography and CQT’s Director. Daniel Bancal and Valerio Scarani worked with experimentalists at the University of Basel in Switzerland to make the observation. The result smashes a size record. The team used a new approach to detect the correlations in clouds of some 480 atoms trapped above a microchip (Science 352, 441). Previously the biggest system in which such correlations had 40 Centre for Quantum Technologies been measured was 14 ions. Annual Report 2016 41 Topological transport < Super-resolution imaging < Security beyond encryption CQT's Dimitris Angelakis and his collaborators A novel imaging technique that beats Covert communication is when a message proposed a scheme to move groups of Rayleigh’s criterion was verified in the is sent in a way that is undetectable – it’s interacting quantum particles. The idea labs of Alexander Ling’s group. The team not only that an eavesdropper can’t decode is an example of Thouless pumping, carried out proof-of-principle experiments the message, but they can’t even tell it invented by 2016 Physics Nobelist David J. to test ideas from their NUS colleague is there. CQT’s Valerio Scarani and Juan Thouless. The topology of fields transports Mankei Tsang and his coauthors. For over Miguel Arrazola became the first to consider the quantum particles similar to the way 100 years, people accepted Rayleigh’s protocols for covert quantum communication, that an Archimedes' screw pump moves criterion as setting a minimum angular finding that it's possible to hide signals water up a hill (Physical Review Letters resolution for optical imaging. Mankei’s that are single photons or coherent states 117, 213603). One co-author is at Google team, inspired by studying quantum of multiple photons. They also propose a building superconducting circuits for quantum information, proposed ways to get round way for quantum covert communication to computing – and the team hopes to see the this limit to measure the separation of be self-sustaining, exploiting quantum key idea implemented in similar hardware. two close light sources. Alexander’s distribution (Physical Review Letters 117, group first learned about the team’s work 250503). "People in the field of quantum < < when Mankei gave a seminar at CQT < communication are hungry for new ideas. A simple trap Error-free transition Games at the quantum in November 2015. "This is our fastest The rise and fall of a photon When we put this paper out, many people Quantum experiments can be very measurements boundary ever paper from concept to result," says A close look at the most fundamental were interested," says Juan Miguel. complicated, meaning scientists are always Physicists are interested in measuring Barium The mathematics of quantum physics Alexander (Optics Express 24, 22004). interaction between light and matter – the on the lookout for techniques to simplify their atoms because calculations suggest Barium describes what particles can do, but what The paper’s first author is CQT PhD absorption of a single photon by a single machines. CQT’s Kai Dieckmann and group will show atomic parity violation, an asymmetry principles guide it? Researchers think that student Tang Zhong Sheng (pictured). atom – revealed that photon shape has a role members found one such trick, describing that may point to physics beyond the Standard studying the quantum boundary, the limits of to play. CQT’s Christian Kurtsiefer and his a way to achieve with one optical trap what Model. Barium is also an astronomical puzzle, quantum behaviour, may lead to answers. In group members carefully shaped infrared would usually take two or more. The team showing up in larger than expected quantities work published in 2016 (Physical Review A photons, which they shone one at a time showed that a ‘crossed optical dipole trap’ in some kinds of stars. Manas Mukherjee and 94, 022116), CQT researchers collaborated onto a Rubidium atom. We don't often think can not only contain a cloud of atoms but his group members measured the transition with colleagues from University of Science of photons as being spread out in time and also transport it. The trap, made by crossing probabilities of Barium’s decay from an and Technology of China (pictured) to space and thus having a shape, but the ones two laser beams, holds cold atoms in the excited state into different channels (Science extend a result that characterised a point on in this experiment were some four metres bright spot where the lasers intersect. The Reports 6, 29772) with record precision. The the quantum boundary. Other researchers long. The researchers found that if the photon researchers loaded 8 million lithium-6 atoms achievement rests on their invention of a novel had earlier identified that point by making a arrived dimly, from the atom's point of view, into the trap, moved them 25cm in less than a technique to eliminate systematic errors due to connection between the quantum phenomena then ended brightly, the peak probability second, and cooled them into a condensate magnetic fields. The technique should work for of nonlocality and uncertainty. "People of excitation was just over 50% higher than (Physical Review A 93, 053424). other atoms too. thought some counterexamples had killed when the photon arrived bright and had a off the idea. We have brought it back again," long, fading tail (Nature Communications 7, says CQT’s Valerio Scarani. They found new 13716). The work builds understanding for sets of boundary points that follow the same communication and computing schemes pattern. that require photons to write information into atoms.

42 Centre for Quantum Technologies Annual Report 2016 43 PROJECTS IN FOCUS

Explore the depth and diversity of CQT's contributions to science and community

Image credit: NUS Centre for the Arts 44 Centre for Quantum Technologies Annual Report 2016 45 ARE QUANTUM

MACHINES BETTER It hasn’t been overthrown, but But the thermodynamics of engines and thermodynamics is coming under new fridges is not restricted to complicated scrutiny as we enter the age of quantum mechanical systems. In 2010, for example, THAN CLASSICAL engineering. Thermodynamics is a statistical researchers in the UK published a description framework describing the average behavior of “the smallest possible refrigerator” [1], ONES? of large systems, for which modelling every comprising just three quantum bits. Two constituent is irrelevant or even impossible. fridge qubits at different temperatures interact As miniaturization reduces our machines to with a target qubit in such a way that heat is the size of a few particles and experimental effectively removed from the latter. These bits techniques give us control of those particles’ could be single atoms. individual degrees of freedom, does classical thermodynamics still apply? Knowing may Dzmitry Matsukevich’s group at CQT has help us better understand biomolecular recently realized a variant of this quantum CQT Research Fellow processes, too. absorption refrigerator with three harmonic Stefan Nimmrichter oscillators of different frequencies [2]. These CQT has seen a focused effort in this oscillators are the normal modes of motion introduces CQT's field this year. We aim to find out if we of a trapped ion, and they interact by a investigations might exploit quantum fluctuations to resonant conversion process. One phonon of overcome the limitations set by conventional the high-frequency mode can transform into into quantum thermodynamics. At the least, we want to a pairwise excitation of the other two modes, thermodynamics be able to reconcile the thermodynamic and vice versa. description with models based on quantum optics and quantum information theory. We If the oscillators are initially prepared in have set up a lecture series (see box "The independent thermal states of different quantum thermodynamic sessions") and temperatures the interaction will entangle already have some early results. them. One of the ions can then be refrigerated. This was confirmed both by long The world's smallest refrigerators are Hot and Cold months of measurement in the lab and by built with just a few particles. This graphic Thermodynamic principles such as the supporting theoretical simulations in Valerio conservation of energy and the tendency The textbook example of thermodynamics illustrates a three-ion system engineered is an ideal gas. If you have many atoms Scarani’s research group. to show cooling by Dzmitry Matsukevich's of entropy to increase underpin engineers’ in a given volume, you can describe their CQT group. design of power plants and car engines. Valerio’s group, which I am part of, has also They help chemists understand reactions and average behaviour with only two macroscopic quantities, pressure and temperature. The been thinking about heat engines. We’ve physicists model the behavior of atoms and designed a basic rotor engine model to photons. Einstein deemed thermodynamics laws of thermodynamics govern how these quantities behave. These same laws describe operate at the quantum scale that is inspired “the only physical theory of universal by car engines. Our motivation was to make a content” and was convinced “it will never be the workings of devices such as refrigerators and heat engines. direct comparison between the performance overthrown”. of the quantum and classical regime. As we’ll

46 Centre for Quantum Technologies Annual Report 2016 47 < A quantum machine inspired by the car engine. Our proposed autonomous rotor heat engine has interlocked gears providing a rotational degree of freedom, a harmonic resonator mode (green), and a cold and a hot heat bath (blue [1] N. Linden, S. Popescu, P. Skrzypczyk “How small [3] J. Roßnagel et al. “A single-atom heat engine” and red). The resonator exerts a radiation team also showed that if the calculations are done using this effective temperature, the can thermal machines be? The smallest possible Science 352, 325 (2016). pressure in proportion to its thermal excitation, refrigerator” Phys. Rev. Lett. 105, 130401 (2010). pushing on a piston that is attached to the rotor. system still respects the Carnot limit. [4] J. Roßnagel, O. Abah, F. Schmidt-Kaler, K. Singer, As the latter starts spinning, it changes the [2] G. Maslennikov, S. Ding, R. Hablutzel, J. Gan, E. Lutz “Nanoscale Heat Engine Beyond the Carnot coupling of the resonator to the hot and the cold This highlights a confusion in quantum A. Roulet, S. Nimmrichter, J. Dai, V. Scarani and D. Limit” Phys. Rev. Lett. 112, 30602 (2014). bath by opening and closing additional valves, Matsukevich, "Quantum absorption refrigerator with modulating the resonator's average excitation. thermodynamics. In some systems it’s a trapped ions" arXiv:1702.08672 (2017). [5] A. Roulet, S. Nimmrichter, J. M. Arrazola, V. Scarani The result is an accelerated clockwise rotation challenge to distinguish useful energy (work) “Autonomous Rotor Heat Engine” arXiv:1609.06011 driven by the difference in bath temperatures. from entropic energy (heat). In others, we (2016). The piston is effectively pushed down more strongly on the right, where the hot bath heats have to worry about the energetic cost of up the resonator, than on the left, where the external resources used in the design of resonator dumps heat into the cold bath. thermal machines. That’s the case in the example above, which needs a cooling laser and active injection of noise. If we exploit and entanglement. The latter are merely a quantum resources without accounting The quantum thermodynamics sessions consequence of the quantum description. for them, we can cheat our way to ad-hoc When we plunged into the murky waters of quantum thermodynamics in late quantum advantages. 2015, we didn't know all the traits and pitfalls of the field. With some rough ideas But what about quantum heat engines? on what we could work on, we started asking around, only to find many fellow Literature on heat engines is ample: there are The desire for a clean and objective theorists and experimentalists in Singapore with similar interests and similar proposals and realisations of various quantum comparison of engine performance in the questions. schemes that act as a kind of machine turning quantum and classical regime motivated our disordered thermal energy into useful work. proposal for an autonomous rotor heat engine This is how the quantum thermodynamics sessions were born in January 2016. [5]. It generates useful rotational motion solely We started a loosely regular series of talks on the topic for interested folk. People A widely acclaimed example came from from its coupling to a hot and a cold heat come not only from CQT but also from other departments in NUS, from the researchers in Germany experimenting with reservoir (see figure opposite). Singapore University of Technology and Design and from Nanyang Technological a single trapped ion. They made the motional University. state of the ion act as the working medium We analysed the performance in both of a piston engine [3]. It is periodically quantum and classical frameworks. It turns The first presentations by Juan Jaramillo (NUS Department of Physics) and heated by injecting electrical noise into out that the quantum version performs Dahyun Yum (Manas Mukherjee's group at CQT) attracted a broad audience funnel-shaped trap electrodes that keep systematically worse because it suffers from explore, it is not obvious that quantum will For our classical treatment, we replaced all and sparked fruitful discussions. Later we also invited external speakers such the ion confined in space, thereby pushing additional sources of uncertainty. as Alexia Auffèves from the Institut Néel in Grenoble, Paul Skrzypczyk from the always outperform classical. quantum operators by canonical variables the ion like a piston back and forth along a and solved the Newtonian equations of University of Bristol and NUS Visiting Professor Peter Hänggi, who gave us epic predefined trapping axis. Our work so far suggests that quantum and incisive lectures on quantum notions of work. Why so quantum? motion. The results matched the experimental advantages are not just lying on the table, Dzmitry observed cooling in his experiment, data as well as the quantum predictions – Remarkably, the team calculated [4] that it instead they require a clever, non-intuitive even outperforming them a little. By now, the sessions have become well established, both as a forum to exchange as the quantum theory predicted, but was it is possible to break the conventional Carnot use of additional resources, with the costs of new ideas and results amongst the local researchers and as a platform for invited really a quantum phenomenon? It’s tempting to efficiency limit – a hard limit on the efficiency those resources evaluated and included in talks and contributions from external speakers. say yes because we showed that entanglement What this tells us is that while the of heat engines – with the help of a squeezed the energy balance. is involved, and entanglement is quantum, investigated refrigerator model employs hot thermal reservoir. The caveat is that the but that’s too simplistic. We checked with old three-body correlations to operate, there is squeezed reservoir can be considered as school theory and got our answer. no ‘quantum advantage’ due to coherence having an effective higher temperature. The 48 Centre for Quantum Technologies Annual Report 2016 49 Programme Notes Valerio Scarani, Chair of the Local Organising Committee

All conferences in quantum information are interdisciplinary. QCMC leans towards experimental and WHEN QCMC theoretical physics, with mathematics and theoretical computer science playing a minor role. This is complementary to some of the conferences CQT has hosted in the past, such as the international workshop on Quantum Information Processing (QIP), the conference on the Theory of Quantum Computation, CAME TO TOWN Communication and Cryptography (TQC) and QCrypt, an annual conference on quantum cryptography. We had 31 invited speakers, chosen by the steering committee with a mind of balancing topics, geographical areas and seniority. Being an invited speaker to QCMC is highly recognized in the community but both the speakers and the organisers are aware that many other colleagues would have been just as deserving to be there. This gives rise to very balanced talks, with credit given where it is due. For this edition of QCMC, we had the idea of proposing two special sessions of invited speakers. The first was dedicated to three reports of loophole-free Bell tests, which in 2015 removed assumptions from tests of the nonlocality of quantum physics. These were by collaborations centered at the Delft University of Technology, the Netherlands; the University of Vienna, Austria; and the National Institute of Standards and Technology in Boulder, Colorado, US. The second special session was a series of four presentations by representatives of industrial groups that have invested in quantum technologies: Google, Microsoft, D-Wave and NTT. At each QCMC, an Award Committee recognizes two scientists for their outstanding achievements in quantum communication. This time, the committee chose Rainer Blatt, from the University of Innsbruck, Austria, and Artur Ekert – yes, our own director, but I was clearly told that the committee was international and so I shouldn’t fear any conflict of interest. The fact that Artur could not be present was turned into The International Conference entertainment with the help of my colleague Dagomir Kaszlikowski and team, who produced a very clever on Quantum Communication, video in two parts (see “The teleportation of Artur Ekert”). Measurement and Computing (QCMC) I am sure you have all been to conferences where the organisers are running around during the talks, sorting is one of the longest-standing series of out problems and filling forms. Well, at QCMC I was able to sit down and listen to all the talks, because the conferences in quantum information organisation was so perfect – and this is thanks to Evon Tan, and that’s why I invited her to tell us more (see science. Started in Paris in 1990, it has “Planning Notes”) travelled the world with four more editions in Europe, three in North QCMC by numbers America, one in Australia and four in 279 submissions Asia, including the thirteenth edition 21 accepted talks held in Singapore at NUS University 206 accepted posters Town in 2016 317 delegates 75 students

50 Centre for Quantum Technologies Annual Report 2016 51 Planning notes < Having been overseas when Evon Tan, Conference Secretariat, explains how she coordinates these big events The teleportation of Artur Ekert QCMC started, Artur announced The QCMC Award Committee selected CQT Director Artur via video link to the conference How did CQT come to host QCMC? Ekert to receive one of two awards presented at the 2016 banquet that he would be If a PI wants to bid for a conference, they will come to me and ask if we can fit the event into our schedule. Usually the answer is yes. Valerio meeting. teleporting himself to the awards presented a proposal at QCMC 2014 in Hefei, China, and it was then set that CQT would host the next conference in 2016. ceremony. Watch at youtu.be/8MaJzh7xEno How did you plan the conference? The organising committee made decisions at critical points, then trusted the secretariat team to follow up. I organised the logistics. On the science side, Valerio and the programme chair, Norbert Lutkenhaus, worked hard.

What are the things you organise? The next morning, there was < The ball gets rolling almost two years before the event date. There’s a set of basic things to get done, like getting a venue that is easily accessible a video link to Artur getting and the right size, looking for banquet places where you can show a different side of Singapore, finding hotels for the speakers and guests at the ready for the teleportation. He right budget, arranging accommodation for students, renting poster panels, making a delegate kit and so on. For registration we work with CQT’s IT had some problems with the and Finance teams. I have a checklist but every event is different and every committee has different expectations. teleportation device, because the manual was only in Italian. One of the difficult parts is that people need help with visa applications. For QCMC we were quite lucky that we managed to get all visas approved. Could Valerio help translate? Watch at How many conferences have you organised for CQT? youtu.be/FcPDzF3C07w Counting major conferences with over 300 delegates, this was the third. There was QIP in 2011, ICOLS in 2015 and then QCMC. We’ve also hosted lots of smaller conferences, workshops and schools. Do you have any tips for organising conferences? Just do what you need to do and be prepared for surprises. From the event organiser point of view, as much as you try your best to avoid problems, Murphy’s law applies. You also need a good team. We had great support at QCMC from admin staff, student and researchers. Were there surprises for QCMC? Actually everything went very smoothly, though we had one issue on the first day. It was the last talk, on many worlds theory, and we could hear voices from the PA system. We didn’t know where the sound was coming from. Later we discovered it was a briefing for another event by external organisers, and our sound systems had crossed frequencies.

Another interesting episode was the video we made with CQT’s Director Artur Ekert. As he couldn’t attend to collect his award, he had the brilliant idea to teleport himself from where he was going to be – an attempt that would be filmed. Artur recruited Dagomir Kazslikowski, our movie-making PI, < Valerio, me and Samson Tan, an undergraduate good at special effects, to make this happen. When we were thinking what to use for a teleportation The QCMC audience waited device, Valerio came up with the idea of a portable toilet. I sourced and reserved this ‘device’. Somehow, the surprises are fun memories when we for him to materialise in the look back! teleportation device on the conference stage. He didn’t. But What do you enjoy about leading the conference secretariat? we can report that he was later In this role, I am the first point of contact, and this gives me the opportunity to meet many different people, from young to old. One thing good about located in spacetime. physicists is that they are relaxed and it is fun to connect with them.

52 Centre for Quantum Technologies Annual Report 2016 53 Divesh is an expert in lattice-based Make and break cryptosystems. If you need a quantum- For Divesh, the quantum side is new. “I work SECURITY IN THE resistant scheme that can be realised with on trying to construct these cryptosystems software, he says “it’s probably the only and to break them. Before I’ve looked only at contender for now”. Quantum key distribution classical attacks. Now that I am here, I want AGE OF QUANTUM creates a key resistant to cracking by to collaborate with people to try to come up quantum computers, but requires new with new quantum algorithms,” he says. hardware. COMPUTING Lattice-based encryption makes use of a The only contender public key and a private key that describe Divesh did his undergraduate degree at the the same lattice – the keys define a repeating Indian Institute of Technology, Kanpur, then grid of points in space. Messages get hidden completed a PhD in number theory at ETH in lattices having hundreds of dimensions. Zurich in Switzerland. The public key spreads the bits through the Divesh Aggarwal lattice, the private key can recover them. The In 2015, the US National Security Agency It was during his PhD that he began to study mathematical core of the approach’s security changed its advice on cryptography. The lattices. “I was looking at different lecture is hard calculations such as the shortest agency now recommends that secrets notes in the area of theoretical computer vector problem. be protected with encryption resistant to science. There were some from Oded Regev quantum computers – just as soon as such that got me really interested,” says Divesh. “It is considered quantum safe. The question schemes exist. is whether it really is,” says Divesh. No-one Oded Regev is a Professor at the New York has yet found quick algorithms to solve the Divesh Aggarwal, appointed a Principal University’s Courant Institute of Mathematical underlying lattice problems, but nor can Investigator at the Centre for Quantum Sciences and one of the pioneers of lattice- anyone be sure they don’t exist. Technologies in 2016, is one of the scientists based crypto. Divesh joined his group as a working to come up with quantum-safe postdoc. “There I was able to pursue this and Divesh will explore what can be proven about cryptosystems. got many results,” he says. the hardness of the problem and search for possible attacks. “To find an algorithm that It has been known since the ‘90s that a large Divesh has since moved to Singapore, joining breaks this crypto would be really interesting. quantum computer could easily break public- the NUS School of Computing as an Assistant It would kill 20 years of work, but if it’s going key encryption. But it’s only recently that Professor at the same time as joining CQT. He to happen it’s good if someone from the quantum computers have come to be seen lives with his wife, infant daughter and parents research community finds out first,” he says. CQT has welcomed as an imminent threat, thanks to accelerating in NUS staff housing. “The entire environment And if the cryptosystem continues to stand two new Principal progress and investment. here – the work environment, the living strong, researchers can more confidently deploy it. Investigators in environment – everything is pretty appealing,” The timeframe to develop code-breaking he says. computer science, machines may already be clashing with exploring approaches the duration of security that governments He brings a new research direction to CQT’s and businesses may require – without collective computer science group led by to data security in a counting the years it takes to certify new PIs Miklos Santha, Rahul Jain, Troy Lee and quantum future cryptosystems. Hartmut Klauck.

54 Centre for Quantum Technologies Annual Report 2016 55 Singapore was a comfortable place for his Security boost family to settle. “My wife is from China so for The AFOSR funding supports work on WHAT DO THE us Singapore is a very good mix of cultures,” building blocks for secure quantum he says. computing. “We have been looking at ways of using quantum effects to enhance secure DATA TELL US? In 2013, Joe was awarded a prestigious classical computing,” says Joe. Moves to use fellowship from the National Research quantum systems for key distribution (see pp. CQT Assistant Professor Ng Hui Khoon and Foundation (NRF) in Singapore, bringing 66–67) is an example of how quantum and five year’s funding for him to establish his classical systems can work together. Principal Investigator Berge Englert advocate own group. Joe was also offered a faculty for a refined method of estimating quantum position at the newly-established SUTD. “It seems like there are other things we states Meanwhile Joe retained a Research Assistant might do with not very complicated quantum Professorship at CQT. The shift to being a devices, maybe requiring one or two qubits, PI makes him part of the Centre’s Executive that could add functionality or security,” Joe Fitzsimons Committee, which takes management says Joe. Early results have led to a patent Joe remembers what got him started in decisions, and gives access to CQT’s core application. quantum technologies. He was 17 when funding. he read The Code Book, a history of Joe won’t be building a quantum computer or cryptography by science journalist Simon a quantum network – he’s a theorist – but he’s Singh. The book covered the RSA algorithm, a "My feeling is that people optimistic that he’ll see them exist. “There are widely-used cryptosystem. RSA also happens vastly underestimate lots of caveats that go with the experimental results that you see mentioned in news to be vulnerable to cracking by quantum the power of quantum computer. That fact struck Joe so deeply that reports, but at the same time it's very clear it set him on the path he still follows today. technologies" that our ability to control the quantum states of matter and of light has dramatically increased “Most of what my group does and most of over the last number of years,” he says. where our funding comes from is for secure For now, Joe’s research group – numbering He hopes these technologies will bring quantum computing,” says Joe, who is an 7 postdocs, 4 PhD students and a few Assistant Professor at the Singapore University applications beyond those we’re planning for, undergraduates – is supported by the NRF just as we’ve integrated computing into more of Technology and Design (SUTD). His Fellowship and a grant from the US Air Force How can you identify the properties of a quantum facets of our lives than the inventors of the state from measurements of many copies? The appointment as a CQT Principal Investigator, Office of Scientific Research (AFOSR). first computers could have imagined. method developed by Ng Hui Khoon, Berge confirmed in 2016, will start in January 2017. Englert and their colleagues calculates multi- The NRF Fellowship is focused on verification “My feeling is that people vastly underestimate dimensional error bars from noisy experimental Growing roots of quantum computations. When quantum data, taking as a prior that the data is quantum. the power of quantum technologies. We get Their ‘smallest credible regions’ for two simulated computers are crunching problems that can’t The title may be new, but Joe’s association stuck listing very specific applications that data sets are shown in this figure. Any point with the Centre goes back to 2010. That be solved any other way, how can we know if come from heavily-studied, toy problems. in the triangle can represent observed relative year he moved to Singapore to join CQT they are working properly? “We’re developing Some applications that are likely to be very frequencies, whereas only points in the circle as a Senior Research Fellow. He had just protocols that let you test that the output of stand for quantum probabilities. The star indicates promising would probably sound ridiculous at the actual state. They made two data sets by some device that is allegedly a quantum completed a fellowship at the University of the moment,” says Joe. “I would like to help simulating measurements on only 24 copies of this Oxford in the UK, where he’d done his PhD computer is correct, that it's consistent with discover some of the applications we haven’t state, then used the data to generate the two sets too. He is originally from Ireland. quantum mechanics” explains Joe. of contours. The central regions are 50% likely to thought of yet.” contain the state, the outer regions 90% likely.

56 Centre for Quantum Technologies Annual Report 2016 57 Quantum experimenters, like classical ones, the desiderata are a reliable estimate of the triangle in the simple situation illustrated on 95% credibility does have a 95% chance of information tasks beyond tomography. (See [1] J. Shang, H. K. Ng, A. Sehrawat, X. Li, and B.-G. Englert, "Optimal error regions for quantum state make measurements and take data to find quantity of interest, a meaningful statement the preceding page. The possible values containing the actual probabilities. The SCRs Ref. 4 for a publicly available repository New J. Phys. 15 out about their systems. Imagine you need a of the uncertainty in the estimate, as well of the quantum-mechanical probabilities, are regions around the ML estimator. of existing samples, and also the code for estimation" , 123026 (2013). ten-qubit state of certain properties to run a as a consistent approach to incorporating however, are a subset of this simplex, such generating more.) [2] J. Shang, Y.-L. Seah, H. K. Ng, D. J. Nott, and B.-G. computation. How can you be sure that your prior information from given premises and, as the disk inscribed into the triangle. It can We find these regions by refining our prior Englert, " Monte Carlo sampling from the quantum state system is producing that state? A standard perhaps, previous experiments. easily happen that the relative frequencies information about the identity of the quantum In many situations, especially for high- space. I" New J. Phys. 17, 043017 (2015). approach is to make many copies and, are not quantum-permissible probabilities. state, becoming more confident of the states dimensional systems, one seeks not [3] Y.-L. Seah, J. Shang, H. K. Ng, D. J. Nott, and B.-G. through measurements on those copies, infer Consider that we probe independently and The assignment p^j = fj then yields an estimate consistent with the observed data, and information about the full state, but the values Englert, " Monte Carlo sampling from the quantum state the starting properties. This is the process of identically prepared copies of the system, that flies in the face of the most basic of consider the inconsistent ones as less likely. of a few properties of interest. After all, the space. II" New J. Phys. 17, 043018 (2015). quantum tomography. getting one measurement outcome for each prior information: that the data comes This refinement is rigorously carried out within state of a ten-qubit system, say, has more [4] http://www.quantumlah.org/publications/software/ from measuring a quantum system. There the Bayesian framework by the update of the than a million parameters and it is impossible, QSampling/ But how should the inference happen? It’s an “the quantum experimenter are even cases in which the law of large prior-before data-probability distribution to the not to mention pointless, to completely [5] X. Li, J. Shang, H. K. Ng, and B.-G. Englert, important and rich question. After studying faces a tougher job than numbers won’t help, for example where the posterior-after data-distribution. characterize the system. Besides, even if "Optimal error intervals for properties of the quantum the statistical techniques, we encourage circle touches the triangle. full characterization is feasible, if the focus state" arXiv:1602:05780v3 (2016). more of our fellow quantum physicists to the classical experimenter By contrast, popular methods for constructing is on a particular property-computable as a move away from frequentist statistics to in acquiring reliable Clearly, we need a better way of determining error regions produce sets of ‘confidence function f(p) of the quantum probabilities, Bayesian methods, which take into account estimates for the probabilities from the relative regions’. These have the defining property the best estimate of the property value from prior knowledge. In this article, we lay out information” frequencies. Such strategies are available, that if we repeat the experiment very often, the data is usually not given by putting into why. We also introduce the approach we among them the so-called maximum- and each time we identify the confidence the function the estimated probabilities. have developed for calculating uncertainties copy. The sequence of observed outcomes likelihood (ML) estimation, where one sets region for the fj s of the observed data, then Instead, best use of the data calls for a direct in quantum state estimation, for which we form the data. We infer the quantum- the probabilities to match those for the state 95% of these regions will contain the actual estimation of f, without first estimating p. In provide open-source code that others can try. mechanical probabilities from the observed most likely, among all quantum states, to give probabilities. The individual confidence region Ref. 5, we show how to do this through an ML data, and then the quantum state of the the gathered data. Our work has focussed for the data of one run of the experiment procedure, supplemented by SCRs in the low- A naive approach system from these probabilities. on finding the best way to calculate the does not have the meaning that the actual dimensional space of property values. Arguably, the quantum experimenter faces a uncertainty in this point estimation, identifying pj s – among all permissible pj s – are inside tougher job than the classical experimenter It is tempting to simply use the relative a region in the quantum-probability space that with a 95% chance. This may be overlooked. We have taken definitive steps towards in acquiring reliable information. In addition frequency fj with which the jth outcome has a good chance of containing the actual It is more useful to identify a region in the fulfilling the list of desiderata for properly to grappling with noise fluctuations, the occurs in the data as an estimate p^j for the values. Such a region is the generalisation of quantum-probability space with a good inferring what the data tell us about quantum fundamental indeterminacy of quantum probability pj of its occurrence, that is: p^j = fj . the error bar on an estimated number, and we chance of containing the actual values. mechanical systems. We hope to see more processes means that the data are After all, the law of large numbers ensures fj speak of an error region. work adopting such Bayesian methods. There unavoidably random. Quantum physics tends to pj when many copies are measured. Crunching numbers are quantum physicists using such statistics predicts only the probabilities of occurrence However, this naive approach can be In work published in 2013 [1], we showed The identification of the SCRs for the given but many in the field do not yet see the of different outcomes. State-of-the-art dangerous. how to construct error regions that are data requires the computation of high- advantages. quantum experiments performed on fragile optimal in the following precise sense: they dimensional integrals. In Refs 2 and 3, we systems also tend to yield much fewer data Establishing credibility are the smallest regions for a pre-chosen have developed fast algorithms employing than typical of classical experiments. The possible values of the frequencies are credibility. Here, the size of a region is the Monte Carlo integration for constructing only restricted by the obvious constraints: prior chance that the actual probabilities are the SCRs. These algorithms are capable of The statistics we apply to our limited and the fj s cannot be negative and they must inside; it reflects our prior knowledge about generating high-quality samples from any fundamentally random quantum mechanical have unit sum. In technical terms, the fj s are the apparatus that prepares the quantum given distribution on the quantum-probability data must achieve a number of goals. Among points in a simplex, such as the equilateral systems before any data is taken. The space, and are useful for many other quantum smallest credible region (SCR) with, say, 58 Centre for Quantum Technologies Annual Report 2016 59 UNIVERSITY ARTS FESTIVAL TAKES Image credit: NUS Centre for the Arts Image credit: Kinetic Dance Expressions, courtesy Image credit: NUS Centre for the Arts NUS Centre for the Arts QUANTUM Quantum world Quantum visualizers Speaking about spooky through dance CQT’s Jirawat Tangpanitanon, Rattakorn action at distance Kaewuam and Poh Hou Shun worked FLAVOUR Singapore Cultural Medallion recipient Mrs together to visualise sound for a concert CQT invited award-winning science writer Santha Bhaskar, the Artistic Director for by the Asian Contemporary Ensemble. George Musser to Singapore to give a public NUS Indian Dance, raised her hand when When the ensemble performed Terry talk during the NUS Arts Festival. Back in At the invitation of the NUS Centre for the Arts, CQT was the creative partner NUS Centre for the Arts issued a call for Riley’s minimalist composition "In C" (1964), 2011, George spent two months at CQT as of the NUS Arts Festival in 2016, themed Wonder. Festival Director Sharon artists curious to explore the quantum world. microphones on individual instruments fed writer-in-residence. George is a contributing Tan said they wanted to challenge students to think “how might the study She read widely and met regularly with editor to Scientific American magazine and of quantum physics reframe our perspective to reawaken our capacity for CQT scientists Roland Hablutzel and Sai signals to a trio of ‘laser spirograph sound was then doing research for a popular book wonder?” visualizers’ built by the three experimental Vinjanampathy to dig into new ideas. “The physicists. The devices created spiralling about quantum entanglement. The result CQT offered a seminar to members of student art groups in June 2015, giving Spooky Action at Distance physicists’ experiments were an eye-opener green patterns directly from the changing was published an introduction to the quantum world and the research carried out at CQT. for me to ‘the world’ I am existing in,” she by Scientific American / Farrar, Straus and Ultimately researchers at the Centre collaborated closely in a few of the said. She chose the concept of entanglement sounds. Giroux in 2015. With the bold subtitle The festival’s 39 events, consulted on others and saw a physics flavour spread through other shows. The graphic to the left is from the festival guide. to inspire a short work of Bharatnatyam, Phenomenon That Reimagines Space and We later showed these same devices at Time – and What It Means for Black Holes, a type of classical Indian dance. Called the Singapore Maker Faire, where CQT In a feature in local newspaper the Straits Times, CQT’s Director Artur Ekert Sambhavna (probability), the piece the Big Bang, and Theories of Everything, explained why the Centre supports such art-science events. He said “The performed in 2016 featured seven dancers researchers also talked about how they the book is a deep exploration of what quantum reality that lies behind our everyday world is quite magical and full use lasers in the lab. “We have enjoyed of promise for new technologies, but people often don’t explore these ideas and original music that mixed the cosmic working as a team, solving a few challenges entanglement tells us about the nature of because they get stuck thinking, quantum physics is too hard for them. When sound of the cello with traditional flute and and communicating science to both kids spacetime. It was long-listed for the PEN / the physics appears instead as surprises in plays, film and dance, I think the drums. Sambhavna is to be developed into E.O. Wilson Literary Science Writing Award audience gets to experience a little of the excitement and wonder that we a full-length show for the 2017 festival. Mrs and enthusiastic adults,” says Jirawat. The and short-listed for Physics World's 2016 scientists feel when we do research.” design of the visualizers is documented at Bhaskar holds the honorary title of CQT www.instructables.com/id/Laser-Spirograph- Book of the Year This 11th edition of the NUS Arts Festival was held 11-26 March reaching an Outreach Fellow until April 2017. audience of around 11,000 people. CQT will be a collaborator again in events Sound-Visualizer-LSSV/ for the 2017 NUS Arts Festival: Brave New World.

60 Centre for Quantum Technologies Annual Report 2016 61 INDUSTRY COLLABORATION

Find out how we are working to realise the commercial impact of our research

62 Centre for Quantum Technologies Annual Report 2016 63 gather insights on the challenges they face to that everyone says is crazy, or have some better inform our researchers of industry pain neat device that you want to commercialise, points. come talk to us! Borrowing Peter Thiel’s idea, from his best-selling business book of 2014 Engage – How do you inform and convince about startups that have impact, we very industry players that they should take a closer much like the process of turning “Zero to look at, adopt or invest in quantum technolo- One” (pun intended). gies? This will involve proactive interaction with companies that do not have quantum I am mindful of questions about the balance technologies as a core business, but which of basic research versus applied research could benefit from its application. The NUS- in centres such as CQT. As a physics FROM Singtel Corporate Lab launched in October student, I firmly believe that researchers 2016 is a good example (see pp. 66–67), should maintain independence over their where Singtel’s interest in future-ready cyber research direction to have the freedom to go RESEARCH security systems matched our expertise in on whatever path nature leads them to. But as someone who has spent time in industry It is with great pleasure that I am re-joining “Borrowing the title of a working on products, strategy, marketing and TO THE REAL the family at CQT after more than ten years best-selling business book, the like, I also see the tangible value that a away in industry. The academic environment good product or service can bring to people has a very special meaning to me, especially we very much like the and the important role such companies play WORLD here at NUS where many mentors and process of turning 'Zero to in the value chain. I think there needs to be professors helped shaped my views of the healthy debate and constructive tension A career path comes full circle world. I worked with members of the Centre One' (pun intended)” between these two directions in order to arrive CQT welcomes Lum Chune Yang as Prior to joining CQT, Lum Chune Yang was responsible for for Quantum Technologies before the Centre at an optimal allocation of resources for CQT. the Centre’s new Head of Strategic business development activities in Asia-Pacific for SES, a even existed. So, when I came across this quantum cryptography. In other cases, we global satellite operator. In this role, he led engagements opportunity in Industry Relations at CQT, I may have to look more broadly to find a fit. I think we will have some exciting times Development, Industry Relations. He with private companies on commercial deals and was excited. For example, the team is in discussion with ahead, and I look forward to helping raise explains how he came to the role and government agencies on national satellite projects. He also a commercial telecommunications satellite CQT’s profile in the industry. In the meantime, led the market entry strategy and implementation plan for My new colleagues in the Industry Relations operator, where satellite QKD could be a let’s revel in the pleasure of finding things out, what he hopes to achieve China and was involved in internal innovation initiatives. team, Alexander Ling and Evon Tan, have value-added service for their top-end cus- and trust that the rest will follow. Before his stint at SES, he was a management consultant already made significant progress in tomers. We will be looking into other areas, with ZS Associates, based initially in the US, then in Shanghai engaging industry. I hope my experience can working with our researchers to evaluate what to help set up the company’s first office in China. In this role, complement their efforts. Going forward, our kind of companies could augment or enhance he advised MNCs on their market entry and sales strategy, as activities will have three main themes: their research. well as post-merger integration activities. Inform – Following the success of the one- Create – Quantum technology is at the Chune Yang holds an MBA from INSEAD, an MSc in Physics day seminar held in 2016 for ST Electronics leading edge of the technology curve, and from the Pennsylvania State University, and a BSc (Hons) in (see p. 37), we plan to organize more such in some cases, industry or customers may Physics from the National University of Singapore. At NUS, seminars based on themes of interest for not see its value yet. Sometimes, there are he was a research assistant at the Quantum Information different industry sectors at varying degrees no examples of use cases. We may be able Technology lab, the precursor to the Centre for Quantum of sophistication. Through these sessions to create new markets. To my colleagues at Technologies. and the dialogues that follow, we also hope to CQT, I say, if you have an idea for a startup

64 Centre for Quantum Technologies Annual Report 2016 65 security of the key by observation of the violation of a Bell Inequality, a measure of the strength of the quantum correlations. A possible FUTURE-READY outcome is that trusted QKD devices could be constructed from A QUANTUM untrusted components. CYBER SECURITY Alexander leads the project under the NUS-Singtel Cyber Security RANDOM Research and Development Laboratory, themed “Future-Ready Cyber FOR SINGTEL Security Systems”. The lab launched in October 2016 (see p. 39). NUMBER The objectives of the three-year, $3.5 million initiative are to develop a fibre-compatible quantum signal generator, characterise Singtel fiber for quantum signals and to deliver quantum signals over Singtel’s fiber GENERATOR network. CQT researchers have filed a provisional patent covering technology An interdisciplinary team of scientists, engineers and business people for fast generation of random numbers by hardware, as opposed to from CQT and Singtel is coming together to achieve these goals. algorithmic approaches. The method relies on measurement of vacuum fluctuations of the electromagnetic field. Random numbers are used in simulations and gaming. When software is used to generate ‘pseudo-random numbers’, there can be subtle patterns in the outcomes that affect the results or may be exploited. The idea is that quantum random number generators (QRNGs) avoid this problem because quantum physics says that nature is inherently random. Developed by members of the CQT quantum optics group led by Christian Kurtsiefer, the optical QRNG is described in Appl. Phys. Lett. 109, 041101 (2016). The team is in talks to license the technology.

CQT Principal Investigators Alexander Ling, Christian Kurtsiefer A first generation of QKD devices are already commercially available. and Valerio Scarani are collaborating with Singtel, Asia’s leading Using weak laser pulses approximating single photons, QKD has communications group, to bring quantum key distribution (QKD) to been demonstrated for applications including secure transmission of commercial fibre in Singapore. votes in a Swiss election, by company ID Quantique, and encryption of streaming video in a test network in Tokyo. There are numerous Advantages of using the quantum properties of light particles, photons, projects coming up, including China’s plans to operate a quantum to distribute encryption keys include that QKD is impervious to quantum network of trusted nodes between Beijing and Shanghai. computers (and all computing attacks), offers automatic symmetric key delivery, and allows detection of tampering or intrusion on the CQT has expertise in entanglement-based quantum cryptography, a communication line. The photon arrival times can also be used for clock next-generation technology that has additional security advantages. synchronisation. These include integration of the randomness generation process into the physical key distribution. It may also be possible to verify the

66 Centre for Quantum Technologies Annual Report 2016 67 EDUCATION

Join us in celebrating the successes of CQT's students and graduates

68 Centre for Quantum Technologies Annual Report 2016 69 Davit Aghamalyan Poh Hou Shun Li Xikun Ved Prakash Atomtronics: Quantum Testing the Quantum- Error Regions for Properties Efficient Delegation Congratulations Technology with Cold Classical Boundary and of the Quantum State Algorithms For Outsourcing to the graduates Atoms in Ring Shaped Dimensionality of Quantum Computations On Massive Optical Lattices Supervised by Berge Englert of 2016 Systems Data Streams CQT PhD Programme Supervised by Kwek Leong Supervised by Christian Kurtsiefer Supervised by Hartmut Klauck Chuan CQT PhD Programme CQT PhD Programme EARN A PHD AT CQT CQT PhD Programme We welcome students from all over the world to do research in Dai Jibo Tan Peng Kian quantum technologies Experimental Entanglement Stellar Temporal Intensity Witness Family Measurement Interferometry And Theoretical Aspects Of PhD Programme Quantum Tomography Co-supervised by Christian CQT offers high-quality education and supports graduate students in making original contributions to Kurtsiefer and Chan Aik Hui Phil Supervised by Berge Englert research. We accept applications throughout the year from motivated students who want to step into the NUS Department of Physics PhD Programme dynamic field of quantum technologies. We offer opportunities in experimental and theoretical physics CQT PhD Programme and in computer science. In 2016, CQT had 66 students studying under its PhD@CQT programme, which offers a generous scholarship plus allowances for travel and other expenses. Doctoral degrees are awarded by the National University of Singapore, consistently ranked among the leading universities in the world. CQT Le Phuc Thinh Ritayan Roy also accepts students funded by other sources. Find more information on the student programme and a Advances In Quantum Key An Integrated Atom Chip description of how to apply at quantumlah.org. Distribution And Quantum for The Detection and Randomness Generation Manipulation of Cold Internships Atoms Using a Two-photon Supervised by Valerio Scarani Transition CQT offers internships to students near the end of an undergraduate degree or during masters studies who are contemplating a career in research. Applications should be made directly to the PI with whom CQT PhD Programme Supervised by Bjorn Hessmo the student would like to work. A successful intern making a follow up application to the PhD@CQT programme will be given high priority. CQT PhD Programme

Md. Tanvirul Islam Ding Shiqian Jedrzej Kaniewski Jiabin You Cai Yu Protocols for Quantum Entangled Photon Pairs: Relativistic quantum Majorana Fermion in Quantum Sizes: Complexity, Networks Efficient Generation cryptography Topological Superconductor Dimension And Many-box and Detection, and Bit and Mott-superfluid Locality Supervised by Stephanie Wehner Commitment Supervised by Stephanie Wehner Transition in Circuit-qed and Hugh Anderson System Supervised by Valerio Scarani Supervised by Dzmitry CQT PhD Programme NUS School of Computing PhD Matsukevich CQT PhD Programme Programme Supervised by Oh Choo Hiap CQT PhD Programme CQT PhD Programme 70 Centre for Quantum Technologies Annual Report 2016 71 Colin Teo Having graduated in 2014 with a thesis on “Quantum Optics in Information and Control”, Colin recently made a career move – into biology. Colin joined the NUS Centre for Bioimaging Sciences in November to work on a technique known as flash x-ray imaging, which is used to deduce the shape of large molecules such as viruses. His job is verifying algorithms that calculate a molecule's structure from tens of WHAT COMES NEXT? thousands of images. It’s interdisciplinary work. “My group has people with different backgrounds. There's an electrical engineer, a mechanical A doctoral degree is just the first milestone in a young scientist’s engineer, a computer engineer and three physicists," he says. career. We look at what CQT graduates have chosen to do next Before an interest in data science led him to this new role, Colin did two quantum postdocs, first at the Institute for Quantum Optics and Quantum Information in Austria and then at the Singapore University of Technology and Design. He finds his training in quantum information useful for his job. Each 2D image is snapped of a different molecule, which is destroyed in By the end of 2016, some 41 students had graduated from the PhD the process. The molecules' orientation in each image is unknown. "The programme under CQT’s core and grant funding. What do these problem is similar to cryptography," he says. "The algorithms try to find students do with their hard-earned expertise in quantum technologies the most likely orientations for the 2D images to map to a 3D structure. and creative problem solving? Here are some of their stories. Since the orientation for each image is 'hidden' in the data, it is like trying to decrypt a message with a key buried in the message itself."

Nick Lewty Davit Aghamalyan is back. Markus Baden, a graduate CQT PhD graduate Nick is now a Hardware Engineer for Apple in After he finished his PhD in in 2014, is now a consultant Singapore, developing devices to go into the company’s products. 2015, he did a postdoc at the in Zurich Switzerland. He “The CQT PhD gives graduates the skillsets they need to compete in A sampling University of Rennes in France. works at d-fine AG, an IT, risk industry at a high level,” says Nick. He was hired by Apple in 2016 after of other CQT He returned to Singapore in management and financial an intense interviewing process that included technical exams. 2016 to take up a postdoctoral consultancy. graduates’ paths position at CQT. Nick completed his PhD in one of CQT’s ion-trapping groups in 2014. He then worked at the Centre as a postdoc in quantum optics, before looking for jobs in optical engineering in industry. He found the Apple position through an advert online.

At CQT Nick was involved in designing, building and programming Han Rui who completed her Ved Prakash, who defended Tan Kok Chuan Bobby, a complicated setups for precision measurements. “I use a lot of what I PhD in 2012, is a postdoc at the his thesis in 2015, first joined graduate in 2014, is a postdoc learnt in the lab. It’s not exactly the same tools, but the lab skills,” he Max Planck Institute for the Singapore’s Ministry of Defence at Seoul National University in says. This includes doing a lot of programming for the equipment they Science of Light in Erlangen, as a data scientist. He is moving South Korea. Germany. She makes regular to Singtel in a data scientist use. Nick can’t say what he works on for Apple. What he can say is “I am return trips to CQT to continue role in 2017. really enjoying it.” Nick is married to a Singaporean journalist. They live collaborations. together with their two adopted cats.

72 Centre for Quantum Technologies Annual Report 2016 73 LISTINGS

Read on for a comprehensive review of our papers and events in 2016

74 Centre for Quantum Technologies Annual Report 2016 75 1600 PAPERS 1400 1200 Cumulative A compositional framework for Markov An upper bound on the second order Charge-qubit-atom hybrid Correlation detection and an operational CQT Publications 1000 processes asymptotic expansion for the quantum Yu, DS; Valado, MM; Hufnagel, C; Kwek, interpretation of the Renyi mutual 800 Baez, JC; Fong, B; Pollard, BS communication cost of state redistribution LC; Amico, L; Dumke, R information IF > 1 5 < IF < 1 J. Math. Phys. 57, 33301 (2016) Datta, N; Hsieh, MH; Oppenheim, J Phys. Rev. A 93, 42329 (2016) Hayashi, M; Tomamichel, M 600 J. Math. Phys. 57, 52203 (2016) J. Math. Phys. 57, 102201 (2016) 2 < IF < 5 A new device-independent dimension Chiral quantum walks 0 < IF < 2 400 witness and its experimental Atomic properties of Lu+ Lu, DW; Biamonte, JD; Li, J; Li, H; Correlations, operations and the second Not applicable implementation Paez, E; Arnold, KJ; Hajiyev, E; Porsev, Johnson, TH; Bergholm, V; Faccin, M; law of thermodynamics 200 Cai, Y; Bancal, JD; Romero, J; Scarani, V SG; Dzuba, VA; Safronova, UI; Safronova, Zimboras, Z; Laflamme, R; Baugh, J; Vinjanampathy, S; Modi, K J. Phys. A 49, 305301 (2016) MS; Barrett, MD Lloyd, S Int. J. Quantum Inf. 14, 1640033 (2016) 0 Phys. Rev. A 93, 42112 (2016) Phys. Rev. A 93, 42302 (2016) 2007 2008 2009 20102 011 2012 2013 2014 2015 2016 2017 A quantum approach to homomorphic Covert Quantum Communication encryption Atomic Response in the Near-Field of Coherent chemical kinetics as quantum Arrazola, JM; Scarani, V Duality in entanglement of macroscopic Evaluation of entanglement measures by Fast graph operations in quantum Geometric phases causing lifetime Tan, SH; Kettlewell, JA; Ouyang, YK; Chen, Nanostructured Plasmonic Metamaterial walks. I. Reaction operators for radical Phys. Rev. Lett 117, 250503 (2016) states of light a single observable computation modifications of metastable states of L; Fitzsimons, JF Aljunid, SA; Chan, EA; Adamo, G; Ducloy, pairs Lee, SY; Lee, CW; Kurzynski, P; Zhang, CJ; Yu, SX; Chen, Q; Yuan, HD; Zhao, LM; Perez-Delgado, CA; hydrogen Sci. Rep. 6, 33467 (2016) M; Wilkowski, D; Zheludev, NI Chia, A; Tan, KC; Pawela, L; Kurzynski, P; Deterministic remote two-qubit state Kaszlikowski, D; Kim, J Oh, CH Fitzsimons, JF Trappe, MI; Augenstein, P; DeKieviet, M; Nano Lett. 16, 3137 (2016) Paterek, T; Kaszlikowski, D preparation in dissipative environments Phys. Rev. A 94, 22314 (2016) Phys. Rev. A 94, 42325 (2016) Phys. Rev. A 93, 32314 (2016) Gasenzer, T; Nachtmann, O A universal test for gravitational Phys. Rev. E 93, 32407 (2016) Li, JF; Liu, JM; Feng, XL; Oh, C EPJ D 70, 76 (2016) decoherence Beating the Clauser-Horne-Shimony-Holt Quantum Inf. Process. 15, 2155 (2016) Dynamical error bounds for continuum Excessive distribution of quantum Fault-tolerant and finite-error localization Pfister, C; Kaniewski, J; Tomamichel, M; and the Svetlichny games with optimal Coherent Microwave Control of Ultracold discretisation via Gauss quadrature entanglement for point emitters within the diffraction limit Graph properties in node-query setting: Mantri, A; Schmucker, R; McMahon, N; states (NaK)-Na-23-K-40 Molecules Device-independent parallel self-testing of rules-A Lieb-Robinson bound approach Zuppardo, M; Krisnanda, T; Paterek, T; Tang, ZS; Durak, K; Ling, A effect of breaking symmetry Milburn, G; Wehner, S Su, HY; Ren, CL; Chen, JL; Zhang, FL; Will, SA; Park, JW; Yan, ZZ; Loh, HQ; two singlets Woods, MP; Plenio, MB Bandyopadhyay, S; Banerjee, A; Deb, P; Opt. Express 24, 22004 (2016) Balaji, N; Datta, S; Kulkarni, R; Podder, S Nat. Commun. 7, 13022 (2016) Wu, CF; Xu, ZP; Gu, ML; Vinjanampathy, Zwierlein, MW Wu, XY; Bancal, JD; McKague, M; J. Math. Phys. 57, 22105 (2016) Halder, S; Modi, K; Paternostro, M MFCS (2016) Scarani, V Phys. Rev. A 93, 12305 (2016) Focus on device independent quantum S; Kwek, LC Phys. Rev. Lett 116, 225306 (2016) Entangled simultaneity versus classical information Hellinger volume and number-on-the- Absolute Te-2 reference for barium ion at Phys. Rev. A 93, 22110 (2016) Phys. Rev. A 93, 62121 (2016) 455.4 nm Communication capacity of mixed interactivity in communication complexity Experimental Quantification of Asymmetric Pironio, S; Scarani, V; Vidick, T forehead communication complexity Dutta, T; De Munshi, D; Mukherjee, M Bell's Nonlocality Can be Detected by quantum t-designs Device-independent two-party Gavinsky, D Einstein-Podolsky-Rosen Steering New J. Phys. 18, 100202 (2016) Lee, T; Leonardos, N; Saks, M; Wang, FM cryptography secure against sequential Proceedings of ACM STOC (2016) Sun, K; Ye, XJ; Xu, JS; Xu, XY; Tang, JS; J. Comput. Syst. Sci. 82, 1064 (2016) J. Opt. Soc. Am. B 33, 1177 (2016) the Violation of Einstein-Podolsky-Rosen Brandsen, S; Dall'Arno, M; Szymusiak, A Fourier Analytic Approach to Quantum Steering Inequality Phys. Rev. A 94, 22335 (2016) attacks Wu, YC; Chen, JL; Li, CF; Guo, GC All the self-testings of the singlet for two Kaniewski, J; Wehner, S Entanglement convertibility by sweeping Phys. Rev. Lett 116, 160404 (2016) Estimation of Group Action Hierarchy of multipartite nonlocality in the Chen, JL; Ren, CL; Chen, CB; Ye, XJ; through the quantum phases of the Hayashi, M nonsignaling scenario binary measurements Pati, AK Conic formulations of graph New J. Phys. 18, 55004 (2016) Wang, YK; Wu, XY; Scarani, V homomorphisms alternating bonds XXZ chain Experimental test of genuine multipartite Commun. Math. Phys. 347, 3 (2016) Wang, XX; Zhang, CJ; Chen, Q; Yu, SX; Sci. Rep. 6, 39063 (2016) Dirac equation in 2-dimensional curved Tzeng, YC; Dai, L; Chung, MC; Amico, L; nonlocality under the no-signalling Yuan, HD; Oh, CH New J. Phys. 18, 25021 (2016) Roberson, DE General framework for quantum Beyond mean-field bistability in driven- Journal of Algebraic Combinatorics 43, spacetime, particle creation, and coupled Kwek, LC principle Phys. Rev. A 94, 22110 (2016) An atomtronic flux qubit: a ring lattice of waveguide arrays Sci. Rep. 6, 26453 (2016) Zhang, C; Zhang, CJ; Huang, YF; Hou, ZB; macroscopicity in terms of coherence dissipative lattices: Bunching-antibunching 877 (2016) How discord underlies the noise resilience Bose-Einstein condensates interrupted by transition and quantum simulation Koke, C; Noh, C; Angelakis, DG Liu, BH; Li, CF; Guo, GC Yadin, B; Vedral, V three weak links Converting Coherence to Quantum Ann. Phys. 374, 162 (2016) Entanglement criteria for noise resistance Sci. Rep. 6, 39327 (2016) Phys. Rev. A 93, 22122 (2016) of quantum illumination Mendoza-Arenas, JJ; Clark, SR; Felicetti, of two-qudit states Weedbrook, C; Pirandola, S; Thompson, J; Aghamalyan, D; Nguyen, NT; Auksztol, F; S; Romero, G; Solano, E; Angelakis, DG; Correlations Generation of three-photon polarization- Gan, KS; Valado, MM; Condylis, PC; Kwek, Ma, JJ; Yadin, B; Girolami, D; Vedral, V; Driven Open Quantum Systems and Dutta, A; Ryu, J; Laskowski, W; Experimental verification of multipartite Vedral, V; Gu, ML Jaksch, D Floquet Stroboscopic Dynamics Zukowski, M entanglement in quantum networks entangled decoherence-free states New J. Phys. 18, 43027 (2016) LC; Dumke, R; Amico, L Phys. Rev. A 93, 23821 (2016) Gu, M Dong, L; Lin, YF; Li, QY; Dong, HK; Xiu, New J. Phys. 18, 75013 (2016) Phys. Rev. Lett 116, 160407 (2016) Restrepo, S; Cerrillo, J; Bastidas, VM; Phys. Letter A 380, 2191 (2016) McCutcheon, W; Pappa, A; Bell, BA; Angelakis, DG; Brandes, T McMillan, A; Chailloux, A; Lawson, T; Mafu, XM; Gao, YJ How to observe duality in entanglement of Breaking RSA Generically Is Equivalent Entanglement witness via symmetric two- two distinguishable particles An exacting transition probability to Factoring Correcting for accidental correlations in Phys. Rev. Lett 117, 250401 (2016) M; Markham, D; Diamanti, E; Kerenidis, I; Ann. Phys. 371, 287 (2016) body correlations Karczewski, M; Kurzynski, P measurement - a direct test of atomic Aggarwal, D; Maurer, U saturated avalanche photodiodes Rarity, JG; Tame, MS many-body theories Grieve, JA; Chandrasekara, R; Tang, Z; Tan, EYZ; Kaszlikowski, D; Kwek, LC Nat. Commun. 7, 13251 (2016) Phys. Rev. A 94, 32124 (2016) IEEE Transactions On Information Theory Phys. Rev. A 93, 12341 (2016) Dutta, T; De Munshi, D; Yum, D; Rebhi, R; 62, 6251 (2016) Cheng, C; Ling, A Mukherjee, M Opt. Express 24, 3592 (2016) Sci. Rep. 6, 29772 (2016)

76 Centre for Quantum Technologies Annual Report 2016 77 Hubbard Model for Atomic Impurities Nanosatellite experiments to enable future Bound by the Vortex Lattice of a Rotating space-based QKD missions Bose-Einstein Condensate Bedington, R; Xueliang, B; Edward, TC; Johnson, TH; Yuan, Y; Bao, W; Clark, SR; Tan, YC; Durak, K; Zafra, AV; Grieve, J; Oi, Foot, C; Jaksch, D D; Ling, A Phys. Rev. Lett 116, 240402 (2016) EPJ Quantum Technology 3, 12 (2016) Hydrogen-plasma-induced Rapid, Low- Nearly deterministic Fredkin gate based Temperature Crystallization of mu m-thick on weak cross-Kerr nonlinearities a-Si: H Films Dong, L; Lin, YF; Wang, JX; Li, QY; Shen, Zhou, HP; Xu, M; Xu, S; Liu, LL; Liu, CX; HZ; Dong, HK; Ren, YP; Xiu, XM; Gao, YJ; Kwek, LC; Xu, LX Oh, CH Sci. Rep. 6, 32716 (2016) J. Opt. Soc. Am. B 33, 253 (2016) Implementing a neutral-atom controlled- Nearly deterministic preparation of the phase gate with a single Rydberg pulse perfect W state with weak cross-Kerr Han, R; Ng, HK; Englert, BG nonlinearities EPL 113, 40001 (2016) Dong, L; Wang, JX; Li, QY; Shen, HZ; Dong, HK; Xiu, XM; Gao, YJ; Oh, CH Improved Bounds for the Randomized Phys. Rev. A 93, 12308 (2016) Decision Tree Complexity of Recursive Majority Non-adiabatic holonomic quantum Magniez, F; Nayak, A; Santha, M; CQT researchers collaborate widely with computation in linear system-bath coupling Sherman, J; Tardos, G; Xiao, D colleagues abroad.The world map shows the Sun, CF; Wang, GC; Wu, CF; Liu, HD; Random Struct. Alg. 48, 1098 (2016) number of publications coauthored by CQTians Feng, XL; Chen, JL; Xue, K with researchers from each country. Sci. Rep. 6, 20292 (2016) Information Geometry Approach to Parameter Estimation in Markov Chains Nondestructive probing of means, Hayashi, M; Watanabe, S variances, and correlations of ultracold- Ann. Stat. 44, 1495 (2016) atomic-system densities via qubit impurities Initial system-bath state via the maximum- Elliott, TJ; Johnson, TH entropy principle Phys. Rev. A 93, 43612 (2016) Dai, JB; Len, YL; Ng, HK Phys. Rev. A 94, 52112 (2016) Nonlinear Faraday rotation on the strontium intercombination line Intensity-intensity and intensity-amplitude K. Pey, C.C. Kwong, M. Parmod, D. correlation of microwave photons from a Wilkowski. superconducting artificial atom Phys. Rev. A 93, 53428 (2016) Wang, F; Feng, XL; Oh, CH Laser Phys. Lett. 13, 105201 (2016) Nonlocal games and optimal steering at the boundary of the quantum set Leading gradient correction to the kinetic Zhen, YZ; Goh, KT; Zheng, YL; Cao, WF; energy for two-dimensional fermion gases Local quantum thermal susceptibility Measurement-device-independent Measuring correlations of cold-atom Measuring quantum correlations using More Efficient Privacy Amplification With Multipartite Quantum Correlation and Wu, XY; Chen, K; Scarani, V Trappe, MI; Len, YL; Ng, HK; Muller, CA; De Pasquale, A; Rossini, D; Fazio, R; quantification of entanglement for given systems using multiple quantum probes lossy photon-number-resolving detectors Less Random Seeds via Dual Universal Communication Complexities Phys. Rev. A 94, 22116 (2016) Englert, BG Giovannetti, V Hilbert space dimension Streif, M; Buchleitner, A; Jaksch, D; with saturation Hash Function Jain, R; Wei, ZH; Yao, P; Zhang, S Phys. Rev. A 93, 42510 (2016) Nat. Commun. 7, 12782 (2016) Goh, KT; Bancal, JD; Scarani, V Mur-Petit, J Tan, SH; Krivitsky, LA; Englert, BG Hayashi, M; Tsurumaru, T Computational Complexity 1, 30 (2016) Non-local games and optimal steering at the boundary of the quantum set Linear time algorithm for quantum {2SAT} New J. Phys. 18, 45022 (2016) Phys. Rev. A 94, 53634 (2016) J. Mod. Opt. 63, 276 (2016) IEEE Transactions On Information Theory Macroscopic limit of nonclassical 62, 2213 (2016) Y-Z Zhen, K.T. Goh, Y-L Zheng, W Cao, X. Arad, I; Santha, M; Sundaram, A; correlations MMH* with arbitrary modulus is always Wu, K. Chen, V. Scarani. Zhang, S Kurzynski, P; Kaszlikowski, D almost-universal Phys. Rev. A 94, 22116 (2016) Automata, Languages And Programming Phys. Rev. A 93, 22125 (2016) Bibak, K; Kapron, BM; Srinivasan, V (2016) Inform. Process. Lett. 116, 481 (2016)

78 Centre for Quantum Technologies Annual Report 2016 79 Observation of the S-1(0) to D-3(1) clock Partition bound is quadratically tight for Probing quantum spin glass like system Quantum quasi-Zeno dynamics: Relative thermalization Separations in communication complexity Superconducting resonator and Rydberg Three-dimensional visualization of a qutrit transition in Lu-175(+) product distributions with a double quantum dot Transitions mediated by frequent del Rio, L; Hutter, A; Renner, R; Wehner, S using cheat sheets and information atom hybrid system in the strong coupling Kurzynski, P; Kolodziejski, A; Laskowski, Arnold, KJ; Kaewuam, R; Roy, A; Paez, E; Harsha, P; Jain, R; Radhakrishnan, J Koh, CY; Kwek, LC projective measurements near the Zeno Phys. Rev. E 94, 22104 (2016) complexity regime W; Markiewicz, M Wang, S; Barrett, MD Automata, Languages And Programming J. Magn. Magn. Mater. 407, 314 (2016) regime Anshu, A; Belovs, A; Ben-David, S; Göös, Yu, D; Landra, A; Valado, MM; Hufnagel, Phys. Rev. A 93, 62126 (2016) Phys. Rev. A 94, 52512 (2016) (2016) Elliott, TJ; Vedral, V Resolved-sideband Raman cooling of an M; Jain, R; Kothari, R; Lee, T; C; Kwek, LC; Amico, L; Dumke, R Probing quantum-classical boundary with Phys. Rev. A 94, 12118 (2016) optical phonon in semiconductor materials Santha, M Phys. Rev. A 94, 062301 (2016) Time-resolved scattering of a single On deciding the existence of perfect Permutation-invariant codes encoding compression software Zhang, J; Zhang, Q; Wang, XZ; Kwek, LC; Proceedings of IEEE FOCS (2016) photon by a single atom entangled strategies for nonlocal games more than one qubit Poh, HS; Markiewicz, M; Kurzynski, P; Quantum State Transmission in a Xiong, QH Suppression of Clock Shifts at Magnetic- Leong, V; Seidler, MA; Steiner, M; Cere, A; Mancinska, L; Roberson, DE; Ouyang, Y; Fitzsimons, J Cere, A; Kaszlikowski, D; Kurtsiefer, C Superconducting Charge Qubit-Atom Nat. Photon. 10, 600 (2016) Sifting attacks in finite-size quantum key Field-Insensitive Transitions Kurtsiefer, C Varvitsiotis, A Phys. Rev. A 93, 42340 (2016) New J. Phys. 18, 35011 (2016) Hybrid distribution Arnold, KJ; Barrett, MD Nat. Commun. 7, 13716 (2016) CJTCS 1, 16 (2016) Yu, DS; Valado, MM; Hufnagel, C; Kwek, Roadmap on quantum optical systems Pfister, C; Lutkenhaus, N; Wehner, S; Phys. Rev. Lett 117, 160802 (2016) Phase locking and quantum statistics in a Probing the dynamic structure factor LC; Amico, L; Dumke, R Dumke, R; Lu, ZH; Close, J; Robins, N; Coles, PJ Two coupled one-atom lasers On the complexity of probabilistic trials for parametrically driven nonlinear resonator of a neutral Fermi superfluid along the Sci. Rep. 6, 38356 (2016) Weis, A; Mukherjee, M; Birkl, G; Hufnagel, New J. Phys. 18, 53001 (2016) Teleportation of a general two-photon Yu, DS hidden satisfiability problems Hovsepyan, GH; Shahinyan, AR; Chew, BCS-BEC crossover using atomic impurity C; Amico, L; Boshier, MG; Dieckmann, K; state employing a polarization-entangled J. Opt. Soc. Am. 33, 797 (2016) Arad, I; Boul, A; Grier, D; Santha, M; LY; Kryuchkyan, GY qubits Quantum statistics in a time-modulated Li, WH; Killian, TC Simple proof of the detectability lemma chi state with nondemolition parity Sundaram, A; Zhang, S Phys. Rev. A 93, 43856 (2016) Mitchison, MT; Johnson, TH; Jaksch, D exciton-photon system J. Opt. 18, 93001 (2016) and spectral gap amplification analyses Two photons on an atomic beam MFCS (2016) Phys. Rev. A 94, 63618 (2016) Kryuchkyan, GY; Shahinyan, AR; Anshu, A; Arad, I; Vidick, T Dong, L; Wang, JX; Li, QY; Dong, HK; Xiu, splitter: Nonlinear scattering and induced Photon-number-resolving detectors Shelykh, IA Secret Key Agreement: General Capacity Phys. Rev. B 93, 205142 (2016) XM; Gao, YJ correlations On the second-order asymptotics for and their role in quantifying quantum Protection of quantum correlations against Phys. Rev. A 93, 43857 (2016) and Second-Order Asymptotics Quantum Inf. Process. 15, 2955 (2016) Roulet, A; Le, HN; Scarani, V entanglement-assisted communication correlations decoherence Hayashi, M; Tyagi, H; Watanabe, S Single logical qubit information encoding Phys. Rev. A 93, 33838 (2016) Datta, N; Tomamichel, M; Wilde, MM Tana, SH; Krivitsky, LA; Englert, BG Sun, CF; Chen, ZH; Wang, GC; Wu, CF; Quantum thermodynamics for a model of IEEE Transactions On Information Theory scheme with the minimal optical The next iteration of the small photon Quantum Inf. Process. 15, 2569 (2016) SPIE- Quantum Communications And Xue, K; Kwek, LC an expanding Universe 62, 3796 (2016) decoherence-free subsystem entangling quantum system (SPEQS-2.0) Two-way interconversion of millimeter- Quantum Imaging XIV 9980E (2016) Quantum Inf. Process. 15, 773 (2016) Liu, NN; Goold, J; Fuentes, I; Vedral, V; Dong, L; Wang, JX; Li, QY; Shen, HZ; Durak, K; Villar, A; Septriani, B; Tang, ZK; wave and optical fields in Rydberg gases Optical bistability and multistability via Modi, K; Bruschi, DE Secure Multiplex Coding With Dependent Dong, HK; Xiu, XM; Gao, YJ Chandrasekara, R; Bedington, R; Ling, A Kiffner, M; Feizpour, A; Kaczmarek, KT; quantum coherence in chiral molecules Pinning of fermionic occupation numbers: QMA with subset state witnesses Class. Quantum Grav. 33, 35003 (2016) and Non-Uniform Multiple Messages Opt. Lett. 41, 1030 (2016) Proceedings of SPIE- Advances in Jaksch, D; Nunn, J Wang, F; Feng, XL; Oh, CH General concepts and one spatial Grilo, AB; Kerenidis, I; Sikora, J Hayashi, M; Matsumoto, R Photonics of Quantum Computing, New J. Phys. 18, 93030 (2016) Opt. Express 24, 13702 (2016) dimension MFCS (2016) Rabi oscillation in a quantum cavity: IEEE Transactions On Information Theory Solving the scattering of N photons on a Memory, and Communication IX 9762, Corrigendum: Two-way interconversion Tennie, F; Ebler, D; Vedral, V; Schilling, C Markovian and non-Markovian dynamics 62, 2355 (2016) two-level atom without computation 976209 (2016) Optical intensity interferometry through Phys. Rev. A 93, 42126 (2016) Quantum conditional operations Guimond, PO; Roulet, A; Le, HN; Roulet, A; Scarani, V of millimeter-wave and optical fields in atmospheric turbulence Bisio, A; Dall'Arno, M; Perinotti, P Scarani, V Security Analysis of epsilon-Almost Dual New J. Phys. 18, 93035 (2016) The photon pair source that survived a Rydberg gases (vol 18, 093030, 2016) Tan, PK; Chan, AH; Kurtsiefer, C Pinning of fermionic occupation numbers: Phys. Rev. A 94, 22340 (2016) Phys. Rev. A 93, 23808 (2016) Universal(2) Hash Functions: Smoothing rocket explosion Kiffner, M; Feizpour, A; Kaczmarek, KT; Mon. Not. R. Astron. Soc. 457, 4291 (2016) Higher spatial dimensions and spin of Min Entropy Versus Smoothing of Renyi Spectral shift and dephasing of Tang, ZK; Chandrasekara, R; Tan, YC; Jaksch, D; Nunn, J Tennie, F; Vedral, V; Schilling, C Quantum mechanical calculation of Random numbers from vacuum Entropy of Order 2 electromagnetically induced transparency New J. Phys. 18, 109502 (2016) Optimal bounds for parity-oblivious random Rydberg-Rydberg Auger decay rates Cheng, C; Durak, K; Ling, A Phys. Rev. A 94, 12120 (2016) fluctuations Hayashi, M in an interacting Rydberg gas Sci. Rep. 6, 25603 (2016) access codes Kiffner, M; Ceresoli, D; Li, W; Jaksch, D Shi, YC; Chng, B; Kurtsiefer, C IEEE Transactions On Information Theory Han, JS; Vogt, T; Li, WH Uniform Random Number Generation Chailloux, A; Kerenidis, I; Kundu, S; Possible light-induced superconductivity in J. Phys. B 49, 204004 (2016) Appl. Phys. Lett 109, 41101 (2016) 62, 3451 (2016) Phys. Rev. A 94, 43806 (2016) The Space "Just Above" BQP From Markov Chains: Non-Asymptotic and Sikora, J K3C60 at high temperature Aaronson, S; Bouland, A; Fitzsimons, J; Asymptotic Analyses New J. 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80 Centre for Quantum Technologies Annual Report 2016 81 EVENTS

Conferences & Workshops

14-18 3 4-8 18-20 NOV OCT July Jan

Quantum Engineering Quantum-Safe Crypto International Workshop SU(N), gauge Science and Workshop 2016, Conference on Quantum fields and cold atoms, Technologies Singapore Communication, Singapore Symposium (QuESTS) Measurement and 2016, Singapore Level 3 Seminar Room, CQT, Computing (QCMC) Level 3 Seminar Room, CQT, Singapore Singapore 2016, Singapore University Town Plaza, Auditorium 1 NUS, Singapore University Town Stephen Riady Centre, NUS, Singapore

82 Centre for Quantum Technologies Annual Report 2016 83 OUTREACH Sharing science and people news throughout the year

A year in events March June July August September October November December In March, CQT was the creative We were at Singapore’s Maker CQT Principal Investigator We exhibited and offered a Quantum Shorts launched as a film The launch of the NUS-Singtel Principal Investigator Manas Our most talked-about research partner for the NUS Arts Festival Faire in June – attended by crowds Alexander Ling spoke at the talk on CQT’s work with small festival with an open call for films Cyber Security Research and Mukherjee appeared in the TV show paper of the year was “Time- 2016: Wonder, presented by NUS of more than 15,000 – offering EuroScience Open Forum, the satellites, known as cubesats, at up to five minutes long inspired Development Laboratory (see pp. Make me a Super on Singapore resolved scattering of a single Centre for the Arts (see pp. 60–61 virtual reality visits to CQT research largest interdisciplinary science the inaugural one north festival in by quantum physics. The festival 66–67) hit the news in October. The channel okto. The science series photon by a single atom” published for details). labs and an interactive ‘laser meeting in Europe. It was held in Singapore in August. The festival is supported by media partners Straits Times, ZDNet and Channel aimed at kids explored research as Nature Communications 7, spirograph sound visualiser’ built the UK in July. He featured in the drew 6000 visitors. The exhibit Scientific American and Nature, NewsAsia were among those to run in Singapore through the lens of 13715 (2016) on 2 December, with by CQT students. panel session "Quantum theory was in partnership with the NUS scientific partners and screening stories. In all, there were more than superpowers. Manas showed how more than 17 media mentions. in space: more than just rocket Faculty of Engineering and startup partners. It will end with screenings 40 articles on CQT or CQT research he cools atoms to near absolute Over 200 participants in the NUS science". Bhattacharya Space Enterprises. in 2017. in 2016. zero. Physics Enrichment camp visited CQT for lab tours this month. We Alexander Ling, the Principal also hosted some 30 students for Investigator leading work on CQT’s a week for Generation Q Camp quantum cubesat, was widely (pictured). quoted in the media after China launched its own quantum satellite. He was also interviewed for live TV show The Rundown on CNBC.

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86 Centre for Quantum Technologies Annual Report 2016 87 NRF CRP The John Templeton Foundation Four grants from Singapore's National Research Foundation (NRF) under Two grants support the projects "Occam's Quantum Mechanical its Competitive Research Programme support projects "Hybrid Quantum Razor" (USD 246,100 ) led by Mile Gu and "Many Box Locality as a Technologies" ($4,325,456) led by Christian Kurtsiefer, "Space Based Physical Principal" ($147,200) led by Valerio Scarani. Quantum Key Distribution" ($5,869,535) led by Alexander Ling, "QSYNC: Theory and experiments of quantum synchronisation in trapped ions and nano-mechanical resonators" ($4,555,766) led by Vlatko Vedral and "Engineering of a Scalable Photonics Platform for Quantum Enabled Technologies" ($323,760) led out of A*STAR's Data Storage Institute MONEY MATTERS with CQT's Kwek Leong Chuan as co-PI. MOE Tier 2 & 3 MERLION CQT has four research projects supported in 2016 by competitive A two-year MERLION workshop grant ($30,000) from the Institut funding from Singapore's Ministry of Education (MOE). The largest is Francais supports the organisation of a Quantum Engineering Expenditure in 2016 "Random numbers from Quantum Processes" ($9,931,731) involving 13 Science and Technologies Symposium (QuESTS), bringing together PIs led by Valerio Scarani. The other projects are "Dynamics of coherent researchers from France and Singapore. The project is led by Kwek Manpower Other Equipment TOTAL dipole-dipole energy transport of Rydberg excitations" ($782,610) Leong Chuan. Core 4,741,536 2,879,762 669,104 8,290,402 led by Wenhui Li, "Controlling Quantum Matter: Dipolar Molecules in Optical Lattices" ($770,139) led by Kai Dieckmann and "Atomtronics- persistent currents through ring lattice architectures" ($859,248) led by Rainer Dumke. External 1,158,523 761,445 378,744 2,298,712 NRF CRP A*STAR Singapore's Agency for Science, Technology and Rearch (A*STAR) Stakeholder support MOE Tier 2 & 3 1,086,048 730,137 103,277 1,919,462 funds a 3-year project ($664,143) led by Murray Barrett on the development of an optical atomic clock based on small ensembles of A*STAR 74,732 36,109 15,237 126,078 CQT's operations are supported by its stakeholders through singly ionized Lutetium. direct funding and other contributions. Singapore's National NRF Fellowship - 103,503 2,990 106,493 Research Foundation and Ministry of Education (MOE) awarded $195 million in core funding for the Centre's first ten years. Following the Centre's international review in 2015, CQT will The John Templeton Foundation 71,887 19,370 - 91,257 receive a further $100 million in follow-on-funding starting in 2017. MERLION - 27,724 - 27,724 CQT is an autonomous research centre hosted by the National NRF Fellowship University of Singapore, with additional staff and facilities at the Total 7,132,726 4,558,050 1,169,352 12,860,128 Computer scientist Troy Lee is funded by a five-year Fellowship Nanyang Technological University (NTU). Support from the ($2,710,660) from Singapore's National Research Foundation. universities includes provision of building space, administrative Portions of the grant are managed by the Nanyang Technological staff and contributions to PI salaries commensurate with the PI's For a listing of all current grants, see University. service to the university. www.quantumlah.org/main/funding

88 Centre for Quantum Technologies Annual Report 2016 89 SUPPORTERS

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