DOCSLIB.ORG

Dephasing Enhanced Transport in Boundary-Driven Quasiperiodic Chains

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text
Dephasing Enhanced Transport in Boundary-Driven Quasiperiodic Chains Dephasing enhanced transport in boundary-driven quasiperiodic chains Artur M. Lacerda,1, 2 John Goold,2 and Gabriel T. Landi1 1Instituto de Física, Universidade de São Paulo, CEP 05314-970, São Paulo, São Paulo, Brazil 2Department of Physics, Trinity College Dublin, Dublin 2, Ireland We study dephasing-enhanced transport in boundary-driven quasi-periodic systems. Specifically we consider dephasing modelled by current preserving Lindblad dissipators acting on the non-interacting Aubry-André- Harper (AAH) and Fibonacci bulk systems. The former is known to undergo a critical localization transition with a suppression of ballistic transport above a critical value of the potential. At the critical point, the presence of non-ergodic extended states yields anomalous sub-diffusion. The Fibonacci model, on the other hand, yields anomalous transport with a continuously varying exponent depending on the potential strength. By computing the covariance matrix in the non-equilibrium steady-state, we show that sufficiently strong dephasing always renders the transport diffusive. The interplay between dephasing and quasi-periodicity gives rise to a maximum of the diffusion coefficient for finite dephasing, which suggests the combination of quasi-periodic geometries and dephasing can be used to control noise-enhanced transport. I. INTRODUCTION to explore the many-body localised phase [37]. In the AAH, at fixed tunneling rate and below a critical value of the po- tential strength, all the energy eigenstates are delocalized, Non-equilibrium systems are characterized by the existence while above this value the entire spectrum is localized. This of macroscopic currents of energy or matter [1]. Understand- transition is clearly reflected in the non-equilibrium trans- ing these transport properties has, for more than a century, port properties, with particle transport going from ballistic to been a major field of research in physics. One of the fun- exponentially suppressed. At criticality, the eigenstates are damental issues is to ascertain the necessary ingredients in a neither delocalized nor localized, and the transport is sub- model to induce a certain transport regime. Low dimensional diffusive [30, 38]. Generalizations of the AAH model ex- systems, in particular, have received significant attention both hibiting mobility-edges have also been analyzed in the trans- in the classical [2,3] and quantum regimes [4]. For instance, port scenario [39]. A closely related model is the Fibonacci chains of harmonic oscillators present ballistic transport [5], model [40–43]. This model has a critical spectrum which which is fundamentally different from the diffusive behavior has been studied in detail [40, 42–44]. This unique spec- obtained in Fourier’s law of heat conduction [6]. However, trum gives rise to highly anomalous transport in the absence not all anharmonicities lead to diffusivity [7,8]. In addition of interactions where the transport exponent varies continu- to being fundamental, being able to understand and control ously with the potential strength. In fact, the transport in transport offers opportunities for potential device applications. the Fibonacci model can be tuned continuously, from ballistic Transport in low-dimensional devices, for instance, can be to sub-diffusive. While the quantum transport properties of manipulated for steady state thermal machines [9] and nano- quasi-periodic systems is well studied, recently studies have scale heat engineering [10–13]. highlighted that they can be exploited for thermal engineer- For low dimensional quantum many-body systems, the ing [45, 46]. technique of boundary-driving has been used widely to ex- In this work we are interested in how the anomalous trans- tract high temperature transport properties in non-equilibrium port, typically observed in quasi-periodic systems, is affected steady-states (NESSs) [14–22]. Boundary-driving is an open by dephasing noise from an environment. One phenomeno- systems technique where local Lindblad dissipators at the logical approach to model dephasing is by means means of edges of the chain induce a gradient in spin and or energy. self-consistent baths [47], also known as Büttiker probes [48]. Transport coefficients can then be extracted from finite size Another approach, which we will exploit here, is via current- scaling of the currents [4, 23]. Although the technique is lim- preserving Lindblad dissipators. For any non-zero dephas- ited to high temperature physics it has a distinct advantage in arXiv:2106.11406v1 [quant-ph] 21 Jun 2021 ing strengths, free tight-binding models typically become dif- so much as it can be extended to models with integrability fusive in the thermodynamic limit [16, 49]. Motivated by breaking perturbations [24, 25] by means of tensor networks. these results, we study the effects of dephasing in quasiperi- This technique has been instrumental in shedding light on the odic systems. We numerically compute the covariance ma- transport properties of the ergodic phase of interacting dis- trix in the NESS and study the finite size scaling of the par- ordered models [26–29] and systems with magnetic impuri- ticle current. Both the AAH model and the Fibonacci model ties [24, 25]. become diffuive in the presence of dephasing noise. Interest- Another class of models where boundary driving has been ingly, though, in certain regimes this introduces a competition, applied successfully is quasi-periodic chains [30–32]. A where the dephasing leads to noise-enhanced transport. The paradigmatic example is the Aubry-André-Harper (AAH) paper is divided as follows. The model is described in Sec.II model [33, 34], which is known to undergo a localization tran- and the analysis of the transport properties of both models, sition when the potential strength is increased. The model with and without dephasing, are discussed in Sec. III. Our is readily simulated in ultra-cold atomic physics experiments, main results are presented in Sec.IV, where we analyze the using bichromatic optical lattices [35, 36], and has been used interplay between quasi-periodicity and dephasing. Conclu- 2 sions are summarized in Sec.V. where γ is the coupling strength, fi is the Fermi-Dirac distri- bution of the bath and D is a Lindblad operator of the form 1n o II. THE MODEL D[L] = LρLy − LyL; ρ : (7) 2 A. Boundary-driven XX chain deph Similarly, Di in Eq. (5) describes the dephasing on site i, and is given by Consider a one-dimensional spin 1/2 (or free Fermion) sys- deph y tem with L sites, described by the XX (tight-binding) Hamil- Di (ρ) = ΓD[ci ci] (8) tonian where Γ is the dephasing strength. L−1 L X + − − + λ X z If the sites were uncoupled, a bath of the form (6) would H = − σ σ + σ σ + Viσ (1) i i+1 i i+1 2 i lead to the equilibrium state ρeq = f j0ih0j+(1− f ) j1ih1j, where i=1 i z D y E hσ i = 2 f − 1 and c c = f . Hence, the difference ∆ f = fL − L−1 L X X f1 can be interpreted as either a magnetization or a population − y y y = ci ci+1 + ci+1ci + λ Vici ci; (2) imbalance in the chain. As long as ∆ f , 0, the system will i=1 i converge to non-equilibrium steady state (NESS) with a non- zero magnetization (particle) current, given by which are equivalent via a Jordan-Wigner transformation ci = Qi−1 z − j=1(−σi )σi . We consider two models, defined by two D y y E Ji = i c ci − c ci+1 : (9) different choices of the onsite potential Vi, with strength λ i+1 i (Fig.1(a)). The first is the Aubry-André-Harper (AAH) For the internal sites, i = 2;:::; L − 1, these currents satisfy a model, in which the on-site potential is given by [33, 34] continuity equation V = 2 cos(2πgi + θ); (3) i d D y E p ci ci = Ji−1 − Ji; i = 2;:::; L − 1; (10) where g = (1 + 5)=2 is the golden ratio. This model un- dt dergoes a localization transition at λc = 1. When λ < 1, all which is obtained directly from Eq. (5). The sites at energy eigenstates are delocalized, and when λ > 1 they are the boundaries are subject to additional currents J0 = all localized. Similar results also follow when g is any other y y tr c1c1D1(ρ) and JL = tr cLcLDL(ρ) . Crucially, note that Diophantine number [50]. The second system is the Fibonacci the dephasing dissipators do not affect the continuity equa- model, with a potential is defined by [40–43] tion (10). There is, therefore, no particle exchange with them. D E " # " # In the NESS, d cyc =dt = 0. Hence, by Eq. (10) the cur- i + 1 i i i V = − ; (4) rent becomes homogeneous throughout the chain: i g2 g2 J = J = ··· = J ≡ J: (11) where [x] is the integer part of x. This represents the ith ele- 1 2 L−1 ment of a binary sequence called Fibonacci word, which can We can thus unambiguously refer to the particle current sim- be constructed by the recursive rule S n = S n−2 + S n−1, with ply as J. In the spin chain formulation, the particle current S 0 = 0, S 1 = 01 and “+” taken as concatenation. Successive naturally translates to a magnetization current, application of this rule generates the words: D E J = 2i σxσy − σyσx : (12) 0 ! 01 ! 010 ! 01001 ! 01001010 !··· i i i+1 i i+1 This definition can also be obtained by writing an explicit ex- Notice that each Fibonacci word is an extension of the previ- D E pression for d σz =dt and interpreting it as a continuity equa- ous one; Vi is then the ith digit of any word with size greater or i equal to i. Additionally, the length of each word is a Fibonacci tion, similarly to Eq.
Load more

Recommended publications
  • Physical Review Journals Catalog 2021
    2021 PHYSICAL REVIEW JOURNALS CATALOG PUBLISHED BY THE AMERICAN PHYSICAL SOCIETY Physical Review Journals 2021 1 © 2020 American Physical Society 2 Physical Review Journals 2021 Table of Contents Founded in 1899, the American Physical Society (APS) strives to advance and diffuse the knowledge of physics. In support of this objective, APS publishes primary research and review journals, five of which are open access. Physical Review Letters..............................................................................................................2 Physical Review X .......................................................................................................................3 PRX Quantum .............................................................................................................................4 Reviews of Modern Physics ......................................................................................................5 Physical Review A .......................................................................................................................6 Physical Review B ......................................................................................................................7 Physical Review C.......................................................................................................................8 Physical Review D ......................................................................................................................9 Physical Review E ...................................................................................................................
    [Show full text]
  • Citation Statistics from 110 Years of Physical Review
    Citation Statistics from 110 Years of Physical Review Publicly available data reveal long-term systematic features about citation statistics and how papers are referenced. The data also tell fascinating citation histories of individual articles. Sidney Redner he first article published in the Physical Review was Treceived in 1893; the journal’s first volume included 6 issues and 24 articles. In the 20th century, the Phys- ical Review branched into topical sections and spawned new journals (see figure 1). Today, all arti- cles in the Physical Review family of journals (PR) are available online and, as a useful byproduct, all cita- tions in PR articles are electronically available. The citation data provide a treasure trove of quantitative information. As individuals who write sci- entific papers, most of us are keenly interested in how often our own work is cited. As dispassionate observers, we Figure 1. The Physical Review can use the citation data to identify influential research, was the first member of a family new trends in research, unanticipated connections across of journals that now includes two series of Physical fields, and downturns in subfields that are exhausted. A Review, the topical journals Physical Review A–E, certain pleasure can also be gleaned from the data when Physical Review Letters (PRL), Reviews of Modern Physics, they reveal the idiosyncratic features in the citation his- and Physical Review Special Topics: Accelerators and tories of individual articles. Beams. The first issue of Physical Review bears a publica- The investigation of citation statistics has a long his- tion date a year later than the receipt of its first article.
    [Show full text]
  • Dephasing Time of Gaas Electron-Spin Qubits Coupled to a Nuclear Bath Exceeding 200 Μs
    LETTERS PUBLISHED ONLINE: 12 DECEMBER 2010 | DOI: 10.1038/NPHYS1856 Dephasing time of GaAs electron-spin qubits coupled to a nuclear bath exceeding 200 µs Hendrik Bluhm1(, Sandra Foletti1(, Izhar Neder1, Mark Rudner1, Diana Mahalu2, Vladimir Umansky2 and Amir Yacoby1* Qubits, the quantum mechanical bits required for quantum the Overhauser field to the electron-spin precession before and computing, must retain their quantum states for times after the spin reversal then approximately cancel out. For longer long enough to allow the information contained in them to evolution times, the effective field acting on the electron spin be processed. In many types of electron-spin qubits, the generally changes over the precession interval. This change leads primary source of information loss is decoherence due to to an eventual loss of coherence on a timescale determined by the the interaction with nuclear spins of the host lattice. For details of the nuclear spin dynamics. electrons in gate-defined GaAs quantum dots, spin-echo Previous Hahn-echo experiments on lateral GaAs quantum dots measurements have revealed coherence times of about 1 µs have demonstrated spin-dephasing times of around 1 µs at relatively at magnetic fields below 100 mT (refs 1,2). Here, we show low magnetic fields up to 100 mT for microwave-controlled2 single- that coherence in such devices can survive much longer, and electron spins and electrically controlled1 two-electron-spin qubits. provide a detailed understanding of the measured nuclear- For optically controlled self-assembled quantum dots, coherence spin-induced decoherence. At fields above a few hundred times of 3 µs at 6 T were found5.
    [Show full text]
  • Writing Physics Papers
    Physics 2151W Lab Manual | Page 45 WID Handbook for Intermediate Laboratory - Physics 2151W Writing Physics Papers Dr. Igor Strakovsky Department of Physics, GWU Publish or Perish - Presentation of Scientific Results Intermediate Laboratory – Physics 2151W is focused on significantly improving the students' writing skills with respect to producing scientific papers, to do peer reviews, and presentations at the Physics Department Mini-Workshop. Third Edition, 2013 Physics 2151W Lab Manual | Page 46 OUTLINE Why are we Writing Papers? What Physics Journals are there? Structure of a Physics Article. Style of Technical Papers. Hints for Effective Writing. Submit and Fight. Why are We Writing Papers? To communicate our original, interesting, and useful research. To let others know what we are working on (and that we are working at all.) To organize our thoughts. To formulate our research in a comprehensible way. To secure further funding. To further our careers. To make our publication lists look more impressive. To make our Citation Index very impressive. To have fun? Because we believe someone is going to read it!!! Physics 2151W Lab Manual | Page 47 What Physics Journals are there? Hard Science Journals Physical Review Series: Physical Review A Physical Review E http://pra.aps.org/ http://pre.aps.org/ Atomic, Molecular, and Optical physics. Stat, Non-Linear, & Soft Material Phys. Physical Review B Physical Review Letters http://prb.aps.org/ http://prl.aps.org/ Condensed matter and Materials physics. Moving physics forward. Physical Review C Review of Modern Physics http://prc.aps.org/ http://rmp.aps.org/ Nuclear physics. Reviews in all areas. Physical Review D http://prd.aps.org/ Particles, Fields, Gravitation, and Cosmology.
    [Show full text]
  • Effect of Exchange Interaction on Spin Dephasing in a Double Quantum Dot
    PHYSICAL REVIEW LETTERS week ending PRL 97, 056801 (2006) 4 AUGUST 2006 Effect of Exchange Interaction on Spin Dephasing in a Double Quantum Dot E. A. Laird,1 J. R. Petta,1 A. C. Johnson,1 C. M. Marcus,1 A. Yacoby,2 M. P. Hanson,3 and A. C. Gossard3 1Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA 2Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot 76100, Israel 3Materials Department, University of California at Santa Barbara, Santa Barbara, California 93106, USA (Received 3 December 2005; published 31 July 2006) We measure singlet-triplet dephasing in a two-electron double quantum dot in the presence of an exchange interaction which can be electrically tuned from much smaller to much larger than the hyperfine energy. Saturation of dephasing and damped oscillations of the spin correlator as a function of time are observed when the two interaction strengths are comparable. Both features of the data are compared with predictions from a quasistatic model of the hyperfine field. DOI: 10.1103/PhysRevLett.97.056801 PACS numbers: 73.21.La, 71.70.Gm, 71.70.Jp Implementing quantum information processing in solid- Enuc. When J Enuc, we find that PS decays on a time @ state circuitry is an enticing experimental goal, offering the scale T2 =Enuc 14 ns. In the opposite limit where possibility of tunable device parameters and straightfor- exchange dominates, J Enuc, we find that singlet corre- ward scaling. However, realization will require control lations are substantially preserved over hundreds of nano- over the strong environmental decoherence typical of seconds.
    [Show full text]
  • Decoherence and Dephasing in a Quantum Measurement Process
    PHYSICAL REVIEW A VOLUME 54, NUMBER 2 AUGUST 1996 Decoherence and dephasing in a quantum measurement process Naoyuki Kono, 1 Ken Machida, 1 Mikio Namiki, 1 and Saverio Pascazio 2 1Department of Physics, Waseda University, Tokyo 169, Japan 2Dipartimento di Fisica, Universita` di Bari, and Istituto Nazionale di Fisica Nucleare, Sezione di Bari, I-70126 Bari, Italy ~Received 19 April 1995; revised manuscript received 22 January 1996! We numerically simulate the quantum measurement process by modeling the measuring apparatus as a one-dimensional Dirac comb that interacts with an incoming object particle. The global effect of the apparatus can be well schematized in terms of the total transmission probability and the decoherence parameter, which quantitatively characterizes the loss of quantum-mechanical coherence and the wave-function collapse by measurement. These two quantities alone enable one to judge whether the apparatus works well or not as a detection system. We derive simple theoretical formulas that are in excellent agreement with the numerical results, and can be very useful in order to make a ‘‘design theory’’ of a measuring system ~detector!. We also discuss some important characteristics of the wave-function collapse. @S1050-2947~96!07507-5# PACS number~s!: 03.65.Bz I. INTRODUCTION giving a quantitative estimate of the dephasing occurring in a quantum measurement process. A similar philosophy has Quantum mechanics is the most fundamental physical been followed by several authors at different times. Among theory developed during the last seventy years. Nevertheless, others, quantitative measures for decoherence were also pro- physicists still debate the quantum measurement problem posed by Caldeira and Leggett @6# and Paz, Habib, and Zurek @1,2#, which has caused them to ponder over some very fun- @7#.
    [Show full text]
  • NMR for Condensed Matter Physics
    Concise History of NMR 1926 ‐ Pauli’s prediction of nuclear spin Gorter 1932 ‐ Detection of nuclear magnetic moment by Stern using Stern molecular beam (1943 Nobel Prize) 1936 ‐ First theoretical prediction of NMR by Gorter; attempt to detect the first NMR failed (LiF & K[Al(SO4)2]12H2O) 20K. 1938 ‐ Prof. Rabi, First detection of nuclear spin (1944 Nobel) 2015 Maglab Summer School 1942 ‐ Prof. Gorter, first published use of “NMR” ( 1967, Fritz Rabi Bloch London Prize) Nuclear Magnetic Resonance 1945 ‐ First NMR, Bloch H2O , Purcell paraffin (shared 1952 Nobel Prize) in Condensed Matter 1949 ‐ W. Knight, discovery of Knight Shift 1950 ‐ Prof. Hahn, discovery of spin echo. Purcell 1961 ‐ First commercial NMR spectrometer Varian A‐60 Arneil P. Reyes Ernst 1964 ‐ FT NMR by Ernst and Anderson (1992 Nobel Prize) NHMFL 1972 ‐ Lauterbur MRI Experiment (2003 Nobel Prize) 1980 ‐ Wuthrich 3D structure of proteins (2002 Nobel Prize) 1995 ‐ NMR at 25T (NHMFL) Lauterbur 2000 ‐ NMR at NHMFL 45T Hybrid (2 GHz NMR) Wuthrichd 2005 ‐ Pulsed field NMR >60T Concise History of NMR ‐ Old vs. New Modern Developments of NMR Magnets Technical improvements parallel developments in electronics cryogenics, superconducting magnets, digital computers. Advances in NMR Magnets 70 100T Superconducting 60 Resistive Hybrid 50 Pulse 40 Nb3Sn 30 NbTi 20 MgB2, HighTc nanotubes 10 0 1950 1960 1970 1980 1990 2000 2010 2020 2030 NMR in medical and industrial applications ¬ MRI, functional MRI ¬ non‐destructive testing ¬ dynamic information ‐ motion of molecules ¬ petroleum ‐ earth's field NMR , pore size distribution in rocks Condensed Matter ChemBio ¬ liquid chromatography, flow probes ¬ process control – petrochemical, mining, polymer production.
    [Show full text]
  • Arxiv:1511.04819V2 [Physics.Atom-Ph] 23 Feb 2016 fluctuations Emanating from the Metallic Surfaces [7–9]
    Implications of surface noise for the motional coherence of trapped ions I. Talukdar1, D. J. Gorman1, N. Daniilidis1, P. Schindler1, S. Ebadi1;3, H. Kaufmann1;4, T. Zhang1;5, H. H¨affner1;2∗ 1Department of Physics, University of California, Berkeley, 94720, Berkeley, CA 2Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720 3University of Toronto, Canada 4University of Mainz, Germany and 5Peking University, China (Dated: February 24, 2016) Electric noise from metallic surfaces is a major obstacle towards quantum applications with trapped ions due to motional heating of the ions. Here, we discuss how the same noise source can also lead to pure dephasing of motional quantum states. The mechanism is particularly relevant at small ion-surface distances, thus imposing a new constraint on trap miniaturization. By means of a free induction decay experiment, we measure the dephasing time of the motion of a single ion trapped 50 µm above a Cu-Al surface. From the dephasing times we extract the integrated noise below the secular frequency of the ion. We find that none of the most commonly discussed surface noise models for ion traps describes both, the observed heating as well as the measured dephasing, satisfactorily. Thus, our measurements provide a benchmark for future models for the electric noise emitted by metallic surfaces. PACS numbers: 37.10.Ty, 73.50.Td, 05.40.Ca, 03.65.Yz Understanding decoherence constitutes an integral ning probe microscopy [17], gravitational wave experi- part in the development of any quantum technology. All ments [18], superconducting electronics [2], detection of present implementations of a quantum bit have to con- Casimir forces [19], and studies of non-contact friction tend with the deleterious effects of decoherence [1{5].
    [Show full text]
  • Style and Notation Guide
    Physical Review Style and Notation Guide Instructions for correct notation and style in preparation of REVTEX compuscripts and conventional manuscripts Published by The American Physical Society First Edition July 1983 Revised February 1993 Compiled and edited by Minor Revision June 2005 Anne Waldron, Peggy Judd, and Valerie Miller Minor Revision June 2011 Copyright 1993, by The American Physical Society Permission is granted to quote from this journal with the customary acknowledgment of the source. To reprint a figure, table or other excerpt requires, in addition, the consent of one of the original authors and notification of APS. No copying fee is required when copies of articles are made for educational or research purposes by individuals or libraries (including those at government and industrial institutions). Republication or reproduction for sale of articles or abstracts in this journal is permitted only under license from APS; in addition, APS may require that permission also be obtained from one of the authors. Address inquiries to the APS Administrative Editor (Editorial Office, 1 Research Rd., Box 1000, Ridge, NY 11961). Physical Review Style and Notation Guide Anne Waldron, Peggy Judd, and Valerie Miller (Received: ) Contents I. INTRODUCTION 2 II. STYLE INSTRUCTIONS FOR PARTS OF A MANUSCRIPT 2 A. Title ..................................................... 2 B. Author(s) name(s) . 2 C. Author(s) affiliation(s) . 2 D. Receipt date . 2 E. Abstract . 2 F. Physics and Astronomy Classification Scheme (PACS) indexing codes . 2 G. Main body of the paper|sequential organization . 2 1. Types of headings and section-head numbers . 3 2. Reference, figure, and table numbering . 3 3.
    [Show full text]
  • Electron Dephasing in Metal and Semiconductor Mesoscopic Structures
    INSTITUTE OF PHYSICS PUBLISHING JOURNAL OF PHYSICS: CONDENSED MATTER J. Phys.: Condens. Matter 14 (2002) R501–R596 PII: S0953-8984(02)16903-7 TOPICAL REVIEW Recent experimental studies of electron dephasing in metal and semiconductor mesoscopic structures J J Lin1,3 and J P Bird2,3 1 Institute of Physics, National Chiao Tung University, Hsinchu 300, Taiwan 2 Department of Electrical Engineering, Arizona State University, Tempe, AZ 85287, USA E-mail: [email protected] and [email protected] Received 13 February 2002 Published 26 April 2002 Online at stacks.iop.org/JPhysCM/14/R501 Abstract In this review, we discuss the results of recent experimental studies of the low-temperature electron dephasing time (τφ) in metal and semiconductor mesoscopic structures. A major focus of this review is on the use of weak localization, and other quantum-interference-related phenomena, to determine the value of τφ in systems of different dimensionality and with different levels of disorder. Significant attention is devoted to a discussion of three-dimensional metal films, in which dephasing is found to predominantly arise from the influence of electron–phonon (e–ph) scattering. Both the temperature and electron mean free path dependences of τφ that result from this scattering mechanism are found to be sensitive to the microscopic quality and degree of disorder in the sample. The results of these studies are compared with the predictions of recent theories for the e–ph interaction. We conclude that, in spite of progress in the theory for this scattering mechanism, our understanding of the e–ph interaction remains incomplete.
    [Show full text]
  • Optical Characterization of Ferromagnetic and Multiferroic Thin- Film Heterostructures
    W&M ScholarWorks Dissertations, Theses, and Masters Projects Theses, Dissertations, & Master Projects 2015 Optical characterization of ferromagnetic and multiferroic thin- film heterostructures Xin Ma College of William & Mary - Arts & Sciences Follow this and additional works at: https://scholarworks.wm.edu/etd Part of the Artificial Intelligence and Robotics Commons Recommended Citation Ma, Xin, "Optical characterization of ferromagnetic and multiferroic thin-film heterostructures" (2015). Dissertations, Theses, and Masters Projects. Paper 1539623372. https://dx.doi.org/doi:10.21220/s2-66yg-6612 This Dissertation is brought to you for free and open access by the Theses, Dissertations, & Master Projects at W&M ScholarWorks. It has been accepted for inclusion in Dissertations, Theses, and Masters Projects by an authorized administrator of W&M ScholarWorks. For more information, please contact [email protected]. Optical Characterization of Ferromagnetic and Multiferroic Thin-Film Heterostructures Xin Ma Lingbi, Suzhou, Anhui, P. R. China Bachelor of Science, the University of Science and Technology of China, 2009 A Dissertation presented to the Graduate Faculty of the College of William and Mary in Candidacy for the Degree of Doctor of Philosophy Department of Applied Science The College of William and Mary January, 2015 APPROVAL PAGE This Dissertation is submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy 10 I ' I o- Xin Ma Approved by the Committee, November, 2014 Committee Cnair Professor Gunter Luepke, Applied Science The College of William and Mary Professor Michael Kelley, Applied Science The College of William and Mary Professor Mark Hinders, Applied Science The College of William and Mary Professor Mumtaz Qazilbash, Physics The College of William and Mary ABSTRACT This thesis presents optical characterization of the static and dynamic magnetic interactions in ferromagnetic and multiferroic heterostructures with time-resolved and interface-specific optical techniques.
    [Show full text]
  • Superconducting Qubits: Dephasing and Quantum Chemistry
    UNIVERSITY of CALIFORNIA Santa Barbara Superconducting Qubits: Dephasing and Quantum Chemistry A dissertation submitted in partial satisfaction of the requirements for the degree of Doctor of Philosophy in Physics by Peter James Joyce O'Malley Committee in charge: Professor John Martinis, Chair Professor David Weld Professor Chetan Nayak June 2016 The dissertation of Peter James Joyce O'Malley is approved: Professor David Weld Professor Chetan Nayak Professor John Martinis, Chair June 2016 Copyright c 2016 by Peter James Joyce O'Malley v vi Any work that aims to further human knowledge is inherently dedicated to future generations. There is one particular member of the next generation to which I dedicate this particular work. vii viii Acknowledgements It is a truth universally acknowledged that a dissertation is not the work of a single person. Without John Martinis, of course, this work would not exist in any form. I will be eter- nally indebted to him for ideas, guidance, resources, and|perhaps most importantly| assembling a truly great group of people to surround myself with. To these people I must extend my gratitude, insufficient though it may be; thank you for helping me as I ventured away from superconducting qubits and welcoming me back as I returned. While the nature of a university research group is to always be in flux, this group is lucky enough to have the possibility to continue to work together to build something great, and perhaps an order of magnitude luckier that we should wish to remain so. It has been an honor. Also indispensable on this journey have been all the members of the physics depart- ment who have provided the support I needed (and PCS, I apologize for repeatedly ending up, somehow, on your naughty list).
    [Show full text]