DOCSLIB.ORG

Chapter 10 Dynamic Condensation of Exciton-Polaritons

Total Page：16

File Type：pdf, Size：1020Kb

Download full-text PDF Read full-text

Load more

Chapter 10 Dynamic condensation of exciton-polaritons 1 REVIEWS OF MODERN PHYSICS, VOLUME 82, APRIL–JUNE 2010 Exciton-polariton Bose-Einstein condensation Hui Deng Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA Hartmut Haug Institut für Theoretische Physik, Goethe Universität Frankfurt, Max-von-Laue-Street 1, D-60438 Frankfurt am Main, Germany Yoshihisa Yamamoto Edward L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA; National Institute of Informatics, Hitotsubashi, Chiyoda-ku, Tokyo 101-8430, Japan; and NTT Basic Research Laboratories, NTT Corporation, Atsugi, Kanagawa 243-0198, Japan ͑Published 12 May 2010͒ In the past decade, a two-dimensional matter-light system called the microcavity exciton-polariton has emerged as a new promising candidate of Bose-Einstein condensation ͑BEC͒ in solids. Many pieces of important evidence of polariton BEC have been established recently in GaAs and CdTe microcavities at the liquid helium temperature, opening a door to rich many-body physics inaccessible in experiments before. Technological progress also made polariton BEC at room temperatures promising. In parallel with experimental progresses, theoretical frameworks and numerical simulations are developed, and our understanding of the system has greatly advanced. In this article, recent experiments and corresponding theoretical pictures based on the Gross-Pitaevskii equations and the Boltzmann kinetic simulations for a finite-size BEC of polaritons are reviewed. DOI: 10.1103/RevModPhys.82.1489 PACS number͑s͒: 71.35.Lk, 71.36.ϩc, 42.50.Ϫp, 78.67.Ϫn CONTENTS A. Polariton-phonon scattering 1500 B. Polariton-polariton scattering 1500 1. Nonlinear polariton interaction coefficients 1500 I. Introduction 1490 2. Polariton-polariton scattering rates 1502 II. Semiconductor Microcavity Polaritons 1491 C. Semiclassical Boltzmann rate equations 1502 A. Wannier-Mott exciton 1491 IV. Stimulated Scattering, Amplification, and Lasing of 1. Exciton optical transition 1492 Exciton Polaritons 1503 2. Quantum-well exciton 1492 A. Observation of bosonic final-state stimulation 1503 B. Semiconductor microcavity 1492 B. Polariton amplifier 1504 C. Quantum-well microcavity polariton 1493 C. Polariton lasing versus photon lasing 1505 1. The Hamiltonian 1493 1. Experiment 1505 2. Polariton dispersion and effective mass 1494 2. Numerical simulation with quasistationary 3. Polariton decay 1494 and pulsed pumping 1507 4. Very strong-coupling regime 1495 V. Thermodynamics of Polariton Condensation 1508 D. Polaritons for quantum phase research 1495 A. Time-integrated momentum distribution 1508 1. Critical densities of 2D quasi-BEC and B. Time constants of the dynamical processes 1508 BKT phase transitions 1495 C. Detuning and thermalization 1509 2. Quantum phases at high excitation densities 1496 D. Time-resolved momentum distribution 1509 3. Experimental advantages of polaritons for E. Numerical simulations 1510 BEC study 1496 F. Steady-state momentum distribution 1511 E. Experimental methodology 1497 VI. Angular Momentum and Polarization Kinetics 1511 1. Typical material systems 1497 A. Formulation of the quasispin kinetics 1512 2. Structure design considerations 1498 B. Time-averaged and time-resolved experiments and 3. In situ tuning parameters 1498 simulations 1513 4. Measurement techniques 1498 C. Stokes vector measurement 1515 F. Theoretical methods 1498 VII. Coherence Properties 1515 1. Semiclassical Boltzmann kinetics 1498 A. The second-order coherence function 1516 2. Quantum kinetics 1499 1. g͑2͒͑0͒ of the LP ground state 1516 3. Equilibrium and steady-state properties 1499 2. Kinetic models of the g͑2͒ 1517 4. System size 1499 3. Master equation with gain saturation 1518 III. Rate Equations of Polariton Kinetics 1499 4. Stationary solution 1519 0034-6861/2010/82͑2͒/1489͑49͒ 1489 ©2010 The American Physical Society 1490 Deng, Haug, and Yamamoto: Exciton-polariton Bose-Einstein condensation 5. Numerical solutions of the master equation 1519 ting into an upper and lower branches of polaritons 1 6. Nonresonant two-polariton scattering ͑Weisbuch et al., 1992͒. ͑quantum depletion͒ 1520 The metastable state of lower polaritons at zero in- B. First-order temporal coherence 1521 plane momentum ͑kʈ =0͒ has recently emerged as a new C. First-order spatial coherence 1521 candidate for observing Bose-Einstein condensation 2 1. Long-range spatial coherence in a ͑BEC͒ in solids ͑Imamoglu et al., 1996͒. The experimen- condensate 1521 tal advantage of polariton BEC over conventional exci- ͑ ͒ 2. Spatial coherence among bottleneck LPs 1521 ton BEC Hanamura and Haug, 1977 is twofold. Near 3. Spatial coherence between fragments of a kʈ =0, a polariton has an effective mass of four orders of condensate 1522 magnitude lighter than a bare exciton mass, so the criti- 4. Spatial coherence of a single-spatial mode cal temperature for reaching polariton BEC is four or- ders of magnitude higher than that for reaching exciton condensate 1522 BEC at the same particle density or equivalently the 5. Theory and simulations 1522 critical density for reaching polariton BEC is four orders D. Spatial distributions 1523 of magnitude lower than that for reaching exciton BEC 1. Condensate size and critical density 1523 at the same temperature. The second advantage of this 2. Comparison to a photon laser 1523 system is that a polariton can easily extend a phase- VIII. Polariton Superfluidity 1524 coherent wave function in space through its photonic A. Gross-Pitaevskii equation 1524 component in spite of unavoidable crystal defects and B. Bogoliubov excitation spectrum 1525 disorders, while a bare exciton is easily localized in a C. Blueshift of the condensate mean-field energy 1525 fluctuating potential inside a crystal, which is a notorious D. Energy vs momentum dispersion relation 1526 enemy to the exciton BEC. E. Universal features of Bogoliubov excitations 1527 Polaritons have a very short lifetime due to fast pho- F. Thermal and quantum depletion 1528 ton leakage rate from a microcavity. In most cases, po- G. Quantized vortices 1528 laritons have a lifetime shorter than the cooling time to IX. Polariton Condensation in Single Traps and Periodic the metastable ground state, so that the system remains Lattice Potentials 1528 in a nonequilibrium condition without a well-defined A. Polariton traps 1529 temperature or chemical potential. However, when the 1. Optical traps by metal masks 1529 cavity-photon resonance is detuned to higher than that ͑ ͒ 2. Optical traps by fabrication 1529 of the QW exciton blue detuning , the lower polariton ͑ ͒ 3. Exciton traps by mechanical stress 1529 LP has an increased excitonic component, a longer life- B. Polariton array in lattice potential 1529 time, and a shorter cooling time, facilitating thermaliza- 1. One-dimensional periodic array of tion. In the limit of a very large blue detuning, the dy- namical polariton laser becomes indistinguishable from polaritons 1530 the thermal-equilibrium exciton BEC. In a recent ex- 2. Band structure, metastable ␲ state, and periment, a quantum degenerate polariton gas was ob- stable zero-state 1531 served with a chemical potential ␮ well within the BEC 3. Dynamics and mode competition 1532 regime, −␮/k TϽ0.1, and at a polariton gas tempera- X. Outlook 1532 B ture T very close to the lattice ͑phonon reservoir͒ tem- Acknowledgments 1534 perature of ϳ4K͑Deng et al., 2006͒. The excitonic com- Appendix: Calculation of Scattering Coefficients 1534 ponent of polaritons in this experiment is up to 80%. References 1535 However, the system is still metastable and the quantum degenerate gas exists only for several tens of picosec- onds. The dynamical nature of a polariton condensate I. INTRODUCTION places a limitation for studying the standard BEC phys- ics, but it also provides a new experimental tool for The experimental technique of controlling spontane- studying a nonequilibrium open system consisting of ous emission of an atom by a cavity is referred to as highly degenerate interacting bosons. This is not an eas- cavity quantum electrodynamics. It has been studied for ily accessible problem by atomic BEC or superfluid 4He a variety of atomic systems ͑Berman, 1994͒. In solids, systems. One unique feature of a polariton system, com- the inhibited and enhanced spontaneous emission was pared to dilute atomic BEC and dense superfluid 4He, is observed for two-dimensional ͑2D͒ quantum well ͑QW͒ excitons in semiconductor planar microcavities ͑Yama- 1 moto et al., 1989; Björk et al., 1991͒. Due to a very strong Since we discuss exclusively exciton polaritons in semicon- collective dipole interaction between QW excitons and ductors, we abbreviate exciton-polariton as polariton in this paper. microcavity photon fields, even with a relatively low-Q 2 The metastable state of upper polaritons at kʈ =0 in principle cavity, the planar microcavity system features a revers- may also undergo BEC. But the fast scattering from the upper ible spontaneous emission and thus normal-mode split- to the lower branch makes such a condensation unlikely. Rev. Mod. Phys., Vol. 82, No. 2, April–June 2010 Deng, Haug, and Yamamoto: Exciton-polariton Bose-Einstein condensation 1491 the direct experimental accessibility to the quantum- single isolated trap and one-dimensional array of traps statistical properties of the condensate. The main decay are presented in Sec. IX. A minimum uncertainty wave channel of polaritons is the photon leakage from a cavity packet close to the Heisenberg limit and competition in which
Recommended publications
  • UNIVERSITY of CALIFORNIA, SAN DIEGO Exciton Transport

    UNIVERSITY of CALIFORNIA, SAN DIEGO Exciton Transport

    UNIVERSITY OF CALIFORNIA, SAN DIEGO Exciton Transport Phenomena in GaAs Coupled Quantum Wells A dissertation submitted in partial satisfaction of the requirements for the degree Doctor of Philosophy in Physics by Jason R. Leonard Committee in charge: Professor Leonid V. Butov, Chair Professor John M. Goodkind Professor Shayan Mookherjea Professor Charles W. Tu Professor Congjun Wu 2016 Copyright Jason R. Leonard, 2016 All rights reserved. The dissertation of Jason R. Leonard is approved, and it is acceptable in quality and form for publication on microfilm and electronically: Chair University of California, San Diego 2016 iii TABLE OF CONTENTS Signature Page . iii Table of Contents . iv List of Figures . vi Acknowledgements . viii Vita........................................ x Abstract of the Dissertation . xii Chapter 1 Introduction . 1 1.1 Semiconductor introduction . 2 1.1.1 Bulk GaAs . 3 1.1.2 Single Quantum Well . 3 1.1.3 Coupled-Quantum Wells . 5 1.2 Transport Physics . 7 1.3 Spin Physics . 8 1.3.1 D'yakanov and Perel' spin relaxation . 10 1.3.2 Dresselhaus Interaction . 10 1.3.3 Electron-Hole Exchange Interaction . 11 1.4 Dissertation Overview . 11 Chapter 2 Controlled exciton transport via a ramp . 13 2.1 Introduction . 13 2.2 Experimental Methods . 14 2.3 Qualitative Results . 14 2.4 Quantitative Results . 16 2.5 Theoretical Model . 17 2.6 Summary . 19 2.7 Acknowledgments . 19 Chapter 3 Controlled exciton transport via an optically controlled exciton transistor . 22 3.1 Introduction . 22 3.2 Realization . 22 3.3 Experimental Methods . 23 3.4 Results . 25 3.5 Theoretical Model .
  • Arxiv:2104.14459V2 [Cond-Mat.Mes-Hall] 13 Aug 2021 Rymksnnaeinayn Uha Bspromising Prop- Mbss This As Such Subsequent Anyons Commuting

    Arxiv:2104.14459V2 [Cond-Mat.Mes-Hall] 13 Aug 2021 Rymksnnaeinayn Uha Bspromising Prop- Mbss This As Such Subsequent Anyons Commuting

    Majorana bound states in semiconducting nanostructures Katharina Laubscher1 and Jelena Klinovaja1 Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland (Dated: 16 August 2021) In this Tutorial, we give a pedagogical introduction to Majorana bound states (MBSs) arising in semiconduct- ing nanostructures. We start by briefly reviewing the well-known Kitaev chain toy model in order to introduce some of the basic properties of MBSs before proceeding to describe more experimentally relevant platforms. Here, our focus lies on simple ‘minimal’ models where the Majorana wave functions can be obtained explicitly by standard methods. In a first part, we review the paradigmatic model of a Rashba nanowire with strong spin-orbit interaction (SOI) placed in a magnetic field and proximitized by a conventional s-wave supercon- ductor. We identify the topological phase transition separating the trivial phase from the topological phase and demonstrate how the explicit Majorana wave functions can be obtained in the limit of strong SOI. In a second part, we discuss MBSs engineered from proximitized edge states of two-dimensional (2D) topological insulators. We introduce the Jackiw-Rebbi mechanism leading to the emergence of bound states at mass domain walls and show how this mechanism can be exploited to construct MBSs. Due to their recent interest, we also include a discussion of Majorana corner states in 2D second-order topological superconductors. This Tutorial is mainly aimed at graduate students—both theorists and experimentalists—seeking to familiarize themselves with some of the basic concepts in the field. I. INTRODUCTION In 1937, the Italian physicist Ettore Majorana pro- posed the existence of an exotic type of fermion—later termed a Majorana fermion—which is its own antiparti- cle.1 While the original idea of a Majorana fermion was brought forward in the context of high-energy physics,2 it later turned out that emergent excitations with re- FIG.
  • The New Era of Polariton Condensates David W

    The New Era of Polariton Condensates David W

    The new era of polariton condensates David W. Snoke, and Jonathan Keeling Citation: Physics Today 70, 10, 54 (2017); doi: 10.1063/PT.3.3729 View online: https://doi.org/10.1063/PT.3.3729 View Table of Contents: http://physicstoday.scitation.org/toc/pto/70/10 Published by the American Institute of Physics Articles you may be interested in Ultraperipheral nuclear collisions Physics Today 70, 40 (2017); 10.1063/PT.3.3727 Death and succession among Finland’s nuclear waste experts Physics Today 70, 48 (2017); 10.1063/PT.3.3728 Taking the measure of water’s whirl Physics Today 70, 20 (2017); 10.1063/PT.3.3716 Microscopy without lenses Physics Today 70, 50 (2017); 10.1063/PT.3.3693 The relentless pursuit of hypersonic flight Physics Today 70, 30 (2017); 10.1063/PT.3.3762 Difficult decisions Physics Today 70, 8 (2017); 10.1063/PT.3.3706 David Snoke is a professor of physics and astronomy at the University of Pittsburgh in Pennsylvania. Jonathan Keeling is a reader in theoretical condensed-matter physics at the University of St Andrews in Scotland. The new era of POLARITON CONDENSATES David W. Snoke and Jonathan Keeling Quasiparticles of light and matter may be our best hope for harnessing the strange effects of quantum condensation and superfluidity in everyday applications. magine, if you will, a collection of many photons. Now and applied—remains to turn those ideas into practical technologies. But the dream imagine that they have mass, repulsive interactions, and isn’t as distant as it once seemed. number conservation.
  • Chapter 09584

    Chapter 09584

    Author's personal copy Excitons in Magnetic Fields Kankan Cong, G Timothy Noe II, and Junichiro Kono, Rice University, Houston, TX, United States r 2018 Elsevier Ltd. All rights reserved. Introduction When a photon of energy greater than the band gap is absorbed by a semiconductor, a negatively charged electron is excited from the valence band into the conduction band, leaving behind a positively charged hole. The electron can be attracted to the hole via the Coulomb interaction, lowering the energy of the electron-hole (e-h) pair by a characteristic binding energy, Eb. The bound e-h pair is referred to as an exciton, and it is analogous to the hydrogen atom, but with a larger Bohr radius and a smaller binding energy, ranging from 1 to 100 meV, due to the small reduced mass of the exciton and screening of the Coulomb interaction by the dielectric environment. Like the hydrogen atom, there exists a series of excitonic bound states, which modify the near-band-edge optical response of semiconductors, especially when the binding energy is greater than the thermal energy and any relevant scattering rates. When the e-h pair has an energy greater than the binding energy, the electron and hole are no longer bound to one another (ionized), although they are still correlated. The nature of the optical transitions for both excitons and unbound e-h pairs depends on the dimensionality of the e-h system. Furthermore, an exciton is a composite boson having integer spin that obeys Bose-Einstein statistics rather than fermions that obey Fermi-Dirac statistics as in the case of either the electrons or holes by themselves.
  • Majorana Fermions in Quantum Wires and the Influence of Environment

    Majorana Fermions in Quantum Wires and the Influence of Environment

    Freie Universitat¨ Berlin Department of Physics Master thesis Majorana fermions in quantum wires and the influence of environment Supervisor: Written by: Prof. Karsten Flensberg Konrad W¨olms Prof. Piet Brouwer 25. May 2012 Contents page 1 Introduction 5 2 Majorana Fermions 7 2.1 Kitaev model . .9 2.2 Helical Liquids . 12 2.3 Spatially varying Zeeman fields . 14 2.3.1 Scattering matrix criterion . 16 2.4 Application of the criterion . 17 3 Majorana qubits 21 3.1 Structure of the Majorana Qubits . 21 3.2 General Dephasing . 22 3.3 Majorana 4-point functions . 24 3.4 Topological protection . 27 4 Perturbative corrections 29 4.1 Local perturbations . 29 4.1.1 Calculation of the correlation function . 30 4.1.2 Non-adiabatic effects of noise . 32 4.1.3 Uniform movement of the Majorana fermion . 34 4.2 Coupling between Majorana fermions . 36 4.2.1 Static perturbation . 36 4.3 Phonon mediated coupling . 39 4.3.1 Split Majorana Green function . 39 4.3.2 Phonon Coupling . 40 4.3.3 Self-Energy . 41 4.3.4 Self Energy in terms of local functions . 43 4.4 Calculation of B ................................ 44 4.4.1 General form for the electron Green function . 46 4.5 Calculation of Σ . 46 5 Summary 51 6 Acknowledgments 53 Bibliography 55 3 1 Introduction One of the fascinating aspects of condensed matter is the emergence of quasi-particles. These often describe the low energy behavior of complicated many-body systems extremely well and have long become an essential tool for the theoretical description of many condensed matter system.
  • Amplitude/Higgs Modes in Condensed Matter Physics

    Amplitude/Higgs Modes in Condensed Matter Physics

    Amplitude / Higgs Modes in Condensed Matter Physics David Pekker1 and C. M. Varma2 1Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, PA 15217 and 2Department of Physics and Astronomy, University of California, Riverside, CA 92521 (Dated: February 10, 2015) Abstract The order parameter and its variations in space and time in many different states in condensed matter physics at low temperatures are described by the complex function Ψ(r; t). These states include superfluids, superconductors, and a subclass of antiferromagnets and charge-density waves. The collective fluctuations in the ordered state may then be categorized as oscillations of phase and amplitude of Ψ(r; t). The phase oscillations are the Goldstone modes of the broken continuous symmetry. The amplitude modes, even at long wavelengths, are well defined and decoupled from the phase oscillations only near particle-hole symmetry, where the equations of motion have an effective Lorentz symmetry as in particle physics, and if there are no significant avenues for decay into other excitations. They bear close correspondence with the so-called Higgs modes in particle physics, whose prediction and discovery is very important for the standard model of particle physics. In this review, we discuss the theory and the possible observation of the amplitude or Higgs modes in condensed matter physics – in superconductors, cold-atoms in periodic lattices, and in uniaxial antiferromagnets. We discuss the necessity for at least approximate particle-hole symmetry as well as the special conditions required to couple to such modes because, being scalars, they do not couple linearly to the usual condensed matter probes.
  • Exciton Binding Energy in Small Organic Conjugated Molecule

    Exciton Binding Energy in Small Organic Conjugated Molecule

    1 Exciton Binding Energy in small organic conjugated molecule. Pabitra K. Nayak* Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot, 76100, Israel Email: [email protected] Abstract: For small organic conjugated molecules the exciton binding energy can be calculated treating molecules as conductor, and is given by a simple relation BE ≈ 2 e /(4πε0εR), where ε is the dielectric constant and R is the equivalent radius of the molecule. However, if the molecule deviates from spherical shape, a minor correction factor should be added. 1. Introduction An understanding of the energy levels in organic semiconductors is important for designing electronic devices and for understanding their function and performance. The absolute hole transport level and electron transport level can be obtained from theoretical calculations and also from photoemission experiments [1][2][3]. The difference between the two transport levels is referred to as the transport gap (Et). The transport gap is different from the optical gap (Eopt) in organic semiconductors. This is because optical excitation gives rise to excitons rather than free carriers. These excitons are Frenkel excitons and localized to the molecule, hence an extra amount of energy, termed as exciton binding energy (Eb) is needed to produce free charge carriers. What is the magnitude of Eb in organic semiconductors? Answer to this question is more relevant in emerging field of Organic Photovoltaic cells (OPV), due to their impact in determining the output voltage of the solar cells. A lot of efforts are also going on to develop new absorbing material for OPV. It is also important to guess the magnitude of exciton binding energy before the actual synthesis of materials.
  • Pion-Induced Transport of Π Mesons in Nuclei

    Pion-Induced Transport of Π Mesons in Nuclei

    Central Washington University ScholarWorks@CWU All Faculty Scholarship for the College of the Sciences College of the Sciences 2-8-2000 Pion-induced transport of π mesons in nuclei S. G. Mashnik R. J. Peterson A. J. Sierk Michael R. Braunstein Follow this and additional works at: https://digitalcommons.cwu.edu/cotsfac Part of the Atomic, Molecular and Optical Physics Commons, and the Nuclear Commons PHYSICAL REVIEW C, VOLUME 61, 034601 Pion-induced transport of ␲ mesons in nuclei S. G. Mashnik,1,* R. J. Peterson,2 A. J. Sierk,1 and M. R. Braunstein3 1T-2, Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 2Nuclear Physics Laboratory, University of Colorado, Boulder, Colorado 80309 3Physics Department, Central Washington University, Ellensburg, Washington 98926 ͑Received 28 May 1999; published 8 February 2000͒ A large body of data for pion-induced neutral pion continuum spectra spanning outgoing energies near 180 MeV shows no dip there that might be ascribed to internal strong absorption processes involving the formation of ⌬’s. This is the same observation previously made for the charged pion continuum spectra. Calculations in an intranuclear cascade model or a cascade exciton model with free-space parameters predict such a dip for both neutral and charged pions. We explore several medium modifications to the interactions of pions with internal nucleons that are able to reproduce the data for nuclei from 7Li through Bi. PACS number͑s͒: 25.80.Hp, 25.80.Gn, 25.80.Ls, 21.60.Ka I. INTRODUCTION the NCX data at angles forward of 90° by a factor of 2 ͓3͔.
  • Phonon-Exciton Interactions in Wse2 Under a Quantizing Magnetic Field

    Phonon-Exciton Interactions in Wse2 Under a Quantizing Magnetic Field

    ARTICLE https://doi.org/10.1038/s41467-020-16934-x OPEN Phonon-exciton Interactions in WSe2 under a quantizing magnetic field Zhipeng Li1,10, Tianmeng Wang 1,10, Shengnan Miao1,10, Yunmei Li2,10, Zhenguang Lu3,4, Chenhao Jin 5, Zhen Lian1, Yuze Meng1, Mark Blei6, Takashi Taniguchi7, Kenji Watanabe 7, Sefaattin Tongay6, Wang Yao 8, ✉ Dmitry Smirnov 3, Chuanwei Zhang2 & Su-Fei Shi 1,9 Strong many-body interaction in two-dimensional transitional metal dichalcogenides provides 1234567890():,; a unique platform to study the interplay between different quasiparticles, such as prominent phonon replica emission and modified valley-selection rules. A large out-of-plane magnetic field is expected to modify the exciton-phonon interactions by quantizing excitons into dis- crete Landau levels, which is largely unexplored. Here, we observe the Landau levels origi- nating from phonon-exciton complexes and directly probe exciton-phonon interaction under a quantizing magnetic field. Phonon-exciton interaction lifts the inter-Landau-level transition selection rules for dark trions, manifested by a distinctively different Landau fan pattern compared to bright trions. This allows us to experimentally extract the effective mass of both holes and electrons. The onset of Landau quantization coincides with a significant increase of the valley-Zeeman shift, suggesting strong many-body effects on the phonon-exciton inter- action. Our work demonstrates monolayer WSe2 as an intriguing playground to study phonon-exciton interactions and their interplay with charge, spin, and valley. 1 Department of Chemical and Biological Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. 2 Department of Physics, The University of Texas at Dallas, Richardson, TX 75080, USA.
  • Tunable Phonon Polaritons in Atomically Thin Van Der Waals Crystals of Boron Nitride

    Tunable Phonon Polaritons in Atomically Thin Van Der Waals Crystals of Boron Nitride

    Tunable Phonon Polaritons in Atomically Thin van der Waals Crystals of Boron Nitride The MIT Faculty has made this article openly available. Please share how this access benefits you. Your story matters. Citation Dai, S., Z. Fei, Q. Ma, A. S. Rodin, M. Wagner, A. S. McLeod, M. K. Liu, et al. “Tunable Phonon Polaritons in Atomically Thin van Der Waals Crystals of Boron Nitride.” Science 343, no. 6175 (March 7, 2014): 1125–1129. As Published http://dx.doi.org/10.1126/science.1246833 Publisher American Association for the Advancement of Science (AAAS) Version Author's final manuscript Citable link http://hdl.handle.net/1721.1/90317 Terms of Use Creative Commons Attribution-Noncommercial-Share Alike Detailed Terms http://creativecommons.org/licenses/by-nc-sa/4.0/ Tunable phonon polaritons in atomically thin van der Waals crystals of boron nitride Authors: S. Dai1, Z. Fei1, Q. Ma2, A. S. Rodin3, M. Wagner1, A. S. McLeod1, M. K. Liu1, W. Gannett4,5, W. Regan4,5, K. Watanabe6, T. Taniguchi6, M. Thiemens7, G. Dominguez8, A. H. Castro Neto3,9, A. Zettl4,5, F. Keilmann10, P. Jarillo-Herrero2, M. M. Fogler1, D. N. Basov1* Affiliations: 1Department of Physics, University of California, San Diego, La Jolla, California 92093, USA 2Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA 3Department of Physics, Boston University, Boston, Massachusetts 02215, USA 4Department of Physics and Astronomy, University of California, Berkeley, Berkeley, California 94720, USA 5Materials Sciences Division, Lawrence Berkeley
  • Introducing Coherent Time Control to Cavity Magnon-Polariton Modes

    Introducing Coherent Time Control to Cavity Magnon-Polariton Modes

    ARTICLE https://doi.org/10.1038/s42005-019-0266-x OPEN Introducing coherent time control to cavity magnon-polariton modes Tim Wolz 1*, Alexander Stehli1, Andre Schneider 1, Isabella Boventer1,2, Rair Macêdo 3, Alexey V. Ustinov1,4, Mathias Kläui 2 & Martin Weides 1,3* 1234567890():,; By connecting light to magnetism, cavity magnon-polaritons (CMPs) can link quantum computation to spintronics. Consequently, CMP-based information processing devices have emerged over the last years, but have almost exclusively been investigated with single-tone spectroscopy. However, universal computing applications will require a dynamic and on- demand control of the CMP within nanoseconds. Here, we perform fast manipulations of the different CMP modes with independent but coherent pulses to the cavity and magnon sys- tem. We change the state of the CMP from the energy exchanging beat mode to its normal modes and further demonstrate two fundamental examples of coherent manipulation. We first evidence dynamic control over the appearance of magnon-Rabi oscillations, i.e., energy exchange, and second, energy extraction by applying an anti-phase drive to the magnon. Our results show a promising approach to control building blocks valuable for a quantum internet and pave the way for future magnon-based quantum computing research. 1 Institute of Physics, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany. 2 Institute of Physics, Johannes Gutenberg University Mainz, 55099 Mainz, Germany. 3 James Watt School of Engineering, Electronics & Nanoscale Engineering
  • Amplitude Modes in Cold Atoms

    Amplitude Modes in Cold Atoms

    T01 Amplitude modes in cold atoms S.D. Huber, Institute for Theoretical Physics, ETH Zurich E-mail address: [email protected] The Bose Hubbard model exhibits a quantum phase transition between an insulating Mott state and a superfluid. We aim at the determination of the excitation spectrum of the superfluid phase, in particular its evolution from the vicinity of the Mott phase towards the weakly interacting regime. Furthermore, we discuss a method allowing to observe our findings in an experiment. We make the link between our microscopic findings and the notion of a “Higgs” mode. Specifically, we highlight the role of emergent symmetries. Recent developments in the description of amplitude modes in exotic chiral Mott insulators will be mentioned. [1] S.D. Huber, E. Altman, H.P. Buchler,¨ and G. Blatter, Phys. Rev. B, 75 085106 (2007) [2] S.D. Huber, B. Theiler, E. Altman, G. Blatter, Phys. Rev. Lett., 100 050404 (2008) [3] S.D. Huber and N.H. Lindner, Proc. Natl. Acad. Sci. USA, 108 19925 (2011) T02 Higgs mode and universal dynamics near quantum criticality D. Podolsky Department of Physics, Technion – Israel Institute of Technology, Haifa 32000, Israel E-mail address: [email protected] The Higgs mode is a ubiquitous collective excitation in condensed matter systems with broken continuous symmetry. Its detection is a valuable test of the corresponding field theory, and its mass gap measures the proximity to a quantum critical point. However, since the Higgs mode can decay into low energy Goldstone modes, its experimental visibility has been questioned. In this talk, I will show that the visibility of the Higgs mode depends on the symmetry of the measured susceptibility.