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Fletcher RJ, Zwierlein M. Photons think inside the box. Science 2022; 375:1355-1356. [PMID: 35324311 DOI: 10.1126/science.abo2856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Light confined to a sheet offers a glimpse into low-dimensional quantum gases.
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Affiliation(s)
- Richard J Fletcher
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Martin Zwierlein
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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2
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Sun Z, Beaumariage J, Wan Q, Alnatah H, Hougland N, Chisholm J, Cao Q, Watanabe K, Taniguchi T, Hunt BM, Bondarev IV, Snoke D. Charged Bosons Made of Fermions in Bilayer Structures with Strong Metallic Screening. NANO LETTERS 2021; 21:7669-7675. [PMID: 34516139 DOI: 10.1021/acs.nanolett.1c02422] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Two-dimensional monolayer structures of transition metal dichalogenides (TMDs) have been shown to allow many higher-order excitonic bound states, including trions (charged excitons), biexcitons (excitonic molecules), and charged biexcitons. We report here experimental evidence and the theoretical basis for a new bound excitonic complex, consisting two free carriers bound to an exciton in a bilayer structure. Our experimental measurements on structures made using two different materials show a new spectral line at the predicted energy with two different TMD materials (MoSe2 and WSe2) with both n- and p-doping if and only if all the required theoretical conditions for this complex are fulfilled, in particular, only in the presence of a parallel metal layer that significantly screens the repulsive interaction between the like-charge carriers. Because these four-carrier bound states are charged bosons, they could eventually be the basis for a new path to superconductivity without Cooper pairing.
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Affiliation(s)
- Zheng Sun
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200241, China
| | - Jonathan Beaumariage
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Qiaochu Wan
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Hassan Alnatah
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Nicholas Hougland
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Jessica Chisholm
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
| | - Qingrui Cao
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Kenji Watanabe
- National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
| | - Takashi Taniguchi
- National Institute for Materials Science, Tsukuba, Ibaraki 305-0044, Japan
| | - Benjamin Matthew Hunt
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, United States
| | - Igor V Bondarev
- Department of Mathematics and Physics, North Carolina Central University, Durham, North Carolina 27707, United States
| | - David Snoke
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, United States
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3
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Weill R, Bekker A, Levit B, Fischer B. Bose-Einstein condensation of photons in a long fiber cavity. OPTICS EXPRESS 2021; 29:27807-27815. [PMID: 34615189 DOI: 10.1364/oe.430406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/05/2021] [Accepted: 07/26/2021] [Indexed: 06/13/2023]
Abstract
We demonstrate photon Bose-Einstein condensation (photon-BEC) at a broad temperature range that is valid also in the long 1D fiber cavity limit. It is done with an erbium-ytterbium co-doped fiber (EYDF) cavity by overcoming the challenging requirement of sublinear light dispersion for BEC in 1D using a chirped-gratings Fabry-Perot. We experimentally show with a square-root mode-dispersion, a quadratic temperature dependence of the critical power for condensation (compared to a linear dependence in finite regular fiber-cavities) between 90 K and 382 K, as the theory predicts.
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4
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Öztürk FE, Lappe T, Hellmann G, Schmitt J, Klaers J, Vewinger F, Kroha J, Weitz M. Observation of a non-Hermitian phase transition in an optical quantum gas. Science 2021; 372:88-91. [PMID: 33795457 DOI: 10.1126/science.abe9869] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2020] [Accepted: 02/23/2021] [Indexed: 12/24/2022]
Abstract
Quantum gases of light, such as photon or polariton condensates in optical microcavities, are collective quantum systems enabling a tailoring of dissipation from, for example, cavity loss. This characteristic makes them a tool to study dissipative phases, an emerging subject in quantum many-body physics. We experimentally demonstrate a non-Hermitian phase transition of a photon Bose-Einstein condensate to a dissipative phase characterized by a biexponential decay of the condensate's second-order coherence. The phase transition occurs because of the emergence of an exceptional point in the quantum gas. Although Bose-Einstein condensation is usually connected to lasing by a smooth crossover, the observed phase transition separates the biexponential phase from both lasing and an intermediate, oscillatory condensate regime. Our approach can be used to study a wide class of dissipative quantum phases in topological or lattice systems.
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Affiliation(s)
- Fahri Emre Öztürk
- Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115 Bonn, Germany
| | - Tim Lappe
- Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn, Germany
| | - Göran Hellmann
- Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115 Bonn, Germany
| | - Julian Schmitt
- Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115 Bonn, Germany.
| | - Jan Klaers
- Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115 Bonn, Germany
| | - Frank Vewinger
- Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115 Bonn, Germany
| | - Johann Kroha
- Physikalisches Institut, Universität Bonn, Nussallee 12, 53115 Bonn, Germany
| | - Martin Weitz
- Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, 53115 Bonn, Germany.
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5
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Dos Santos MCP, Malomed BA, Cardoso WB. Double-layer Bose-Einstein condensates: A quantum phase transition in the transverse direction, and reduction to two dimensions. Phys Rev E 2020; 102:042209. [PMID: 33212641 DOI: 10.1103/physreve.102.042209] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Accepted: 09/22/2020] [Indexed: 06/11/2023]
Abstract
We revisit the problem of the reduction of the three-dimensional (3D) dynamics of Bose-Einstein condensates, under the action of strong confinement in one direction (z), to a 2D mean-field equation. We address this problem for the confining potential with a singular term, viz., V_{z}(z)=2z^{2}+ζ^{2}/z^{2}, with constant ζ. A quantum phase transition is induced by the latter term, between the ground state (GS) of the harmonic oscillator and the 3D condensate split in two parallel noninteracting layers, which is a manifestation of the "superselection" effect. A realization of the respective physical setting is proposed, making use of resonant coupling to an optical field, with the resonance detuning modulated along z. The reduction of the full 3D Gross-Pitaevskii equation (GPE) to the 2D nonpolynomial Schrödinger equation (NPSE) is based on the factorized ansatz, with the z -dependent multiplier represented by an exact GS solution of the 1D Schrödinger equation with potential V_{z}(z). For both repulsive and attractive signs of the nonlinearity, the 2D NPSE produces GS and vortex states, that are virtually indistinguishable from the respective numerical solutions provided by full 3D GPE. In the case of the self-attraction, the threshold for the onset of the collapse, predicted by the 2D NPSE, is also virtually identical to its counterpart obtained from the 3D equation. In the same case, stability and instability of vortices with topological charge S=1, 2, and 3 are considered in detail. Thus, the procedure of the spatial-dimension reduction, 3D → 2D, produces very accurate results, and it may be used in other settings.
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Affiliation(s)
- Mateus C P Dos Santos
- Instituto de Física, Universidade Federal de Goiás 74.690-970, Goiânia, Goiás, Brazil
| | - Boris A Malomed
- Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, and Center for Light-Matter Interaction, Tel Aviv University, Tel Aviv 69978, Israel
- Instituto de Alta Investigación, Universidad de Tarapacá, Casilla 7D, Arica, Chile
| | - Wesley B Cardoso
- Instituto de Física, Universidade Federal de Goiás 74.690-970, Goiânia, Goiás, Brazil
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6
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Bekker A, Levit B, Weill R, Fischer B. Nonlinear light mode dispersion and nonuniform mode comb by a Fabry-Perot with chirped fiber gratings. OPTICS EXPRESS 2020; 28:18135-18140. [PMID: 32680014 DOI: 10.1364/oe.374383] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2019] [Accepted: 03/30/2020] [Indexed: 06/11/2023]
Abstract
We demonstrate a nonlinear light mode dispersion and a nonuniform frequency mode comb by a chirped fiber Bragg gratings (CFBG) Fabry-Perot (FP) at the 1550 nm wavelength regime. We give analytical expressions for the general chirp case, and an experimental demonstration with a linear chirp, showing a square-root dependence of the dispersion as a function of the FP mode number. Such sublinear dispersion is required, for example, for photon Bose-Einstein condensation (BEC) in a one-dimensional (1D) system like fiber cavities.
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7
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Kurtscheid C, Dung D, Busley E, Vewinger F, Rosch A, Weitz M. Thermally condensing photons into a coherently split state of light. Science 2019; 366:894-897. [PMID: 31727840 DOI: 10.1126/science.aay1334] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Revised: 09/23/2019] [Accepted: 10/23/2019] [Indexed: 11/02/2022]
Abstract
The quantum state of light plays a crucial role in a wide range of fields, from quantum information science to precision measurements. Whereas complex quantum states can be created for electrons in solid-state materials through mere cooling, optical manipulation and control builds on nonthermodynamic methods. Using an optical dye microcavity, we show that photon wave packets can be split through thermalization within a potential with two minima subject to tunnel coupling. At room temperature, photons condense into a quantum-coherent bifurcated ground state. Fringe signals upon recombination show the relative coherence between the two wells, demonstrating a working interferometer with the nonunitary thermodynamic beam splitter. Our energetically driven optical-state preparation method provides a route for exploring correlated and entangled optical many-body states.
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Affiliation(s)
- Christian Kurtscheid
- Institut für Angewandte Physik, Universität Bonn, Wegelerstraße 8, 53115 Bonn, Germany.
| | - David Dung
- Institut für Angewandte Physik, Universität Bonn, Wegelerstraße 8, 53115 Bonn, Germany
| | - Erik Busley
- Institut für Angewandte Physik, Universität Bonn, Wegelerstraße 8, 53115 Bonn, Germany
| | - Frank Vewinger
- Institut für Angewandte Physik, Universität Bonn, Wegelerstraße 8, 53115 Bonn, Germany
| | - Achim Rosch
- Institut für Theoretische Physik, Universität zu Köln, Zülpicher Straße 77, 50937 Cologne, Germany
| | - Martin Weitz
- Institut für Angewandte Physik, Universität Bonn, Wegelerstraße 8, 53115 Bonn, Germany.
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8
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Jeblick M, Leopold N, Pickl P. Derivation of the Time Dependent Gross-Pitaevskii Equation in Two Dimensions. COMMUNICATIONS IN MATHEMATICAL PHYSICS 2019; 372:1-69. [PMID: 32675823 PMCID: PMC7336254 DOI: 10.1007/s00220-019-03599-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/07/2017] [Accepted: 09/09/2019] [Indexed: 06/11/2023]
Abstract
We present microscopic derivations of the defocusing two-dimensional cubic nonlinear Schrödinger equation and the Gross-Pitaevskii equation starting from an interacting N-particle system of bosons. We consider the interaction potential to be given either byW β ( x ) = N - 1 + 2 β W ( N β x ) , for any β > 0 , or to be given byV N ( x ) = e 2 N V ( e N x ) , for some spherical symmetric, nonnegative and compactly supported W , V ∈ L ∞ ( R 2 , R ) . In both cases we prove the convergence of the reduced density corresponding to the exact time evolution to the projector onto the solution of the corresponding nonlinear Schrödinger equation in trace norm. For the latter potential V N we show that it is crucial to take the microscopic structure of the condensate into account in order to obtain the correct dynamics.
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Affiliation(s)
- Maximilian Jeblick
- Mathematisches Institut, Ludwig-Maximilians-Universität München, Theresienstraße 39, 80333 Munich, Germany
| | - Nikolai Leopold
- Institute of Science and Technology Austria (IST Austria), Am Campus 1, 3400 Klosterneuburg, Austria
| | - Peter Pickl
- Duke Kunshan University, Duke Avenue 8, Kunshan, 215316 China
- Ludwig-Maximilians-Universität München, Theresienstraße 39, 80333 Munich, Germany
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9
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Villegas KHA, Sun M, Kovalev VM, Savenko IG. Unconventional Bloch-Grüneisen Scattering in Hybrid Bose-Fermi Systems. PHYSICAL REVIEW LETTERS 2019; 123:095301. [PMID: 31524441 DOI: 10.1103/physrevlett.123.095301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Revised: 03/25/2019] [Indexed: 06/10/2023]
Abstract
We report on the novel mechanism of electron scattering in hybrid Bose-Fermi systems consisting of a two-dimensional electron gas in the vicinity of an exciton condensate: We show that in certain ranges of temperatures, the bogolon-pair-mediated scattering proves to be dominating over the conventional acoustic phonon channel, over the single-bogolon scattering, and over the scattering on impurities. We develop a microscopic theory of this effect, focusing on GaAs and MoS_{2} materials, and we find the principal temperature dependence of resistivity, distinct from the conventional phonon-mediated processes. Further, we scrutinize parameters and suggest a way to design composite samples with predefined electron mobilities, and we propose a mechanism of electron pairing for superconductivity.
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Affiliation(s)
- K H A Villegas
- Center for Theoretical Physics of Complex Systems, Institute for Basic Science (IBS), Daejeon 34126, Korea
| | - Meng Sun
- Center for Theoretical Physics of Complex Systems, Institute for Basic Science (IBS), Daejeon 34126, Korea
- Basic Science Program, Korea University of Science and Technology (UST), Daejeon 34113, Korea
| | - V M Kovalev
- A. V. Rzhanov Institute of Semiconductor Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
- Department of Applied and Theoretical Physics, Novosibirsk State Technical University, Novosibirsk 630073, Russia
| | - I G Savenko
- Center for Theoretical Physics of Complex Systems, Institute for Basic Science (IBS), Daejeon 34126, Korea
- Basic Science Program, Korea University of Science and Technology (UST), Daejeon 34113, Korea
- A. V. Rzhanov Institute of Semiconductor Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090, Russia
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10
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Weill R, Bekker A, Levit B, Fischer B. Bose-Einstein condensation of photons in an erbium-ytterbium co-doped fiber cavity. Nat Commun 2019; 10:747. [PMID: 30765701 PMCID: PMC6376030 DOI: 10.1038/s41467-019-08527-0] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2018] [Accepted: 01/16/2019] [Indexed: 11/09/2022] Open
Abstract
Bose-Einstein condensation (BEC) is a special many-boson phenomenon that was observed in atomic particles at ultra-low temperatures. Later, BEC was also shown for non-atomic bosons, such as photons. Those experiments were usually done in micron-size cavities, where the power (particle number) was varied, and not the temperature, until condensation was reached. Here we demonstrate BEC of photons in a few-meters-long one-dimensional (1D) erbium-ytterbium co-doped fiber cavity at, below and above room temperature, between 100 K and 415 K. The experiments were done at about the 1550 nm wavelength regime having a few to tens of μW intra-cavity light power (107-108 photons). By varying the power and also the temperature, we found linear dependence of the condensation on power for various temperatures and of the critical power (for condensation) on temperature. These findings agree, functionally and quantitatively, with the theoretical BEC prediction without any adjustable parameter.
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Affiliation(s)
- Rafi Weill
- The Andrew & Erna Viterbi Faculty of Electrical Engineering, Technion, 32000, Haifa, Israel
| | - Alexander Bekker
- The Andrew & Erna Viterbi Faculty of Electrical Engineering, Technion, 32000, Haifa, Israel
| | - Boris Levit
- The Andrew & Erna Viterbi Faculty of Electrical Engineering, Technion, 32000, Haifa, Israel
| | - Baruch Fischer
- The Andrew & Erna Viterbi Faculty of Electrical Engineering, Technion, 32000, Haifa, Israel.
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11
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Cecchini GG, Jones ACL, Fuentes-Garcia M, Adams DJ, Austin M, Membreno E, Mills AP. Detector for positronium temperature measurements by two-photon angular correlation. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:053106. [PMID: 29864868 DOI: 10.1063/1.5017724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
We report on the design and characterization of a modular γ-ray detector assembly developed for accurate and efficient detection of coincident 511 keV back-to-back γ-rays following electron-positron annihilation. Each modular detector consists of 16 narrow lutetium yttrium oxyorthosilicate scintillators coupled to a multi-anode Hamamatsu H12700B photomultiplier tube. We discuss the operation and optimization of 511 keV γ-ray detection resulting from testing various scintillators and detector arrangements concluding with an estimate of the coincident 511 keV detection efficiency for the intended experiment and a preliminary test representing one-quarter of the completed array.
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Affiliation(s)
- G G Cecchini
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - A C L Jones
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - M Fuentes-Garcia
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - D J Adams
- College of Natural and Agricultural Sciences Machine Shop, University of California, Riverside, California 92521, USA
| | - M Austin
- Department of Physics, Marquette University, Milwaukee, Wisconsin 53233, USA
| | - E Membreno
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - A P Mills
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
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12
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Damm T, Dung D, Vewinger F, Weitz M, Schmitt J. First-order spatial coherence measurements in a thermalized two-dimensional photonic quantum gas. Nat Commun 2017; 8:158. [PMID: 28761123 PMCID: PMC5537358 DOI: 10.1038/s41467-017-00270-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Accepted: 06/16/2017] [Indexed: 11/21/2022] Open
Abstract
Phase transitions between different states of matter can profoundly modify the order in physical systems, with the emergence of ferromagnetic or topological order constituting important examples. Correlations allow the quantification of the degree of order and the classification of different phases. Here we report measurements of first-order spatial correlations in a harmonically trapped two-dimensional photon gas below, at and above the critical particle number for Bose–Einstein condensation, using interferometric measurements of the emission of a dye-filled optical microcavity. For the uncondensed gas, the transverse coherence decays on a length scale determined by the thermal de Broglie wavelength of the photons, which shows the expected scaling with temperature. At the onset of Bose–Einstein condensation, true long-range order emerges, and we observe quantum statistical effects as the thermal wave packets overlap. The excellent agreement with equilibrium Bose gas theory prompts microcavity photons as promising candidates for studies of critical scaling and universality in optical quantum gases. Phase transitions in quantum matter are related to correlation effects and they can change the ordering of material. Here the authors measure the first-order spatial correlation and the de Broglie wavelength for both thermal and condensed form of a photonic Bose gas in a dye-filled optical microcavity.
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Affiliation(s)
- Tobias Damm
- Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, Bonn, 53115, Germany
| | - David Dung
- Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, Bonn, 53115, Germany
| | - Frank Vewinger
- Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, Bonn, 53115, Germany
| | - Martin Weitz
- Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, Bonn, 53115, Germany.
| | - Julian Schmitt
- Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, Bonn, 53115, Germany.
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13
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Dias WS, Bertrand D, Lyra ML. Bose-Einstein condensation in chains with power-law hoppings: Exact mapping on the critical behavior in d-dimensional regular lattices. Phys Rev E 2017; 95:062105. [PMID: 28709254 DOI: 10.1103/physreve.95.062105] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Indexed: 11/07/2022]
Abstract
Recent experimental progress on the realization of quantum systems with highly controllable long-range interactions has impelled the study of quantum phase transitions in low-dimensional systems with power-law couplings. Long-range couplings mimic higher-dimensional effects in several physical contexts. Here, we provide the exact relation between the spectral dimension d at the band bottom and the exponent α that tunes the range of power-law hoppings of a one-dimensional ideal lattice Bose gas. We also develop a finite-size scaling analysis to obtain some relevant critical exponents and the critical temperature of the BEC transition. In particular, an irrelevant dangerous scaling field has to be taken into account when the hopping range is sufficiently large to make the effective dimensionality d>4.
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Affiliation(s)
- W S Dias
- Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió, Alagoas, Brazil
| | - D Bertrand
- Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió, Alagoas, Brazil
| | - M L Lyra
- Instituto de Física, Universidade Federal de Alagoas, 57072-970 Maceió, Alagoas, Brazil
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14
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Martin AM, Marchant NG, O'Dell DHJ, Parker NG. Vortices and vortex lattices in quantum ferrofluids. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:103004. [PMID: 28145899 DOI: 10.1088/1361-648x/aa53a6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The experimental realization of quantum-degenerate Bose gases made of atoms with sizeable magnetic dipole moments has created a new type of fluid, known as a quantum ferrofluid, which combines the extraordinary properties of superfluidity and ferrofluidity. A hallmark of superfluids is that they are constrained to rotate through vortices with quantized circulation. In quantum ferrofluids the long-range dipolar interactions add new ingredients by inducing magnetostriction and instabilities, and also affect the structural properties of vortices and vortex lattices. Here we give a review of the theory of vortices in dipolar Bose-Einstein condensates, exploring the interplay of magnetism with vorticity and contrasting this with the established behaviour in non-dipolar condensates. We cover single vortex solutions, including structure, energy and stability, vortex pairs, including interactions and dynamics, and also vortex lattices. Our discussion is founded on the mean-field theory provided by the dipolar Gross-Pitaevskii equation, ranging from analytic treatments based on the Thomas-Fermi (hydrodynamic) and variational approaches to full numerical simulations. Routes for generating vortices in dipolar condensates are discussed, with particular attention paid to rotating condensates, where surface instabilities drive the nucleation of vortices, and lead to the emergence of rich and varied vortex lattice structures. We also present an outlook, including potential extensions to degenerate Fermi gases, quantum Hall physics, toroidal systems and the Berezinskii-Kosterlitz-Thouless transition.
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Affiliation(s)
- A M Martin
- School of Physics, University of Melbourne, Victoria 3010, Australia
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15
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Zhurahov M, Bekker A, Levit B, Weill R, Fischer B. CW laser light condensation. OPTICS EXPRESS 2016; 24:6553-6558. [PMID: 27136845 DOI: 10.1364/oe.24.006553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present a first experimental demonstration of classical CW laser light condensation (LC) in the frequency (mode) domain that verifies its prediction (Fischer and Weill, Opt. Express20, 26704 (2012)). LC is based on weighting the modes in a noisy environment in a loss-gain measure compared to an energy (frequency) scale in Bose-Einstein condensation (BEC). It is characterized by a sharp transition from multi- to single-mode oscillation, occurring when the spectral-filtering (loss-trap) has near the lowest-loss mode ("ground-state") a power-law dependence with an exponent smaller than 1. An important meaning of the many-mode LC system stems from its relation to lasing and photon-BEC.
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16
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Kosterlitz JM. Kosterlitz-Thouless physics: a review of key issues. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2016; 79:026001. [PMID: 26824490 DOI: 10.1088/0034-4885/79/2/026001] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
This article reviews, from a very personal point of view, the origins and the early work on transitions driven by topological defects such as vortices in the two dimensional planar rotor model and in (4)Helium films and dislocations and disclinations in 2D crystals. I cover the early papers with David Thouless and describe the important insights but also the errors and oversights since corrected by other workers. I then describe some of the experimental verifications of the theory and some numerical simulations. Finally applications to superconducting arrays of Josephson junctions and to recent cold atom experiments are described.
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17
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Schmitt J, Damm T, Dung D, Wahl C, Vewinger F, Klaers J, Weitz M. Spontaneous Symmetry Breaking and Phase Coherence of a Photon Bose-Einstein Condensate Coupled to a Reservoir. PHYSICAL REVIEW LETTERS 2016; 116:033604. [PMID: 26849597 DOI: 10.1103/physrevlett.116.033604] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2015] [Indexed: 06/05/2023]
Abstract
We examine the phase evolution of a Bose-Einstein condensate of photons generated in a dye microcavity by temporal interference with a phase reference. The photoexcitable dye molecules constitute a reservoir of variable size for the condensate particles, allowing for grand canonical statistics with photon bunching, as in a lamp-type source. We directly observe phase jumps of the condensate associated with the large statistical number fluctuations and find a separation of correlation time scales. For large systems, our data reveal phase coherence and a spontaneously broken symmetry, despite the statistical fluctuations.
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Affiliation(s)
- Julian Schmitt
- Institut für Angewandte Physik, Universität Bonn, Wegelerstrasse 8, 53115 Bonn, Germany
| | - Tobias Damm
- Institut für Angewandte Physik, Universität Bonn, Wegelerstrasse 8, 53115 Bonn, Germany
| | - David Dung
- Institut für Angewandte Physik, Universität Bonn, Wegelerstrasse 8, 53115 Bonn, Germany
| | - Christian Wahl
- Institut für Angewandte Physik, Universität Bonn, Wegelerstrasse 8, 53115 Bonn, Germany
| | - Frank Vewinger
- Institut für Angewandte Physik, Universität Bonn, Wegelerstrasse 8, 53115 Bonn, Germany
| | - Jan Klaers
- Institut für Angewandte Physik, Universität Bonn, Wegelerstrasse 8, 53115 Bonn, Germany
| | - Martin Weitz
- Institut für Angewandte Physik, Universität Bonn, Wegelerstrasse 8, 53115 Bonn, Germany
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Kaputkina N, Lozovik Y, Altaisky M. Spontaneous Coherence Effects in Quantum Dots and Quantum Wells Placed in Microcavities. EPJ WEB OF CONFERENCES 2016. [DOI: 10.1051/epjconf/201610802031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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19
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Li H, Guo Q, Jiang J, Johnston DC. Thermodynamics of the noninteracting Bose gas in a two-dimensional box. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:062109. [PMID: 26764634 DOI: 10.1103/physreve.92.062109] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2015] [Indexed: 06/05/2023]
Abstract
Bose-Einstein condensation (BEC) of a noninteracting Bose gas of N particles in a two-dimensional box with Dirichlet boundary conditions is studied. Confirming previous work, we find that BEC occurs at finite N at low temperatures T without the occurrence of a phase transition. The conventionally-defined transition temperature T(E) for an infinite three-dimensional (3D) system is shown to correspond in a 2D system with finite N to a crossover temperature between a slow and rapid increase in the fractional boson occupation N(0)/N of the ground state with decreasing T. We further show that T(E)∼1/logN at fixed area per boson, so in the thermodynamic limit there is no significant BEC in 2D at finite T. Thus, paradoxically, BEC only occurs in 2D at finite N with no phase transition associated with it. Calculations of thermodynamic properties versus T and area A are presented, including Helmholtz free energy, entropy S, pressure p, ratio of p to the energy density U/A, heat capacity at constant volume (area) C(V) and at constant pressure C(p), isothermal compressibility κ(T) and thermal expansion coefficient α(p), obtained using both the grand-canonical ensemble (GCE) and canonical ensemble (CE) formalisms. The GCE formalism gives acceptable predictions for S, p, p/(U/A), κ(T) and α(p) at large N, T and A but fails for smaller values of these three parameters for which BEC becomes significant, whereas the CE formalism gives accurate results for all thermodynamic properties of finite systems even at low T and/or A where BEC occurs.
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Affiliation(s)
- Heqiu Li
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Qiujiang Guo
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - Ji Jiang
- Department of Physics, Zhejiang University, Hangzhou 310027, China
| | - D C Johnston
- Department of Physics and Astronomy and Ames Laboratory, Iowa State University, Ames, Iowa 50011, USA
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Bose–Einstein Condensation of Atoms and Photons. PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES INDIA SECTION A-PHYSICAL SCIENCES 2015. [DOI: 10.1007/s40010-015-0254-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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21
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Olendski O. Comparative analysis of electric field influence on the quantum wells with different boundary conditions: II. Thermodynamic properties. ANNALEN DER PHYSIK 2015; 527:296-310. [PMID: 25914414 PMCID: PMC4402035 DOI: 10.1002/andp.201400229] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/29/2014] [Revised: 02/09/2015] [Accepted: 02/10/2015] [Indexed: 06/04/2023]
Abstract
Thermodynamic properties of the one-dimensional (1D) quantum well (QW) with miscellaneous permutations of the Dirichlet (D) and Neumann (N) boundary conditions (BCs) at its edges in the perpendicular to the surfaces electric field [Formula: see text] are calculated. For the canonical ensemble, analytical expressions involving theta functions are found for the mean energy and heat capacity [Formula: see text] for the box with no applied voltage. Pronounced maximum accompanied by the adjacent minimum of the specific heat dependence on the temperature T for the pure Neumann QW and their absence for other BCs are predicted and explained by the structure of the corresponding energy spectrum. Applied field leads to the increase of the heat capacity and formation of the new or modification of the existing extrema what is qualitatively described by the influence of the associated electric potential. A remarkable feature of the Fermi grand canonical ensemble is, at any BC combination in zero fields, a salient maximum of [Formula: see text] observed on the T axis for one particle and its absence for any other number N of corpuscles. Qualitative and quantitative explanation of this phenomenon employs the analysis of the chemical potential and its temperature dependence for different N. It is proved that critical temperature [Formula: see text] of the Bose-Einstein (BE) condensation increases with the applied voltage for any number of particles and for any BC permutation except the ND case at small intensities [Formula: see text] what is explained again by the modification by the field of the interrelated energies. It is shown that even for the temperatures smaller than [Formula: see text] the total dipole moment [Formula: see text] may become negative for the quite moderate [Formula: see text]. For either Fermi or BE system, the influence of the electric field on the heat capacity is shown to be suppressed with N growing. Different asymptotic cases of, e.g., the small and large temperatures and low and high voltages are derived analytically and explained physically. Parallels are drawn to the similar properties of the 1D harmonic oscillator, and similarities and differences between them are discussed.
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Affiliation(s)
- Oleg Olendski
- King Abdullah Institute for Nanotechnology, King Saud UniversityP.O. Box 2455, Riyadh, 11451, Saudi Arabia
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22
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Kirton P, Keeling J. Nonequilibrium model of photon condensation. PHYSICAL REVIEW LETTERS 2013; 111:100404. [PMID: 25166637 DOI: 10.1103/physrevlett.111.100404] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Indexed: 06/03/2023]
Abstract
We develop a nonequilibrium model of condensation and lasing of photons in a dye filled microcavity. We examine in detail the nature of the thermalization process induced by absorption and emission of photons by the dye molecules, and investigate when the photons are able to reach a thermal equilibrium Bose-Einstein distribution. At low temperatures, or large cavity losses, the absorption and emission rates are too small to allow the photons to reach thermal equilibrium and the behavior becomes more like that of a conventional laser.
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Affiliation(s)
- Peter Kirton
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, United Kingdom
| | - Jonathan Keeling
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, United Kingdom
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23
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Sob'yanin DN. Bose-Einstein condensation of light: general theory. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:022132. [PMID: 24032800 DOI: 10.1103/physreve.88.022132] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Indexed: 06/02/2023]
Abstract
A theory of Bose-Einstein condensation of light in a dye-filled optical microcavity is presented. The theory is based on the hierarchical maximum entropy principle and allows one to investigate the fluctuating behavior of the photon gas in the microcavity for all numbers of photons, dye molecules, and excitations at all temperatures, including the whole critical region. The master equation describing the interaction between photons and dye molecules in the microcavity is derived and the equivalence between the hierarchical maximum entropy principle and the master equation approach is shown. The cases of a fixed mean total photon number and a fixed total excitation number are considered, and a much sharper, nonparabolic onset of a macroscopic Bose-Einstein condensation of light in the latter case is demonstrated. The theory does not use the grand canonical approximation, takes into account the photon polarization degeneracy, and exactly describes the microscopic, mesoscopic, and macroscopic Bose-Einstein condensation of light. Under certain conditions, it predicts sub-Poissonian statistics of the photon condensate and the polarized photon condensate, and a universal relation takes place between the degrees of second-order coherence for these condensates. In the macroscopic case, there appear a sharp jump in the degrees of second-order coherence, a sharp jump and kink in the reduced standard deviations of the fluctuating numbers of photons in the polarized and whole condensates, and a sharp peak, a cusp, of the Mandel parameter for the whole condensate in the critical region. The possibility of nonclassical light generation in the microcavity with the photon Bose-Einstein condensate is predicted.
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Affiliation(s)
- Denis Nikolaevich Sob'yanin
- Tamm Department of Theoretical Physics, Lebedev Physical Institute, Russian Academy of Sciences, Leninskii Prospekt 53, Moscow, 119991 Russia
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Choi JY, Seo SW, Shin YI. Observation of thermally activated vortex pairs in a quasi-2D Bose gas. PHYSICAL REVIEW LETTERS 2013; 110:175302. [PMID: 23679741 DOI: 10.1103/physrevlett.110.175302] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2013] [Indexed: 06/02/2023]
Abstract
We measure the in-plane distribution of thermally activated vortices in a trapped quasi-2D Bose gas, where we enhance the visibility of density-depleted vortex cores by radially compressing the sample before releasing the trap. The pairing of vortices is revealed by the two-vortex spatial correlation function obtained from the vortex distribution. The vortex density decreases gradually as temperature is lowered, and below a certain temperature, a vortex-free region emerges in the center of the sample. This shows the crossover from a Berezinskii-Kosterlitz-Thouless phase containing vortex-pair excitations to a vortex-free Bose-Einstein condensate in a finite-size 2D system.
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Affiliation(s)
- Jae-yoon Choi
- Center for Subwavelength Optics and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
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25
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Braun S, Ronzheimer JP, Schreiber M, Hodgman SS, Rom T, Bloch I, Schneider U. Negative Absolute Temperature for Motional Degrees of Freedom. Science 2013; 339:52-5. [DOI: 10.1126/science.1227831] [Citation(s) in RCA: 158] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- S. Braun
- Fakultät für Physik, Ludwig-Maximilians-Universität München, Schellingstraße 4, 80799 Munich, Germany
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching, Germany
| | - J. P. Ronzheimer
- Fakultät für Physik, Ludwig-Maximilians-Universität München, Schellingstraße 4, 80799 Munich, Germany
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching, Germany
| | - M. Schreiber
- Fakultät für Physik, Ludwig-Maximilians-Universität München, Schellingstraße 4, 80799 Munich, Germany
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching, Germany
| | - S. S. Hodgman
- Fakultät für Physik, Ludwig-Maximilians-Universität München, Schellingstraße 4, 80799 Munich, Germany
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching, Germany
| | - T. Rom
- Fakultät für Physik, Ludwig-Maximilians-Universität München, Schellingstraße 4, 80799 Munich, Germany
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching, Germany
| | - I. Bloch
- Fakultät für Physik, Ludwig-Maximilians-Universität München, Schellingstraße 4, 80799 Munich, Germany
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching, Germany
| | - U. Schneider
- Fakultät für Physik, Ludwig-Maximilians-Universität München, Schellingstraße 4, 80799 Munich, Germany
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Straße 1, 85748 Garching, Germany
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Sob'yanin DN. Hierarchical maximum entropy principle for generalized superstatistical systems and Bose-Einstein condensation of light. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2012; 85:061120. [PMID: 23005064 DOI: 10.1103/physreve.85.061120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2012] [Indexed: 06/01/2023]
Abstract
A principle of hierarchical entropy maximization is proposed for generalized superstatistical systems, which are characterized by the existence of three levels of dynamics. If a generalized superstatistical system comprises a set of superstatistical subsystems, each made up of a set of cells, then the Boltzmann-Gibbs-Shannon entropy should be maximized first for each cell, second for each subsystem, and finally for the whole system. Hierarchical entropy maximization naturally reflects the sufficient time-scale separation between different dynamical levels and allows one to find the distribution of both the intensive parameter and the control parameter for the corresponding superstatistics. The hierarchical maximum entropy principle is applied to fluctuations of the photon Bose-Einstein condensate in a dye microcavity. This principle provides an alternative to the master equation approach recently applied to this problem. The possibility of constructing generalized superstatistics based on a statistics different from the Boltzmann-Gibbs statistics is pointed out.
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Affiliation(s)
- Denis Nikolaevich Sob'yanin
- Tamm Department of Theoretical Physics, Lebedev Physical Institute, Russian Academy of Sciences, Leninskii Prospekt 53, Moscow, 119991 Russia.
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27
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Klaers J, Schmitt J, Damm T, Vewinger F, Weitz M. Statistical physics of Bose-Einstein-condensed light in a dye microcavity. PHYSICAL REVIEW LETTERS 2012; 108:160403. [PMID: 22680703 DOI: 10.1103/physrevlett.108.160403] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2011] [Indexed: 06/01/2023]
Abstract
We theoretically analyze the temperature behavior of paraxial light in thermal equilibrium with a dye-filled optical microcavity. At low temperatures the photon gas undergoes Bose-Einstein condensation, and the photon number in the cavity ground state becomes macroscopic with respect to the total photon number. Owing to a grand-canonical excitation exchange between the photon gas and the dye molecule reservoir, a regime with unusually large fluctuations of the condensate number is predicted for this system that is not observed in present atomic physics Bose-Einstein condensation experiments.
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Affiliation(s)
- Jan Klaers
- Institut für Angewandte Physik, Universität Bonn, Wegelerstrasse 8, 53115 Bonn, Germany
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28
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Bittner ER, Silva C. Estimating the conditions for polariton condensation in organic thin-film microcavities. J Chem Phys 2012; 136:034510. [PMID: 22280770 DOI: 10.1063/1.3678015] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
We examine the possibility of observing Bose condensation of a confined two-dimensional polariton gas in an organic quantum well. We deduce a suitable parameterization of a model polynomial Hamiltonian based upon the cavity geometry, the biexciton binding energy, and similar spectroscopic and structural data. By converting the sum-over-states to a semiclassical integration over D-dimensional phase space, we arrive at a principle of correspondence between ideal and non-ideal Bose gases that share a common critical exponent. Using our results, we can calculate the properties for a model cavity containing an anthracene thin film.
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Affiliation(s)
- Eric R Bittner
- Department of Chemistry, University of Houston, Houston, Texas 77204, USA.
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29
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Berman OL, Kezerashvili RY, Lozovik YE, Snoke DW. Bose-Einstein condensation and superfluidity of trapped polaritons in graphene and quantum wells embedded in a microcavity. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2010; 368:5459-5482. [PMID: 21041225 DOI: 10.1098/rsta.2010.0208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The theory for spontaneous coherence of short-lived quasiparticles in two-dimensional excitonic systems is reviewed, in particular, quantum wells (QWs) and graphene layers (GLs) embedded in microcavities. Experiments with polaritons in an optical microcavity have already shown evidence of Bose-Einstein condensation (BEC) in the lowest quantum state in a harmonic trap. The theory of BEC and superfluidity of the microcavity excitonic polaritons in a harmonic potential trap is presented. Along the way, we determine a general method for defining the superfluid fraction in a two-dimensional trap, within the angular momentum representation. We discuss BEC of magnetoexcitonic polaritons (magnetopolaritons) in a QW and GL embedded in an optical microcavity in high magnetic field. It is shown that Rabi splitting in graphene is tunable by the external magnetic field B, while in a QW the Rabi splitting does not depend on the magnetic field in the strong B limit.
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Affiliation(s)
- Oleg L Berman
- Physics Department, New York City College of Technology, City University of New York, Brooklyn, NY 11201, USA.
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Tung S, Lamporesi G, Lobser D, Xia L, Cornell EA. Observation of the presuperfluid regime in a two-dimensional Bose gas. PHYSICAL REVIEW LETTERS 2010; 105:230408. [PMID: 21231437 DOI: 10.1103/physrevlett.105.230408] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2010] [Revised: 09/14/2010] [Indexed: 05/30/2023]
Abstract
In complementary images of coordinate-space and momentum-space density in a trapped 2D Bose gas, we observe the emergence of presuperfluid behavior. As phase-space density ρ increases toward degenerate values, we observe a gradual divergence of the compressibility κ from the value predicted by a bare-atom model, κ(ba). κ/κ(ba) grows to 1.7 before ρ reaches the value for which we observe the sudden emergence of a spike at p = 0 in momentum space. Momentum-space images are acquired by means of a 2D focusing technique. Our data represent the first observation of non-mean-field physics in the presuperfluid but degenerate 2D Bose gas.
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Affiliation(s)
- S Tung
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440, USA
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31
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Klaers J, Schmitt J, Vewinger F, Weitz M. Bose–Einstein condensation of photons in an optical microcavity. Nature 2010; 468:545-8. [DOI: 10.1038/nature09567] [Citation(s) in RCA: 489] [Impact Index Per Article: 34.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Accepted: 10/06/2010] [Indexed: 11/09/2022]
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Weill R, Levit B, Bekker A, Gat O, Fischer B. Laser light condensate: experimental demonstration of light-mode condensation in actively mode locked laser. OPTICS EXPRESS 2010; 18:16520-16525. [PMID: 20721041 DOI: 10.1364/oe.18.016520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
We have recently predicted (R. Weill, B. Fischer and O. Gat, Phys. Rev. Lett.104, 173901, 2010) condensation of light in actively mode locked lasers when the laser power increases, or the noise, that takes the role of temperature, decreases. The condensate is characterized by strong light pulses due to the dominance of the lowest eigenmode ("ground state") power. Here, we experimentally demonstrate, for the first time, light mode condensation transition in an actively mode-locked fiber laser. Following the theoretical prediction, the condensation is obtained for modulations that have a power law dependence on time with exponents smaller than 2. The laser light system is strictly one dimensional, a special opportunity in experimental physics. We also discuss experimental schemes for condensation in two- and three-dimensional laser systems.
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Affiliation(s)
- Rafi Weill
- 1Max-Planck Institute for Polymer Research, Mainz 55128, Germany
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33
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Weill R, Fischer B, Gat O. Light-mode condensation in actively-mode-locked lasers. PHYSICAL REVIEW LETTERS 2010; 104:173901. [PMID: 20482109 DOI: 10.1103/physrevlett.104.173901] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2009] [Indexed: 05/29/2023]
Abstract
We show that the formation of pulses in actively mode-locked lasers exhibits in certain conditions a transition of the laser mode system to a light pulse state that is similar to Bose-Einstein condensation (BEC). The study is done in the framework of statistical light-mode dynamics with a mapping between the distribution of the laser eigenmodes to the equilibrium statistical physics of noninteracting bosons in an external potential. The light-mode BEC transition occurs for a mode-locking modulation that has a power law dependence on time with an exponent smaller than 2.
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Affiliation(s)
- Rafi Weill
- Department of Electrical Engineering, Technion-IIT, Haifa 32000, Israel
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Berman OL, Kezerashvili RY, Lozovik YE. Bose-Einstein condensation of quasiparticles in graphene. NANOTECHNOLOGY 2010; 21:134019. [PMID: 20208112 DOI: 10.1088/0957-4484/21/13/134019] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The collective properties of different quasiparticles in various graphene-based structures in a high magnetic field have been studied. We predict Bose-Einstein condensation (BEC) and the superfluidity of 2D spatially indirect magnetoexcitons in a two-layer graphene. The superfluid density and the temperature of the Kosterlitz-Thouless phase transition are shown to be increasing functions of the excitonic density but decreasing functions of a magnetic field and the interlayer separation. The instability of the ground state of the interacting 2D indirect magnetoexcitons in a slab of superlattice with alternating electron and hole graphene layers (GLs) is established. The stable system of indirect 2D magnetobiexcitons, consisting of a pair of indirect excitons with antiparallel dipole moments, is considered in a graphene superlattice. The superfluid density and the temperature of the Kosterlitz-Thouless phase transition for magnetobiexcitons in a graphene superlattice are obtained. Moreover, the BEC of excitonic polaritons in a GL embedded in a semiconductor microcavity in a high magnetic field is predicted. While the superfluid phase in this magnetoexciton polariton system is absent due to a vanishing magnetoexciton-magnetoexciton interaction in a single layer in the limit of a high magnetic field, the critical temperature of the BEC formation is calculated. The observation of the BEC and superfluidity of 2D quasiparticles in graphene in a high magnetic field would be interesting confirmation of the phenomena we have described.
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Affiliation(s)
- Oleg L Berman
- Physics Department, New York City College of Technology, The City University of New York, Brooklyn, NY 11201, USA
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35
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Gallego D, Hofferberth S, Schumm T, Krüger P, Schmiedmayer J. Optical lattice on an atom chip. OPTICS LETTERS 2009; 34:3463-3465. [PMID: 19927178 DOI: 10.1364/ol.34.003463] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
Optical dipole traps and atom chips are two very powerful tools for the quantum manipulation of neutral atoms. We demonstrate that both methods can be combined by creating an optical lattice potential on an atom chip. A red-detuned laser beam is retroreflected using the atom chip surface as a high-quality mirror, generating a vertical array of purely optical oblate traps. We transfer thermal atoms from the chip into the lattice and observe cooling into the two-dimensional regime. Using a chip-generated Bose-Einstein condensate, we demonstrate coherent Bloch oscillations in the lattice.
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Affiliation(s)
- D Gallego
- Physikalisches Institut, Universität Heidelberg, 69120 Heidelberg, Germany
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36
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Cladé P, Ryu C, Ramanathan A, Helmerson K, Phillips WD. Observation of a 2D Bose gas: from thermal to quasicondensate to superfluid. PHYSICAL REVIEW LETTERS 2009; 102:170401. [PMID: 19518764 DOI: 10.1103/physrevlett.102.170401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2008] [Indexed: 05/27/2023]
Abstract
We present experimental results on a Bose gas in a quasi-2D geometry near the Berezinskii, Kosterlitz, and Thouless (BKT) transition temperature. By measuring the density profile after time of flight and the coherence length, we identify different states of the gas. We observe that the gas develops a bimodal distribution without long range order. In this regime, the gas presents a longer coherence length than the thermal cloud; it is quasicondensed but is not superfluid. Experimental evidence indicates that we also observe the superfluid transition (BKT transition). For a sufficiently long time of flight, we observe a trimodal distribution when the gas has developed a superfluid component.
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Affiliation(s)
- P Cladé
- Atomic Physics Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8424, USA
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38
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Yao W, Niu Q. Berry phase effect on the exciton transport and on the exciton Bose-Einstein condensate. PHYSICAL REVIEW LETTERS 2008; 101:106401. [PMID: 18851231 DOI: 10.1103/physrevlett.101.106401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/08/2008] [Revised: 07/23/2008] [Indexed: 05/26/2023]
Abstract
With the exciton lifetime much extended in semiconductor quantum-well structures, the exciton transport and Bose-Einstein condensation have become a focus of research in recent years. We reveal a momentum-space gauge field in the exciton center-of-mass dynamics due to Berry phase effects. We predict a spin-dependent transport of the excitons analogous to the anomalous Hall and Nernst effects for electrons. We also predict spin-dependent circulation of a trapped exciton gas and instability in an exciton condensate in favor of vortex formation.
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Affiliation(s)
- Wang Yao
- Department of Physics, The University of Texas, Austin, Texas 78712, USA.
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39
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Holzmann M, Krauth W. Kosterlitz-Thouless transition of the quasi-two-dimensional trapped Bose gas. PHYSICAL REVIEW LETTERS 2008; 100:190402. [PMID: 18518427 DOI: 10.1103/physrevlett.100.190402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2007] [Revised: 03/06/2008] [Indexed: 05/26/2023]
Abstract
We use quantum Monte Carlo methods to compute the density profile, the nonclassical moment of inertia, and the condensate fraction of an interacting quasi-two-dimensional trapped Bose gas with up to N ~ 5 x 10(5) atoms and parameters closely related to recent experiments. We locate the Kosterlitz-Thouless temperature T(KT) and discuss intrinsic signatures of the onset of superfluidity in the density profile. Below T(KT), the condensate fraction is macroscopic even for our largest systems and decays only slowly with system size. We show that the thermal population of excited states in the transverse direction changes the two-dimensional density profile noticeably in both the normal and the superfluid phase.
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40
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Deng H, Solomon GS, Hey R, Ploog KH, Yamamoto Y. Spatial coherence of a polariton condensate. PHYSICAL REVIEW LETTERS 2007; 99:126403. [PMID: 17930529 DOI: 10.1103/physrevlett.99.126403] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2007] [Indexed: 05/25/2023]
Abstract
We perform Young's double-slit experiment to study the spatial coherence properties of a two-dimensional dynamic condensate of semiconductor microcavity polaritons. The coherence length of the system is measured as a function of the pump rate, which confirms a spontaneous buildup of macroscopic coherence in the condensed phase. An independent measurement reveals that the position and momentum uncertainty product of the condensate is close to the Heisenberg limit. An experimental realization of such a minimum uncertainty wave packet of the polariton condensate opens a door to coherent matter-wave phenomena such as Josephson oscillation, superfluidity, and solitons in solid state condensate systems.
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Affiliation(s)
- Hui Deng
- Edward L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA
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41
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Krüger P, Hadzibabic Z, Dalibard J. Critical point of an interacting two-dimensional atomic Bose gas. PHYSICAL REVIEW LETTERS 2007; 99:040402. [PMID: 17678340 DOI: 10.1103/physrevlett.99.040402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Indexed: 05/16/2023]
Abstract
We have measured the critical atom number in an array of harmonically trapped two-dimensional (2D) Bose gases of rubidium atoms at different temperatures. We found this number to be about 5 times higher than predicted by the semiclassical theory of Bose-Einstein condensation (BEC) in the ideal gas. This demonstrates that the conventional BEC picture is inapplicable in an interacting 2D atomic gas, in sharp contrast to the three-dimensional case. A simple heuristic model based on the Berezinskii-Kosterlitz-Thouless theory of 2D superfluidity and the local density approximation accounts well for our experimental results.
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Affiliation(s)
- Peter Krüger
- Laboratoire Kastler Brossel and CNRS, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France
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43
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Savona V. Effect of interface disorder on quantum well excitons and microcavity polaritons. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2007; 19:295208. [PMID: 21483060 DOI: 10.1088/0953-8984/19/29/295208] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
Abstract
The theory of the linear optical response of excitons in quantum wells and polaritons in planar semiconductor microcavities is reviewed, in the light of the existing experiments. For quantum well excitons, it is shown that disorder mainly affects the exciton centre-of-mass motion and is modelled by an effective Schrödinger equation in two dimensions. For polaritons, a unified model accounting for quantum well roughness and fluctuations of the microcavity thickness is developed. Numerical results confirm that polaritons are mostly affected by disorder acting on the photon component, thus confirming existing studies on the influence of exciton disorder. The polariton localization length is estimated to be in the few-micrometres range, depending on the amplitude of disorder, in agreement with recent experimental findings.
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Affiliation(s)
- Vincenzo Savona
- Institut de Théorie des Phénomènes Physiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
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44
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Potter GG, Müller G, Karbach M. Thermodynamics of ideal quantum gas with fractional statistics in D dimensions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:061120. [PMID: 17677233 DOI: 10.1103/physreve.75.061120] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2006] [Indexed: 05/16/2023]
Abstract
We present exact and explicit results for the thermodynamic properties (isochores, isotherms, isobars, response functions, velocity of sound) of a quantum gas in dimensions D > or = 1 and with fractional exclusion statistics 0 < or = g < or =1 connecting bosons (g=0) and fermions (g=1) . In D=1 the results are equivalent to those of the Calogero-Sutherland model. Emphasis is given to the crossover between bosonlike and fermionlike features, caused by aspects of the statistical interaction that mimic long-range attraction and short-range repulsion. A phase transition along the isobar occurs at a nonzero temperature in all dimensions. The T dependence of the velocity of sound is in simple relation to isochores and isobars. The effects of soft container walls are accounted for rigorously for the case of a pure power-law potential.
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Affiliation(s)
- Geoffrey G Potter
- Department of Physics, University of Rhode Island, Kingston, Rhode Island 02881, USA
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Malpuech G, Solnyshkov DD, Ouerdane H, Glazov MM, Shelykh I. Bose glass and superfluid phases of cavity polaritons. PHYSICAL REVIEW LETTERS 2007; 98:206402. [PMID: 17677719 DOI: 10.1103/physrevlett.98.206402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2007] [Indexed: 05/16/2023]
Abstract
We report the calculation of cavity exciton-polariton phase diagram including realistic structural disorder. With increasing density polaritons first undergo a quasiphase transition toward a Bose glass: the condensate is localized in at least one minimum of the disorder potential. A further increase of the density leads to a percolation process of the polariton fluid giving rise to a Kosterlitz-Thouless phase transition toward superfluidity. The spatial representation of the condensate wave function as well as the spectrum of elementary excitations are obtained from the Gross-Pitaevskii equation for all the phases.
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Affiliation(s)
- G Malpuech
- LASMEA, CNRS-Université Blaise Pascal, 24 Avenue des Landais, 63177 Aubière Cedex France
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46
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Springall R, Per M, Snook I. Evaluation of the permutational structure of quantum gases at finite temperature. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2007; 75:031124. [PMID: 17500685 DOI: 10.1103/physreve.75.031124] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/13/2006] [Indexed: 05/15/2023]
Abstract
Proposed is an alternative method for permutational sampling in quantum gases using the path integral formulation of statistical mechanics. It is shown that in principle we are able to use two operators which enable us to construct a Markov chain through a graph of the irreducible representation of the symmetric group. As an illustration of this method, a test calculation of four particles in a harmonic trap is performed.
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Affiliation(s)
- Ryan Springall
- Department of Physics, RMIT University, Melbourne, Australia 3001.
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Holzmann M, Baym G, Blaizot JP, Laloë F. Superfluid transition of homogeneous and trapped two-dimensional Bose gases. Proc Natl Acad Sci U S A 2007; 104:1476-81. [PMID: 17244706 PMCID: PMC1785267 DOI: 10.1073/pnas.0609957104] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Current experiments on atomic gases in highly anisotropic traps present the opportunity to study in detail the low temperature phases of two-dimensional inhomogeneous systems. Although, in an ideal gas, the trapping potential favors Bose-Einstein condensation at finite temperature, interactions tend to destabilize the condensate, leading to a superfluid Kosterlitz-Thouless-Berezinskii phase with a finite superfluid mass density but no long-range order, as in homogeneous fluids. The transition in homogeneous systems is conveniently described in terms of dissociation of topological defects (vortex-antivortex pairs). However, trapped two-dimensional gases are more directly approached by generalizing the microscopic theory of the homogeneous gas. In this paper, we first derive, via a diagrammatic expansion, the scaling structure near the phase transition in a homogeneous system, and then study the effects of a trapping potential in the local density approximation. We find that a weakly interacting trapped gas undergoes a Kosterlitz-Thouless-Berezinskii transition from the normal state at a temperature slightly below the Bose-Einstein transition temperature of the ideal gas. The characteristic finite superfluid mass density of a homogeneous system just below the transition becomes strongly suppressed in a trapped gas.
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Affiliation(s)
- Markus Holzmann
- Laboratoire de Physique Théorique de la Matière Condensée, Unité Mixte de Recherche, Centre National de la Recherche Scientifique 7600, Université Pierre et Marie Curie, 4 Place Jussieu, 75005 Paris, France
| | - Gordon Baym
- Department of Physics, University of Illinois at Urbana–Champaign, 1110 West Green Street, Urbana, IL 61801
- To whom correspondence should be addressed. E-mail:
| | - Jean-Paul Blaizot
- European Centre for Theoretical Studies in Nuclear Physics and Related Areas, 38050 Villazzano (Trento), Italy
- Service de Physique Théorique, Commissariat à l'Energie Atomique–Saclay, Orme des Merisiers, 91191 Gif-sur-Yvette, France; and
| | - Franck Laloë
- Laboratoire Kastler Brossel, Ecole Normal Supérieure, 24 rue Lhomond, 75005 Paris, France
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48
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Trebbia JB, Esteve J, Westbrook CI, Bouchoule I. Experimental evidence for the breakdown of a Hartree-Fock approach in a weakly interacting Bose gas. PHYSICAL REVIEW LETTERS 2006; 97:250403. [PMID: 17280332 DOI: 10.1103/physrevlett.97.250403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2006] [Indexed: 05/13/2023]
Abstract
We investigate the physics underlying the presence of a quasicondensate in a nearly one dimensional, weakly interacting trapped atomic Bose gas. We show that a Hartree-Fock (mean-field) approach fails to predict the existence of the quasicondensate in the center of the cloud: the quasicondensate is generated by interaction-induced correlations between atoms and not by a saturation of the excited states. Numerical calculations based on Bogoliubov theory give an estimate of the crossover density in agreement with experimental results.
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Affiliation(s)
- J-B Trebbia
- Laboratoire Charles Fabry, CNRS et Université Paris 11, 91403 Orsay CEDEX, France
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49
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Vörös Z, Snoke DW, Pfeiffer L, West K. Trapping excitons in a two-dimensional in-plane harmonic potential: experimental evidence for equilibration of indirect excitons. PHYSICAL REVIEW LETTERS 2006; 97:016803. [PMID: 16907396 DOI: 10.1103/physrevlett.97.016803] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2006] [Indexed: 05/11/2023]
Abstract
We have trapped a gas of long-lifetime, high-mobility excitons in an in-plane harmonic potential. Trapping is an important step toward the goal of a controlled Bose-Einstein condensate of excitons. We show that the repulsive interaction between the excitons plays a dominant role in the behavior of the excitons, in contrast with the weak interactions in atomic gases. We show that under proper conditions the excitons thermalize in the trap to a well-defined equilibrium spatial distribution.
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Affiliation(s)
- Z Vörös
- Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260, USA
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