1
|
Spada G, Pilati S, Giorgini S. Quantum Droplets in Two-Dimensional Bose Mixtures at Finite Temperature. PHYSICAL REVIEW LETTERS 2024; 133:083401. [PMID: 39241715 DOI: 10.1103/physrevlett.133.083401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/20/2024] [Accepted: 07/18/2024] [Indexed: 09/09/2024]
Abstract
We investigate the formation of quantum droplets at finite temperature in attractive Bose mixtures subject to a strong transverse harmonic confinement. By means of exact path-integral Monte Carlo methods we determine the equilibrium density of the gas and the liquid as well as the pressure vs volume dependence along isothermal curves. Results for the equation of state and for the gas-liquid coexistence region in quasi-2D configurations are compared with calculations in strictly two dimensions, finding excellent agreement. Within the pure 2D model we explore the relevance of the quantum scale anomaly and we determine the critical interaction strength for the occurrence of the first-order gas to liquid transition. Furthermore, we find that the superfluid response develops suddenly, following the density jump from the gas to the liquid state.
Collapse
Affiliation(s)
- G Spada
- Pitaevskii BEC Center, CNR-INO and Dipartimento di Fisica, Università di Trento, I-38123 Trento, Italy
- School of Science and Technology, Physics Division, Università di Camerino, 62032 Camerino, Italy
- INFN, Sezione di Perugia, I-06123 Perugia, Italy
| | | | | |
Collapse
|
2
|
Liu R, Wang W, Cui X. Quartet Superfluid in Two-Dimensional Mass-Imbalanced Fermi Mixtures. PHYSICAL REVIEW LETTERS 2023; 131:193401. [PMID: 38000427 DOI: 10.1103/physrevlett.131.193401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2023] [Revised: 09/25/2023] [Accepted: 10/19/2023] [Indexed: 11/26/2023]
Abstract
Quartet superfluid (QSF) is a distinct type of fermion superfluidity that exhibits high-order correlation beyond the conventional BCS pairing paradigm. In this Letter, we report the emergent QSF in 2D mass-imbalanced Fermi mixtures with two-body contact interactions. This is facilitated by the formation of a quartet bound state in vacuum that consists of a light atom and three heavy fermions. For an optimized heavy-light number ratio 3:1, we identify QSF as the ground state in a considerable parameter regime of mass imbalance and 2D coupling strength. Its unique high-order correlation can be manifested in the momentum-space crystallization of a pairing field and density distribution of heavy fermions. Our results can be readily detected in Fermi-Fermi mixtures nowadays realized in cold atoms laboratories, and meanwhile shed light on exotic superfluidity in a broad context of mass-imbalanced fermion mixtures.
Collapse
Affiliation(s)
- Ruijin Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Wei Wang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xiaoling Cui
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| |
Collapse
|
3
|
Zhang C, Capogrosso-Sansone B, Boninsegni M, Prokof'ev NV, Svistunov BV. Superconducting Transition Temperature of the Bose One-Component Plasma. PHYSICAL REVIEW LETTERS 2023; 130:236001. [PMID: 37354424 DOI: 10.1103/physrevlett.130.236001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Accepted: 05/24/2023] [Indexed: 06/26/2023]
Abstract
We present results of numerically exact simulations of the Bose one-component plasma, i.e., a Bose gas with pairwise Coulomb interactions among particles and a uniform neutralizing background. We compute the superconducting transition temperature for a wide range of densities, in two and three dimensions, for both continuous and lattice versions of the model. The Coulomb potential causes the weakly interacting limit to be approached at high density, but gives rise to no qualitatively different behavior, vis-à-vis the superfluid transition, with respect to short-ranged interactions. Our results are of direct relevance to quantitative studies of bipolaron mechanisms of (high-temperature) superconductivity.
Collapse
Affiliation(s)
- Chao Zhang
- Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | | | - Massimo Boninsegni
- Department of Physics, University of Alberta, Edmonton, Alberta, Canada T6G 2H5
| | - Nikolay V Prokof'ev
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Boris V Svistunov
- Department of Physics, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Wilczek Quantum Center, School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240, China
| |
Collapse
|
4
|
Zhu Z, Yao H, Sanchez-Palencia L. Thermodynamic Phase Diagram of Two-Dimensional Bosons in a Quasicrystal Potential. PHYSICAL REVIEW LETTERS 2023; 130:220402. [PMID: 37327407 DOI: 10.1103/physrevlett.130.220402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2022] [Accepted: 05/10/2023] [Indexed: 06/18/2023]
Abstract
Quantum simulation of quasicrystals in synthetic bosonic matter now paves the way for the exploration of these intriguing systems in wide parameter ranges. Yet thermal fluctuations in such systems compete with quantum coherence and significantly affect the zero-temperature quantum phases. Here we determine the thermodynamic phase diagram of interacting bosons in a two-dimensional, homogeneous quasicrystal potential. We find our results using quantum Monte Carlo simulations. Finite-size effects are carefully taken into account and the quantum phases are systematically distinguished from thermal phases. In particular, we demonstrate stabilization of a genuine Bose glass phase against the normal fluid in sizable parameter ranges. We interpret our results for strong interactions using a fermionization picture and discuss experimental relevance.
Collapse
Affiliation(s)
- Zhaoxuan Zhu
- CPHT, CNRS, Ecole Polytechnique, IP Paris, F-91128 Palaiseau, France
| | - Hepeng Yao
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, CH-1211 Geneva, Switzerland
| | | |
Collapse
|
5
|
Gałka M, Christodoulou P, Gazo M, Karailiev A, Dogra N, Schmitt J, Hadzibabic Z. Emergence of Isotropy and Dynamic Scaling in 2D Wave Turbulence in a Homogeneous Bose Gas. PHYSICAL REVIEW LETTERS 2022; 129:190402. [PMID: 36399756 DOI: 10.1103/physrevlett.129.190402] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2022] [Revised: 08/24/2022] [Accepted: 09/14/2022] [Indexed: 06/16/2023]
Abstract
We realize a turbulent cascade of wave excitations in a homogeneous 2D Bose gas and probe on all relevant time and length scales how it builds up from small to large momenta, until the system reaches a steady state with matching energy injection and dissipation. This all-scales view directly reveals the two theoretically expected cornerstones of turbulence formation-the emergence of statistical momentum-space isotropy under anisotropic forcing and the spatiotemporal scaling of the momentum distribution at times before any energy is dissipated.
Collapse
Affiliation(s)
- Maciej Gałka
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Panagiotis Christodoulou
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Martin Gazo
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Andrey Karailiev
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Nishant Dogra
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| | - Julian Schmitt
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
- Institut für Angewandte Physik, Universität Bonn, Wegelerstraße 8, 53115 Bonn, Germany
| | - Zoran Hadzibabic
- Cavendish Laboratory, University of Cambridge, J. J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
| |
Collapse
|
6
|
Sunami S, Singh VP, Garrick D, Beregi A, Barker AJ, Luksch K, Bentine E, Mathey L, Foot CJ. Observation of the Berezinskii-Kosterlitz-Thouless Transition in a Two-Dimensional Bose Gas via Matter-Wave Interferometry. PHYSICAL REVIEW LETTERS 2022; 128:250402. [PMID: 35802452 DOI: 10.1103/physrevlett.128.250402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Revised: 12/15/2021] [Accepted: 04/18/2022] [Indexed: 06/15/2023]
Abstract
We probe local phase fluctuations of trapped two-dimensional Bose gases using matter-wave interferometry. This enables us to measure the phase correlation function, which changes from an algebraic to an exponential decay when the system crosses the Berezinskii-Kosterlitz-Thouless (BKT) transition. We determine the temperature dependence of the BKT exponent η and find the critical value η_{c}=0.17(3) for our trapped system. Furthermore, we measure the local vortex density as a function of the local phase-space density, which shows a scale-invariant behavior across the transition. Our experimental investigation is supported by Monte Carlo simulations and provides a comprehensive understanding of the BKT transition in a trapped system.
Collapse
Affiliation(s)
- S Sunami
- Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - V P Singh
- Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstraße 2, 30167 Hannover, Germany
- Zentrum für Optische Quantentechnologien and Institut für Laserphysik, Universität Hamburg, 22761 Hamburg, Germany
| | - D Garrick
- Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - A Beregi
- Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - A J Barker
- Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - K Luksch
- Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - E Bentine
- Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
| | - L Mathey
- Zentrum für Optische Quantentechnologien and Institut für Laserphysik, Universität Hamburg, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, Hamburg 22761, Germany
| | - C J Foot
- Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom
| |
Collapse
|
7
|
Many-body and temperature effects in two-dimensional quantum droplets in Bose-Bose mixtures. Sci Rep 2021; 11:21765. [PMID: 34741072 PMCID: PMC8571397 DOI: 10.1038/s41598-021-01089-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2021] [Accepted: 10/15/2021] [Indexed: 11/25/2022] Open
Abstract
We study the equilibrium properties of self-bound droplets in two-dimensional Bose mixtures employing the time-dependent Hartree–Fock–Bogoliubov theory. This theory allows one to understand both the many-body and temperature effects beyond the Lee–Huang–Yang description. We calculate higher-order corrections to the excitations, the sound velocity, and the energy of the droplet. Our results for the ground-state energy are compared with the diffusion Monte Carlo data and good agreement is found. The behavior of the depletion and anomalous density of the droplet is also discussed. At finite temperature, we show that the droplet emerges at temperatures well below the Berezinskii–Kosterlitz–Thouless transition temperature. The critical temperature strongly depends on the interspecies interactions. Our study is extended to the finite size droplet by numerically solving the generalized finite-temperature Gross-Pitaevskii equation which is obtained self-consistently from our formalism in the framework of the local density approximation.
Collapse
|
8
|
Christodoulou P, Gałka M, Dogra N, Lopes R, Schmitt J, Hadzibabic Z. Observation of first and second sound in a BKT superfluid. Nature 2021; 594:191-194. [PMID: 34108696 DOI: 10.1038/s41586-021-03537-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2020] [Accepted: 04/12/2021] [Indexed: 02/05/2023]
Abstract
Superfluidity in its various forms has been of interest since the observation of frictionless flow in liquid helium II1,2. In three spatial dimensions it is conceptually associated with the emergence of long-range order at a critical temperature. One of the hallmarks of superfluidity, as predicted by the two-fluid model3,4 and observed in both liquid helium5 and in ultracold atomic gases6,7, is the existence of two kinds of sound excitation-the first and second sound. In two-dimensional systems, thermal fluctuations preclude long-range order8,9; however, superfluidity nevertheless emerges at a non-zero critical temperature through the infinite-order Berezinskii-Kosterlitz-Thouless (BKT) transition10,11, which is associated with a universal jump12 in the superfluid density without any discontinuities in the thermodynamic properties of the fluid. BKT superfluids are also predicted to support two sounds, but so far this has not been observed experimentally. Here we observe first and second sound in a homogeneous two-dimensional atomic Bose gas, and use the two temperature-dependent sound speeds to determine the superfluid density of the gas13-16. Our results agree with the predictions of BKT theory, including the prediction of a universal jump in the superfluid density at the critical temperature.
Collapse
Affiliation(s)
| | - Maciej Gałka
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | - Nishant Dogra
- Cavendish Laboratory, University of Cambridge, Cambridge, UK
| | - Raphael Lopes
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL Research University, Sorbonne Université, Paris, France
| | - Julian Schmitt
- Cavendish Laboratory, University of Cambridge, Cambridge, UK.,Institut für Angewandte Physik, Universität Bonn, Bonn, Germany
| | | |
Collapse
|
9
|
Berezinskii-Kosterlitz-Thouless phase induced by dissipating quasisolitons. Sci Rep 2021; 11:10773. [PMID: 34031458 PMCID: PMC8144421 DOI: 10.1038/s41598-021-90169-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2021] [Accepted: 05/05/2021] [Indexed: 11/08/2022] Open
Abstract
We theoretically study the sound propagation in a two-dimensional weakly interacting uniform Bose gas. Using the classical fields approximation we analyze in detail the properties of density waves generated both in a weak and strong perturbation regimes. While in the former case density excitations can be described in terms of hydrodynamic or collisionless sound, the strong disturbance of the system results in a qualitatively different response. We identify observed structures as quasisolitons and uncover their internal complexity for strong perturbation case. For this regime quasisolitons break into vortex pairs as time progresses, eventually reaching an equilibrium state. We find this state, characterized by only fluctuating in time averaged number of pairs of opposite charge vortices and by appearance of a quasi-long-range order, as the Berezinskii-Kosterlitz-Thouless (BKT) phase.
Collapse
|
10
|
Zhang Z, Chen L, Yao KX, Chin C. Transition from an atomic to a molecular Bose-Einstein condensate. Nature 2021; 592:708-711. [PMID: 33911270 DOI: 10.1038/s41586-021-03443-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2020] [Accepted: 03/11/2021] [Indexed: 11/09/2022]
Abstract
Molecular quantum gases (that is, ultracold and dense molecular gases) have many potential applications, including quantum control of chemical reactions, precision measurements, quantum simulation and quantum information processing1-3. For molecules, to reach the quantum regime usually requires efficient cooling at high densities, which is frequently hindered by fast inelastic collisions that heat and deplete the population of molecules4,5. Here we report the preparation of two-dimensional Bose-Einstein condensates (BECs) of spinning molecules by inducing pairing interactions in an atomic condensate near a g-wave Feshbach resonance6. The trap geometry and the low temperature of the molecules help to reduce inelastic loss, ensuring thermal equilibrium. From the equation-of-state measurement, we determine the molecular scattering length to be + 220(±30) Bohr radii (95% confidence interval). We also investigate the unpairing dynamics in the strong coupling regime and find that near the Feshbach resonance the dynamical timescale is consistent with the unitarity limit. Our work demonstrates the long-sought transition between atomic and molecular condensates, the bosonic analogue of the crossover from a BEC to a Bardeen-Cooper-Schrieffer (BCS) superfluid in a Fermi gas7-9. In addition, our experiment may shed light on condensed pairs with orbital angular momentum, where a novel anisotropic superfluid with non-zero surface current is predicted10,11, such as the A phase of 3He.
Collapse
Affiliation(s)
- Zhendong Zhang
- James Franck Institute, Enrico Fermi Institute and Department of Physics, University of Chicago, Chicago, IL, USA
| | - Liangchao Chen
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Opto-Electronics, Shanxi University, Taiyuan, China
| | - Kai-Xuan Yao
- James Franck Institute, Enrico Fermi Institute and Department of Physics, University of Chicago, Chicago, IL, USA
| | - Cheng Chin
- James Franck Institute, Enrico Fermi Institute and Department of Physics, University of Chicago, Chicago, IL, USA.
| |
Collapse
|
11
|
Tan's two-body contact across the superfluid transition of a planar Bose gas. Nat Commun 2021; 12:760. [PMID: 33536418 PMCID: PMC7858573 DOI: 10.1038/s41467-020-20647-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 12/11/2020] [Indexed: 11/11/2022] Open
Abstract
Tan’s contact is a quantity that unifies many different properties of a low-temperature gas with short-range interactions, from its momentum distribution to its spatial two-body correlation function. Here, we use a Ramsey interferometric method to realize experimentally the thermodynamic definition of the two-body contact, i.e., the change of the internal energy in a small modification of the scattering length. Our measurements are performed on a uniform two-dimensional Bose gas of 87Rb atoms across the Berezinskii–Kosterlitz–Thouless superfluid transition. They connect well to the theoretical predictions in the limiting cases of a strongly degenerate fluid and of a normal gas. They also provide the variation of this key quantity in the critical region, where further theoretical efforts are needed to account for our findings. Here the authors use Ramsey interferometry to study Tan’s contact in uniform two-dimensional Bose gas of 87Rb atoms across the Berezinskii–Kosterlitz–Thouless superfluid transition. They find that the two-body contact is continuous across the critical point.
Collapse
|
12
|
Tian C, Zhou B, Xu C, Zhang Y, Zheng X, Zhang J, Zhang L, Dong H, Zhou W. Polariton-Polariton Interactions Revealed in a One-dimensional Whispering Gallery Microcavity. NANO LETTERS 2020; 20:1552-1560. [PMID: 32097561 DOI: 10.1021/acs.nanolett.9b04121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Coulomb interactions are essential to the dynamics and optical properties of exciton-polaritons. Here, we report an experimental observation of polariton-polariton interactions far beyond theory in a one-dimensional whispering gallery microcavity. Based on the unique half-light half-matter nature, we were able to clarify the effects of excitons, quantum confinement, and nonthermalized polariton distribution in the measurements of the polaritonic interactions. Spectacularly, our position-scan and power-scan investigations both revealed that the polariton-polariton interaction strength is up to 2 orders of magnitude larger than theoretical predictions. These results suggest that polaritonic interactions are far more complicated than the expectation and should be re-examined in polariton physics and devices involving polaritonic interactions.
Collapse
Affiliation(s)
- Chuan Tian
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Beier Zhou
- Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai, China
| | - Chunyan Xu
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Yingjun Zhang
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Xiamei Zheng
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Jian Zhang
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Long Zhang
- Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai, China
- Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, No.1, Sub-Lane Xiangshan, Xihu District, 310024 Hangzhou, China
| | - Hongxing Dong
- Key Laboratory of Materials for High-Power Laser, Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Science, Shanghai, China
- Hangzhou Institute for Advanced Study, University of Chinese Academy of Sciences, No.1, Sub-Lane Xiangshan, Xihu District, 310024 Hangzhou, China
| | - Weihang Zhou
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science and Technology, Wuhan 430074, China
| |
Collapse
|
13
|
Guo Y, Dubessy R, de Herve MDG, Kumar A, Badr T, Perrin A, Longchambon L, Perrin H. Supersonic Rotation of a Superfluid: A Long-Lived Dynamical Ring. PHYSICAL REVIEW LETTERS 2020; 124:025301. [PMID: 32004036 DOI: 10.1103/physrevlett.124.025301] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2019] [Indexed: 06/10/2023]
Abstract
We present the experimental realization of a long-lived superfluid flow of a quantum gas rotating in an anharmonic potential, sustained by its own angular momentum. The gas is set into motion by rotating an elliptical deformation of the trap. An evaporation selective in angular momentum yields an acceleration of rotation until the density vanishes at the trap center, resulting in a dynamical ring with ≃350ℏ angular momentum per particle. The density profile of the ring corresponds to the one of a quasi two-dimensional superfluid, with a linear velocity reaching Mach 18 and a rotation lasting more than a minute.
Collapse
Affiliation(s)
- Yanliang Guo
- Laboratoire de physique des lasers, Université Paris 13 Sorbonne Paris Cité, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
- LPL, CNRS UMR 7538, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
| | - Romain Dubessy
- Laboratoire de physique des lasers, Université Paris 13 Sorbonne Paris Cité, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
- LPL, CNRS UMR 7538, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
| | - Mathieu de Goër de Herve
- Laboratoire de physique des lasers, Université Paris 13 Sorbonne Paris Cité, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
- LPL, CNRS UMR 7538, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
| | - Avinash Kumar
- Laboratoire de physique des lasers, Université Paris 13 Sorbonne Paris Cité, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
- LPL, CNRS UMR 7538, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
| | - Thomas Badr
- Laboratoire de physique des lasers, Université Paris 13 Sorbonne Paris Cité, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
- LPL, CNRS UMR 7538, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
| | - Aurélien Perrin
- Laboratoire de physique des lasers, Université Paris 13 Sorbonne Paris Cité, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
- LPL, CNRS UMR 7538, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
| | - Laurent Longchambon
- Laboratoire de physique des lasers, Université Paris 13 Sorbonne Paris Cité, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
- LPL, CNRS UMR 7538, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
| | - Hélène Perrin
- Laboratoire de physique des lasers, Université Paris 13 Sorbonne Paris Cité, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
- LPL, CNRS UMR 7538, 99 avenue J.-B. Clément, F-93430 Villetaneuse, France
| |
Collapse
|
14
|
Tononi A, Salasnich L. Bose-Einstein Condensation on the Surface of a Sphere. PHYSICAL REVIEW LETTERS 2019; 123:160403. [PMID: 31702355 DOI: 10.1103/physrevlett.123.160403] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Indexed: 06/10/2023]
Abstract
Motivated by the recent achievement of space-based Bose-Einstein condensates (BEC) with ultracold alkali-metal atoms under microgravity and by the proposal of bubble traps which confine atoms on a thin shell, we investigate the BEC thermodynamics on the surface of a sphere. We determine analytically the critical temperature and the condensate fraction of a noninteracting Bose gas. Then we consider the inclusion of a zero-range interatomic potential, extending the noninteracting results at zero and finite temperature. Both in the noninteracting and interacting cases the crucial role of the finite radius of the sphere is emphasized, showing that in the limit of infinite radius one recovers the familiar two-dimensional results. We also investigate the Berezinski-Kosterlitz-Thouless transition driven by vortical configurations on the surface of the sphere, analyzing the interplay of condensation and superfluidity in this finite-size system.
Collapse
Affiliation(s)
- A Tononi
- Dipartimento di Fisica e Astronomia "Galileo Galilei", Università di Padova, via Marzolo 8, 35131 Padova, Italy
| | - L Salasnich
- Dipartimento di Fisica e Astronomia "Galileo Galilei", Università di Padova, via Marzolo 8, 35131 Padova, Italy and Istituto Nazionale di Ottica (INO) del Consiglio Nazionale delle Ricerche (CNR), via Nello Carrara 1, 50125 Sesto Fiorentino, Italy
| |
Collapse
|
15
|
Ota M, Larcher F, Dalfovo F, Pitaevskii L, Proukakis NP, Stringari S. Collisionless Sound in a Uniform Two-Dimensional Bose Gas. PHYSICAL REVIEW LETTERS 2018; 121:145302. [PMID: 30339431 DOI: 10.1103/physrevlett.121.145302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Indexed: 06/08/2023]
Abstract
Using linear response theory within the random phase approximation, we investigate the propagation of sound in a uniform two dimensional (2D) Bose gas in the collisionless regime. We show that the sudden removal of a static density perturbation produces a damped oscillatory behavior revealing that sound can propagate also in the absence of collisions, due to mean-field interaction effects. We provide explicit results for the sound velocity and damping as a function of temperature, pointing out the crucial role played by Landau damping. We support our predictions by performing numerical simulations with the stochastic (projected) Gross-Pitaevskii equation. The results are consistent with the recent experimental observation of sound in a weakly interacting 2D Bose gas both below and above the superfluid Berezinskii-Kosterlitz-Thouless transition.
Collapse
Affiliation(s)
- Miki Ota
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Trento, Italy
| | - Fabrizio Larcher
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Trento, Italy
- Joint Quantum Centre Durham-Newcastle, School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - Franco Dalfovo
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Trento, Italy
| | - Lev Pitaevskii
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Trento, Italy
- Kapitza Institute for Physical Problems, Russian Academy of Science, Kosygina 2, 119334 Moscow, Russia
| | - Nick P Proukakis
- Joint Quantum Centre Durham-Newcastle, School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - Sandro Stringari
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Trento, Italy
| |
Collapse
|
16
|
Ville JL, Saint-Jalm R, Le Cerf É, Aidelsburger M, Nascimbène S, Dalibard J, Beugnon J. Sound Propagation in a Uniform Superfluid Two-Dimensional Bose Gas. PHYSICAL REVIEW LETTERS 2018; 121:145301. [PMID: 30339451 DOI: 10.1103/physrevlett.121.145301] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Indexed: 06/08/2023]
Abstract
In superfluid systems several sound modes can be excited, such as, for example, first and second sound in liquid helium. Here, we excite running and standing waves in a uniform two-dimensional Bose gas and we characterize the propagation of sound in both the superfluid and normal regimes. In the superfluid phase, the measured speed of sound is in good agreement with the prediction of a two-fluid hydrodynamic model, and the weak damping is well explained by the scattering with thermal excitations. In the normal phase we observe a stronger damping, which we attribute to a departure from hydrodynamic behavior.
Collapse
Affiliation(s)
- J L Ville
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - R Saint-Jalm
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - É Le Cerf
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - M Aidelsburger
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - S Nascimbène
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - J Dalibard
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - J Beugnon
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| |
Collapse
|
17
|
Bertoli G, Michal VP, Altshuler BL, Shlyapnikov GV. Finite-Temperature Disordered Bosons in Two Dimensions. PHYSICAL REVIEW LETTERS 2018; 121:030403. [PMID: 30085818 DOI: 10.1103/physrevlett.121.030403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/25/2017] [Indexed: 06/08/2023]
Abstract
We study phase transitions in a two dimensional weakly interacting Bose gas in a random potential at finite temperatures. We identify superfluid, normal fluid, and insulator phases and construct the phase diagram. At T=0 one has a tricritical point where the three phases coexist. The truncation of the energy distribution at the trap barrier, which is a generic phenomenon in cold atom systems, limits the growth of the localization length and in contrast to the thermodynamic limit the insulator phase is present at any temperature.
Collapse
Affiliation(s)
- G Bertoli
- LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Orsay 91405, France
| | - V P Michal
- QuTech and Kavli Institute of Nanoscience, TU Delft, 2600 GA Delft, Netherlands
| | - B L Altshuler
- Physics Department, Columbia University, 538 West 120th Street, New York, New York 10027, USA
| | - G V Shlyapnikov
- LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Orsay 91405, France
- SPEC, CEA, CNRS, Université Paris-Saclay, CEA Saclay, Gif sur Yvette 91191, France
- Russian Quantum Center, Skolkovo, Moscow Region 143025, Russia
- Van der Waals-Zeeman Institute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, Netherlands
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| |
Collapse
|
18
|
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.
Collapse
|
19
|
Boettcher I, Bayha L, Kedar D, Murthy PA, Neidig M, Ries MG, Wenz AN, Zürn G, Jochim S, Enss T. Equation of State of Ultracold Fermions in the 2D BEC-BCS Crossover Region. PHYSICAL REVIEW LETTERS 2016; 116:045303. [PMID: 26871341 DOI: 10.1103/physrevlett.116.045303] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Indexed: 06/05/2023]
Abstract
We report the experimental measurement of the equation of state of a two-dimensional Fermi gas with attractive s-wave interactions throughout the crossover from a weakly coupled Fermi gas to a Bose gas of tightly bound dimers as the interaction strength is varied. We demonstrate that interactions lead to a renormalization of the density of the Fermi gas by several orders of magnitude. We compare our data near the ground state and at finite temperature with predictions for both fermions and bosons from quantum Monte Carlo simulations and Luttinger-Ward theory. Our results serve as input for investigations of close-to-equilibrium dynamics and transport in the two-dimensional system.
Collapse
Affiliation(s)
- I Boettcher
- Institute for Theoretical Physics, Heidelberg University, D-69120 Heidelberg, Germany
| | - L Bayha
- Physikalisches Institut, Heidelberg University, D-69120 Heidelberg, Germany
| | - D Kedar
- Physikalisches Institut, Heidelberg University, D-69120 Heidelberg, Germany
| | - P A Murthy
- Physikalisches Institut, Heidelberg University, D-69120 Heidelberg, Germany
| | - M Neidig
- Physikalisches Institut, Heidelberg University, D-69120 Heidelberg, Germany
| | - M G Ries
- Physikalisches Institut, Heidelberg University, D-69120 Heidelberg, Germany
| | - A N Wenz
- Physikalisches Institut, Heidelberg University, D-69120 Heidelberg, Germany
| | - G Zürn
- Physikalisches Institut, Heidelberg University, D-69120 Heidelberg, Germany
| | - S Jochim
- Physikalisches Institut, Heidelberg University, D-69120 Heidelberg, Germany
| | - T Enss
- Institute for Theoretical Physics, Heidelberg University, D-69120 Heidelberg, Germany
| |
Collapse
|
20
|
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]
|
21
|
Murthy PA, Boettcher I, Bayha L, Holzmann M, Kedar D, Neidig M, Ries MG, Wenz AN, Zürn G, Jochim S. Observation of the Berezinskii-Kosterlitz-Thouless Phase Transition in an Ultracold Fermi Gas. PHYSICAL REVIEW LETTERS 2015; 115:010401. [PMID: 26182082 DOI: 10.1103/physrevlett.115.010401] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Indexed: 06/04/2023]
Abstract
We experimentally investigate the first-order correlation function of a trapped Fermi gas in the two-dimensional BEC-BCS crossover. We observe a transition to a low-temperature superfluid phase with algebraically decaying correlations. We show that the spatial coherence of the entire trapped system can be characterized by a single temperature-dependent exponent. We find the exponent at the transition to be constant over a wide range of interaction strengths across the crossover. This suggests that the phase transitions in both the bosonic regime and the strongly interacting crossover regime are of Berezinskii-Kosterlitz-Thouless type and lie within the same universality class. On the bosonic side of the crossover, our data are well described by the quantum Monte Carlo calculations for a Bose gas. In contrast, in the strongly interacting regime, we observe a superfluid phase which is significantly influenced by the fermionic nature of the constituent particles.
Collapse
Affiliation(s)
- P A Murthy
- Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, 69120 Heidelberg, Germany
| | - I Boettcher
- Institut für Theoretische Physik, Ruprecht-Karls-Universität Heidelberg, 69120 Heidelberg, Germany
| | - L Bayha
- Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, 69120 Heidelberg, Germany
| | - M Holzmann
- LPTMC, UMR 7600 of CNRS, Université Pierre et Marie Curie, F-75252 Paris Cedex 05, France
- Université Grenoble Alpes, CNRS, LPMMC, UMR 5493, F-38042 Grenoble, France
| | - D Kedar
- Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, 69120 Heidelberg, Germany
| | - M Neidig
- Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, 69120 Heidelberg, Germany
| | - M G Ries
- Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, 69120 Heidelberg, Germany
| | - A N Wenz
- Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, 69120 Heidelberg, Germany
| | - G Zürn
- Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, 69120 Heidelberg, Germany
| | - S Jochim
- Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, 69120 Heidelberg, Germany
| |
Collapse
|
22
|
Jakubczyk P, Dupuis N, Delamotte B. Reexamination of the nonperturbative renormalization-group approach to the Kosterlitz-Thouless transition. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2014; 90:062105. [PMID: 25615042 DOI: 10.1103/physreve.90.062105] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2014] [Indexed: 06/04/2023]
Abstract
We reexamine the two-dimensional linear O(2) model (φ4 theory) in the framework of the nonperturbative renormalization-group. From the flow equations obtained in the derivative expansion to second order and with optimization of the infrared regulator, we find a transition between a high-temperature (disordered) phase and a low-temperature phase displaying a line of fixed points and algebraic order. We obtain a picture in agreement with the standard theory of the Kosterlitz-Thouless (KT) transition and reproduce the universal features of the transition. In particular, we find the anomalous dimension η(T(KT))≃0.24 and the stiffness jump ρ(s)(T(KT)(-))≃0.64 at the transition temperature T(KT), in very good agreement with the exact results η(T(KT))=1/4 and ρ(s)(T(KT)(-))=2/π, as well as an essential singularity of the correlation length in the high-temperature phase as T→T(KT).
Collapse
Affiliation(s)
- P Jakubczyk
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - N Dupuis
- Laboratoire de Physique Théorique de la Matière Condensée, CNRS UMR 7600, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France
| | - B Delamotte
- Laboratoire de Physique Théorique de la Matière Condensée, CNRS UMR 7600, Université Pierre et Marie Curie, 4 Place Jussieu, 75252 Paris Cedex 05, France
| |
Collapse
|
23
|
Radić J, Natu SS, Galitski V. Stoner ferromagnetism in a thermal pseudospin-1/2 Bose gas. PHYSICAL REVIEW LETTERS 2014; 113:185302. [PMID: 25396377 DOI: 10.1103/physrevlett.113.185302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Indexed: 06/04/2023]
Abstract
We compute the finite-temperature phase diagram of a pseudospin-1/2 Bose gas with contact interactions, using two complementary methods: the random-phase approximation and self-consistent Hartree-Fock theory. We show that the spin-dependent interactions, which break the (pseudo-) spin-rotational symmetry of the Hamiltonian, generally lead to the appearance of a magnetically ordered phase at temperatures above the superfluid transition. In three dimensions, we predict a normal easy-axis (easy-plane) ferromagnet for sufficiently strong repulsive (attractive) interspecies interactions, respectively. The normal easy-axis ferromagnet is the bosonic analog of Stoner ferromagnetism known in electronic systems. For the case of interspecies attraction, we also discuss the possibility of a bosonic analog of the Cooper-paired phase. This state is shown to significantly lose in energy to the transverse ferromagnet in three dimensions, but is more energetically competitive in lower dimensions. Extending our calculations to a spin-orbit-coupled Bose gas with equal Rashba and Dresselhaus-type couplings (as recently realized in experiment), we investigate the possibility of stripe ordering in the normal phase. Within our approximations, however, we do not find an instability towards stripe formation, suggesting that the stripe order melts below the condensation temperature, which is consistent with the experimental observations of Ji et al. [Ji et al., Nat. Phys. 10, 314 (2014)].
Collapse
Affiliation(s)
- Juraj Radić
- Joint Quantum Institute and Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA
| | - Stefan S Natu
- Joint Quantum Institute and Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA
| | - Victor Galitski
- Joint Quantum Institute and Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA and School of Physics, Monash University, Melbourne, Victoria 3800, Australia
| |
Collapse
|
24
|
Desbuquois R, Yefsah T, Chomaz L, Weitenberg C, Corman L, Nascimbène S, Dalibard J. Determination of scale-invariant equations of state without fitting parameters: application to the two-dimensional Bose gas across the Berezinskii-Kosterlitz-Thouless transition. PHYSICAL REVIEW LETTERS 2014; 113:020404. [PMID: 25062145 DOI: 10.1103/physrevlett.113.020404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Indexed: 06/03/2023]
Abstract
We present a general "fit-free" method for measuring the equation of state (EoS) of a scale-invariant gas. This method, which is inspired from the procedure introduced by Ku et al. [Science 335, 563 (2012)] for the unitary three-dimensional Fermi gas, provides a general formalism which can be readily applied to any quantum gas in a known trapping potential, in the frame of the local density approximation. We implement this method on a weakly interacting two-dimensional Bose gas across the Berezinskii-Kosterlitz-Thouless transition and determine its EoS with unprecedented accuracy in the critical region. Our measurements provide an important experimental benchmark for classical-field approaches which are believed to accurately describe quantum systems in the weakly interacting but nonperturbative regime.
Collapse
Affiliation(s)
- Rémi Desbuquois
- Institute for Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland
| | - Tarik Yefsah
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Lauriane Chomaz
- Laboratoire Kastler Brossel, CNRS, UPMC, ENS, 24 rue Lhomond, F-75005 Paris, France and Collège de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France
| | - Christof Weitenberg
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, D-22761 Hamburg, Germany
| | - Laura Corman
- Laboratoire Kastler Brossel, CNRS, UPMC, ENS, 24 rue Lhomond, F-75005 Paris, France
| | - Sylvain Nascimbène
- Laboratoire Kastler Brossel, CNRS, UPMC, ENS, 24 rue Lhomond, F-75005 Paris, France
| | - Jean Dalibard
- Laboratoire Kastler Brossel, CNRS, UPMC, ENS, 24 rue Lhomond, F-75005 Paris, France and Collège de France, 11 Place Marcelin Berthelot, 75231 Paris Cedex 05, France
| |
Collapse
|
25
|
Makhalov V, Martiyanov K, Turlapov A. Ground-state pressure of quasi-2D Fermi and Bose gases. PHYSICAL REVIEW LETTERS 2014; 112:045301. [PMID: 24580463 DOI: 10.1103/physrevlett.112.045301] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Indexed: 06/03/2023]
Abstract
Using an ultracold gas of atoms, we have realized a quasi-two-dimensional Fermi system with widely tunable s-wave interactions nearly in a ground state. Pressure and density are measured. The experiment covers physically different regimes: weakly and strongly attractive Fermi gases and a Bose gas of tightly bound pairs of fermions. In the Fermi regime of weak interactions, the pressure is systematically above a Fermi-liquid-theory prediction, maybe due to mesoscopic effects. In the opposite Bose regime, the pressure agrees with a bosonic mean-field scaling in a range beyond simplest expectations. In the strongly interacting regime, measurements disagree with a purely 2D model. Reported data may serve for sensitive testing of theoretical methods applicable across different quantum physics disciplines.
Collapse
Affiliation(s)
- Vasiliy Makhalov
- Institute of Applied Physics, Russian Academy of Sciences, ulitsa Ulyanova 46, Nizhniy Novgorod, 603000, Russia
| | - Kirill Martiyanov
- Institute of Applied Physics, Russian Academy of Sciences, ulitsa Ulyanova 46, Nizhniy Novgorod, 603000, Russia
| | - Andrey Turlapov
- Institute of Applied Physics, Russian Academy of Sciences, ulitsa Ulyanova 46, Nizhniy Novgorod, 603000, Russia
| |
Collapse
|
26
|
Ozawa T, Stringari S. Discontinuities in the first and second sound velocities at the Berezinskii-Kosterlitz-Thouless transition. PHYSICAL REVIEW LETTERS 2014; 112:025302. [PMID: 24484023 DOI: 10.1103/physrevlett.112.025302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/14/2013] [Indexed: 06/03/2023]
Abstract
We calculate the temperature dependence of the first and second sound velocities in the superfluid phase of a 2D dilute Bose gas by solving Landau's two fluid hydrodynamic equations. We predict the occurrence of a significant discontinuity in both velocities at the critical temperature, as a consequence of the jump of the superfluid density characterizing the Berezinskii-Kosterlitz-Thouless transition. The key role of the thermal expansion coefficient is discussed. We find that second sound in this dilute Bose gas can be easily excited through a density perturbation, thereby, making the perspective of the measurement of the superfluid density particularly favorable.
Collapse
Affiliation(s)
- Tomoki Ozawa
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, I-38123 Povo, Italy
| | - Sandro Stringari
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, I-38123 Povo, Italy
| |
Collapse
|
27
|
Carleo G, Boéris G, Holzmann M, Sanchez-Palencia L. Universal superfluid transition and transport properties of two-dimensional dirty bosons. PHYSICAL REVIEW LETTERS 2013; 111:050406. [PMID: 23952374 DOI: 10.1103/physrevlett.111.050406] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Indexed: 06/02/2023]
Abstract
We study the phase diagram of two-dimensional, interacting bosons in the presence of a correlated disorder in continuous space, by using large-scale quantum Monte Carlo simulations at finite temperature. We show that the superfluid transition is strongly protected against disorder. It remains of the Berezinskii-Kosterlitz-Thouless type up to disorder strengths comparable to the chemical potential. Moreover, we study the transport properties in the strong disorder regime where a zero-temperature Bose-glass phase is expected. We show that the conductance exhibits a thermally activated behavior vanishing only at zero temperature. Our results point towards the existence of a Bose bad-metal phase as a precursor of the Bose-glass phase.
Collapse
Affiliation(s)
- Giuseppe Carleo
- Laboratoire Charles Fabry, Institut d'Optique, CNRS, Univ Paris Sud 11, 2 avenue Augustin Fresnel, F-91127 Palaiseau cedex, France
| | | | | | | |
Collapse
|
28
|
Rançon A, Kodio O, Dupuis N, Lecheminant P. Thermodynamics in the vicinity of a relativistic quantum critical point in 2+1 dimensions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2013; 88:012113. [PMID: 23944420 DOI: 10.1103/physreve.88.012113] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2013] [Indexed: 06/02/2023]
Abstract
We study the thermodynamics of the relativistic quantum O(N) model in two space dimensions. In the vicinity of the zero-temperature quantum critical point (QCP), the pressure can be written in the scaling form P(T)=P(0)+N(T(3)/c(2))F(N)(Δ/T), where c is the velocity of the excitations at the QCP and |Δ| a characteristic zero-temperature energy scale. Using both a large-N approach to leading order and the nonperturbative renormalization group, we compute the universal scaling function F(N). For small values of N (N</~10) we find that F(N)(x) is nonmonotonic in the quantum critical regime (|x|</~1) with a maximum near x=0. The large-N approach-if properly interpreted-is a good approximation both in the renormalized classical (x</~-1) and quantum disordered (x>/~1) regimes, but fails to describe the nonmonotonic behavior of F(N) in the quantum critical regime. We discuss the renormalization-group flows in the various regimes near the QCP and make the connection with the quantum nonlinear sigma model in the renormalized classical regime. We compute the Berezinskii-Kosterlitz-Thouless transition temperature in the quantum O(2) model and find that in the vicinity of the QCP the universal ratio T(BKT)/ρ(s)(0) is very close to π/2, implying that the stiffness ρ(s)(T(BKT)(-)) at the transition is only slightly reduced with respect to the zero-temperature stiffness ρ(s)(0). Finally, we briefly discuss the experimental determination of the universal function F(2) from the pressure of a Bose gas in an optical lattice near the superfluid-Mott-insulator transition.
Collapse
Affiliation(s)
- A Rançon
- James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | | | | | | |
Collapse
|
29
|
Bisset RN, Blakie PB. Fingerprinting rotons in a dipolar condensate: super-Poissonian peak in the atom-number fluctuations. PHYSICAL REVIEW LETTERS 2013; 110:265302. [PMID: 23848891 DOI: 10.1103/physrevlett.110.265302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2013] [Indexed: 06/02/2023]
Abstract
We demonstrate that measurements of atom-number fluctuations in a trapped dipolar condensate can reveal the presence of the elusive roton excitation. The key signature is a super-Poissonian peak in the fluctuations as the size of the measurement cell is varied, with the maximum occurring when the size is comparable to the roton wavelength. The magnitude of this roton feature is enhanced with temperature. The variation in fluctuations across the condensate demonstrates that the roton excitations are effectively confined to propagate in the densest central region, realizing a density trapped roton gas. While our main results are based on full numerical solutions of the mean-field equations, we also develop and validate a simple local density theory. Finally, we consider fluctuations measured within a washer-shaped cell which filters out the contribution of modes with nonzero angular momentum and provides a signal sensitive to individual roton modes.
Collapse
Affiliation(s)
- R N Bisset
- Department of Physics, Jack Dodd Centre for Quantum Technology, University of Otago, Dunedin 9016, New Zealand
| | | |
Collapse
|
30
|
Ha LC, Hung CL, Zhang X, Eismann U, Tung SK, Chin C. Strongly interacting two-dimensional Bose gases. PHYSICAL REVIEW LETTERS 2013; 110:145302. [PMID: 25167003 DOI: 10.1103/physrevlett.110.145302] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2012] [Indexed: 06/03/2023]
Abstract
We prepare and study strongly interacting two-dimensional Bose gases in the superfluid, the classical Berezinskii-Kosterlitz-Thouless (BKT) transition, and the vacuum-to-superfluid quantum critical regimes. A wide range of the two-body interaction strength 0.05 < g < 3 is covered by tuning the scattering length and by loading the sample into an optical lattice. Based on the equations of state measurements, we extract the coupling constants as well as critical thermodynamic quantities in different regimes. In the superfluid and the BKT transition regimes, the extracted coupling constants show significant down-shifts from the mean-field and perturbation calculations when g approaches or exceeds one. In the BKT and the quantum critical regimes, all measured thermodynamic quantities show logarithmic dependence on the interaction strength, a tendency confirmed by the extended classical-field and renormalization calculations.
Collapse
Affiliation(s)
- Li-Chung Ha
- The James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Chen-Lung Hung
- The James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Xibo Zhang
- The James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Ulrich Eismann
- The James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois 60637, USA and Laboratoire Kastler Brossel, ENS, UPMC, CNRS UMR 8552, 24 rue Lhomond, 75231 Paris, France
| | - Shih-Kuang Tung
- The James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Cheng Chin
- The James Franck Institute and Department of Physics, University of Chicago, Chicago, Illinois 60637, USA and The Enrico Fermi Institute, University of Chicago, Chicago, Illinois 60637, USA
| |
Collapse
|
31
|
Yefsah T, Desbuquois R, Chomaz L, Günter KJ, Dalibard J. Exploring the thermodynamics of a two-dimensional Bose gas. PHYSICAL REVIEW LETTERS 2011; 107:130401. [PMID: 22026829 DOI: 10.1103/physrevlett.107.130401] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/30/2011] [Revised: 07/11/2011] [Indexed: 05/31/2023]
Abstract
Using in situ measurements on a quasi-two-dimensional, harmonically trapped (87)Rb gas, we infer various equations of state for the equivalent homogeneous fluid. From the dependence of the total atom number and the central density of our clouds with chemical potential and temperature, we obtain the equations of state for the pressure and the phase-space density. Then, using the approximate scale invariance of this 2D system, we determine the entropy per particle and find very low values (below 0.1k(B)) in the strongly degenerate regime. This shows that this gas can constitute an efficient coolant for other quantum fluids. We also explain how to disentangle the various contributions (kinetic, potential, interaction) to the energy of the trapped gas using a time-of-flight method, from which we infer the reduction of density fluctuations in a nonfully coherent cloud.
Collapse
Affiliation(s)
- Tarik Yefsah
- Laboratoire Kastler Brossel, CNRS, UPMC, Ecole Normale Supérieure, Paris, France
| | | | | | | | | |
Collapse
|
32
|
Sinatra A, Witkowska E, Dornstetter JC, Li Y, Castin Y. Limit of spin squeezing in finite-temperature Bose-Einstein condensates. PHYSICAL REVIEW LETTERS 2011; 107:060404. [PMID: 21902302 DOI: 10.1103/physrevlett.107.060404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/09/2011] [Revised: 06/29/2011] [Indexed: 05/31/2023]
Abstract
We show that, at finite temperature, the maximum spin squeezing achievable using interactions in Bose-Einstein condensates has a finite limit when the atom number N→∞ at fixed density and interaction strength. We calculate the limit of the squeezing parameter for a spatially homogeneous system and show that it is bounded from above by the initial noncondensed fraction.
Collapse
Affiliation(s)
- A Sinatra
- Laboratoire Kastler Brossel, Ecole Normale Supérieure, UPMC and CNRS, Paris, France
| | | | | | | | | |
Collapse
|
33
|
Observation of scale invariance and universality in two-dimensional Bose gases. Nature 2011; 470:236-9. [PMID: 21270797 DOI: 10.1038/nature09722] [Citation(s) in RCA: 200] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2010] [Accepted: 12/01/2010] [Indexed: 11/09/2022]
Abstract
The collective behaviour of a many-body system near a continuous phase transition is insensitive to the details of its microscopic physics; for example, thermodynamic observables follow generalized scaling laws near the phase transition. The Berezinskii-Kosterlitz-Thouless (BKT) phase transition in two-dimensional Bose gases presents a particularly interesting case because the marginal dimensionality and intrinsic scaling symmetry result in a broad fluctuation regime and an extended range of universal scaling behaviour. Studies of the BKT transition in cold atoms have stimulated great interest in recent years, but a clear demonstration of critical behaviour near the phase transition has remained elusive. Here we report in situ density and density-fluctuation measurements of two-dimensional Bose gases of caesium at different temperatures and interaction strengths, observing scale-invariant, universal behaviours. The extracted thermodynamic functions confirm the existence of a wide universal region near the BKT phase transition, and provide a sensitive test of the universality predicted by classical-field theory and quantum Monte Carlo calculations. Our experimental results provide evidence for growing density-density correlations in the fluctuation region, and call for further explorations of universal phenomena in classical and quantum critical physics.
Collapse
|
34
|
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.
Collapse
Affiliation(s)
- S Tung
- JILA, National Institute of Standards and Technology and University of Colorado, Boulder, Colorado 80309-0440, USA
| | | | | | | | | |
Collapse
|
35
|
Pikovski A, Klawunn M, Shlyapnikov GV, Santos L. Interlayer superfluidity in bilayer systems of fermionic polar molecules. PHYSICAL REVIEW LETTERS 2010; 105:215302. [PMID: 21231317 DOI: 10.1103/physrevlett.105.215302] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 10/12/2010] [Indexed: 05/30/2023]
Abstract
We consider fermionic polar molecules in a bilayer geometry where they are oriented perpendicularly to the layers, which permits both low inelastic losses and superfluid pairing. The dipole-dipole interaction between molecules of different layers leads to the emergence of interlayer superfluids. The superfluid regimes range from BCS-like fermionic superfluidity with a high Tc to Bose-Einstein (quasi-)condensation of interlayer dimers, thus exhibiting a peculiar BCS-Bose-Einstein condensation crossover. We show that one can cover the entire crossover regime under current experimental conditions.
Collapse
Affiliation(s)
- A Pikovski
- Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstrasse 2, 30169, Hannover, Germany
| | | | | | | |
Collapse
|
36
|
Filinov A, Prokof'ev NV, Bonitz M. Berezinskii-Kosterlitz-Thouless transition in two-dimensional dipole systems. PHYSICAL REVIEW LETTERS 2010; 105:070401. [PMID: 20868021 DOI: 10.1103/physrevlett.105.070401] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2010] [Revised: 06/14/2010] [Indexed: 05/29/2023]
Abstract
The superfluid to normal fluid transition of dipolar bosons in two dimensions is studied in a broad density range by using path integral Monte Carlo simulations and summarized in the phase diagram. While at low densities we find good agreement with the universal results depending only on the scattering length a{s}, at moderate and high densities the transition temperature is strongly affected by interactions and the excitation spectrum of quasiparticles. The results are expected to be of relevance to dipolar atomic and molecular systems and indirect excitons in quantum wells.
Collapse
Affiliation(s)
- A Filinov
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität, Leibnizstrasse 15, D-24098 Kiel, Germany
| | | | | |
Collapse
|
37
|
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.
Collapse
Affiliation(s)
- P Cladé
- Atomic Physics Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-8424, USA
| | | | | | | | | |
Collapse
|
38
|
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.
Collapse
|
39
|
Pilati S, Giorgini S, Prokof'ev N. Critical temperature of interacting Bose gases in two and three dimensions. PHYSICAL REVIEW LETTERS 2008; 100:140405. [PMID: 18518010 DOI: 10.1103/physrevlett.100.140405] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/22/2008] [Indexed: 05/26/2023]
Abstract
We calculate the superfluid transition temperature of homogeneous interacting Bose gases in three and two spatial dimensions using large-scale path integral Monte Carlo simulations (with up to N=10;{5} particles). In 3D we investigate the limits of the universal critical behavior in terms of the scattering length alone by using different models for the interatomic potential. We find that this type of universality sets in at small values of the gas parameter na3 < or approximately 10(-4). This value is different from the estimate na3 < or approximately 10(-6) for the validity of the asymptotic expansion in the limit of vanishing na3. In 2D we study the Berezinskii-Kosterlitz-Thouless transition of a gas with hard-core interactions. For this system we find good agreement with the classical lattice |psi|4 model up to very large densities. We also explain the origin of the existing discrepancy between previous studies of the same problem.
Collapse
Affiliation(s)
- S Pilati
- Dipartimento di Fisica, Università di Trento and CNR-INFM BEC Center, I-38050 Povo, Trento, Italy
| | | | | |
Collapse
|
40
|
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.
Collapse
Affiliation(s)
- Peter Krüger
- Laboratoire Kastler Brossel and CNRS, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France
| | | | | |
Collapse
|
41
|
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.
Collapse
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
| |
Collapse
|
42
|
|
43
|
Simula TP, Blakie PB. Thermal activation of vortex-antivortex pairs in quasi-two-dimensional Bose-Einstein condensates. PHYSICAL REVIEW LETTERS 2006; 96:020404. [PMID: 16486547 DOI: 10.1103/physrevlett.96.020404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2005] [Indexed: 05/06/2023]
Abstract
Here we show, by performing ab initio classical field simulations that two distinct superfluid phases, separated by thermal vortex-antivortex pair creation, exist in experimentally producible quasi-2D Bose gas. These results resolve the debate on the nature of the low temperature phase(s) of a trapped interacting 2D Bose gas.
Collapse
Affiliation(s)
- T P Simula
- Department of Physics, University of Otago, P.O. Box 56, Dunedin, New Zealand
| | | |
Collapse
|