Observation of scale invariance and universality in two-dimensional Bose gases

Abstract

The collective behavior of a many-body system near a continuous phase transition is insensitive to the details of its microscopic physics[1]. Characteristic features near the phase transition are that the thermodynamic observables follow generalized scaling laws[1]. The Berezinskii-Kosterlitz-Thouless (BKT) phase transition[2,3] in two-dimensional (2D) Bose gases presents a particularly interesting case because the marginal dimensionality and intrinsic scaling symmetry[4] result in a broad fluctuation regime which manifests itself in an extended range of universal scaling behavior. Studies on BKT transition in cold atoms have stimulated great interest in recent years[5-10], clear demonstration of a critical behavior near the phase transition, however, has remained an elusive goal. Here we report the observation of a scale-invariant, universal behavior of 2D gases through in-situ density and density fluctuation measurements at different temperatures and interaction strengths. The extracted thermodynamic functions confirm a wide universal region near the BKT phase transition, provide a sensitive test to the universality prediction by classical-field theory[11,12] and quantum Monte Carlo (MC) calculations[13], and point toward growing density-density correlations in the fluctuation region. Our assay raises new perspectives to explore further universal phenomena in the realm of classical and quantum critical physics.

6 pages, 4 figures, to appear in Nature

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• Critical Behavior of a Trapped Interacting Bose Gas
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• Kosterlitz-Thouless transition of the quasi two-dimensional trapped Bose gas
• Superfluidity of an interacting trapped quasi-2D Bose gas

Cited by in corpus (39)

• Quantum Simulation of Antiferromagnetic Spin Chains in an Optical Lattice
• Emergence of coherence in a uniform quasi-two-dimensional Bose gas
• Superfluid behaviour of a two-dimensional Bose gas
• Observation of the Berezinskii-Kosterlitz-Thouless Phase Transition in an Ultracold Fermi Gas
• Observation of pair condensation in the quasi-2D BEC-BCS crossover
• Strongly Interacting Two-Dimensional Bose Gases
• Apparent low-energy scale invariance in two-dimensional Fermi gases
• Connecting Berezinskii-Kosterlitz-Thouless and BEC phase transitions by tuning interactions in a trapped gas
• A two-dimensional quantum gas in a magnetic trap
• Universal thermodynamics of a two-dimensional Bose gas
• Two-body momentum correlations in a weakly interacting one-dimensional Bose gas
• Finite temperature analysis of a quasi2D dipolar gas
• Superfluid to normal phase transition in strongly correlated bosons in two and three dimensions
• Probing Phase Fluctuations in a 2D Degenerate Bose Gas by Free Expansion
• Quantum Criticality from in-situ Density Imaging
• Exploring quantum criticality based on ultracold atoms in optical lattices
• Renormalization-group flow and asymptotic behaviors at the Berezinskii-Kosterlitz-Thouless transitions
• Dispersion relation and excitation character of a two-component Bose-Einstein condensate
• Thermodynamics of a Bose gas near the superfluid--Mott-insulator transition
• Thermal Phase transitions in attractive extended Bose-Hubbard Model with three-body constraint
• Two-dimensional Bose gases near resonance: universal three-body effects
• Isothermal compressibility determination across Bose-Einstein condensation
• Critical phenomena in one dimension from a Bethe ansatz perspective
• Magnetostriction and exchange effects in trapped dipolar Bose and Fermi gases
• Dimensional Effects on the Momentum distribution of Bosonic Trimer States
• Anisotropic Coherence properties in a trapped quasi2D dipolar gas
• Number Fluctuations of a Dipolar Condensate: Anisotropy and Slow Approach to the Thermodynamic Regime
• Coupled Ferromagnetic and Nematic Ordering of Fermions in an Optical Flux Lattice
• Thermally activated local collapse of a flattened dipolar condensate
• Dimensional crossover of Bose-Einstein condensation phenomena in quantum gases confined within slab geometries
• Exotic pairing in 1D spin-3/2 atomic gases with $SO(4)$ symmetry
• Scaling of Fluctuations in a Trapped Binary Condensate
• A model study on a pair of trapped particles interacting with an arbitrary effective range
• Fluctuations of spinor Bose-Einstein condensates
• Creating fractional quantum Hall states with atomic clusters using light-assisted insertion of angular momentum
• First and second sound in a two-dimensional dilute Bose gas across the Berezinskii-Kosterlitz-Thouless transition
• Thermodynamics and renormalized quasi-particles in the vicinity of the dilute Bose gas quantum critical point in two dimensions
• Phase correlations and quasicondensate in a two-dimensional ultracold Fermi gas
• Two- and three- dimensional few-body systems in the universal regime