Observation of the Berezinskii-Kosterlitz-Thouless transition in a two-dimensional Bose gas via matter-wave interferometry

Journal article

We probe local phase fluctuations of trapped two-dimensional (2D) 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 ηc = 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 behaviour 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.

Authors: Sunami, S; Singh, VP; Garrick, D; Beregi, A; Barker, AJ

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: American Physical Society
• Journal: Physical Review Letters
• Volume: 128
• Issue: 25
• Article number: 250402
• Publication date: 2022-06-22
• Acceptance date: 2022-04-18
• DOI: 10.1103/physrevlett.128.250402
• EISSN: 1079-7114
• ISSN: 0031-9007
• Language: English
• Keywords: FFR