Sunami S, Singh V P, Garrick D, Beregi A, Barker A J, Luksch K, Bentine E, Mathey L, Foot C J
Clarendon Laboratory, University of Oxford, Oxford OX1 3PU, United Kingdom.
Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstraße 2, 30167 Hannover, Germany.
Phys Rev Lett. 2022 Jun 24;128(25):250402. doi: 10.1103/PhysRevLett.128.250402.
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.
我们利用物质波干涉测量法探测捕获的二维玻色气体的局部相位涨落。这使我们能够测量相位相关函数，当系统越过贝雷津斯基 - 科斯特利茨 - Thouless（BKT）转变时，该函数从代数衰减变为指数衰减。我们确定了BKT指数η的温度依赖性，并为我们的捕获系统找到了临界值η_{c}=0.17(3)。此外，我们测量了局部涡旋密度作为局部相空间密度的函数，其在转变过程中表现出尺度不变行为。我们的实验研究得到了蒙特卡罗模拟的支持，并对捕获系统中的BKT转变提供了全面的理解。
