We observe the proliferation of vortices in the Berezinskii-Kosterlitz-Thouless regime on a two-dimensional array of Josephson-coupled Bose-Einstein condensates. As long as the Josephson (tunneling) energy J exceeds the thermal energy T, the array is vortex-free. With decreasing J/T, vortices appear in the system in ever greater numbers. We confirm thermal activation as the vortex formation mechanism and obtain information on the size of bound vortex pairs as J/T is varied.

我们观察到了漩涡的扩散 二维阵列上的Berezinskii-Kosterlitz-Thouless区域 约瑟夫森耦合的玻色-爱因斯坦凝聚体。只要约瑟夫森号 (隧穿)能量J超过热能T，阵列是无涡流的。 随着J/T的减小，涡旋在系统中出现的数量越来越多。我们 确认热激活为涡旋形成机制，并获得 关于J/T时束缚涡对大小的信息是不同的。