Dipartimento di Fisica e Astronomia "Galileo Galilei", Università di Padova, via Marzolo 8, 35131 Padova, Italy.
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.
Phys Rev Lett. 2019 Oct 18;123(16):160403. doi: 10.1103/PhysRevLett.123.160403.
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.
受近期在微重力下利用超冷碱金属原子实现基于太空的玻色-爱因斯坦凝聚（BEC）这一成就的启发，以及提出的在薄壳上限制原子的气泡陷阱的启发，我们研究了球体表面上的 BEC 热力学。我们通过解析方法确定了非相互作用玻色气体的临界温度和凝聚分数。然后，我们考虑包含零范围原子间势，在零温及有限温下扩展非相互作用的结果。在非相互作用和相互作用的情况下，都强调了球体有限半径的关键作用，表明在无限半径极限下，人们可以恢复到熟悉的二维结果。我们还研究了由球体表面涡旋构型驱动的 Berezinskii-Kosterlitz-Thouless 相变，分析了在这个有限尺寸系统中凝聚和超流性的相互作用。
