论文标题
超速玻色气体中的cNoidal波的超偏度
Supersolidity of cnoidal waves in an ultracold Bose gas
论文作者
论文摘要
一维的玻色污水凝结物可能会经历非线性周期性调制，称为“ cNoidal波”。我们认为，这样的结构代表了在非平衡状态下与超摩尔相关现象研究的有希望的候选者。一种平均场地的处理使得可以为系统的超流体分数重新使用Leggett的公式，并通过分析进行估算。我们确定了激发频谱，为此，我们在（i）线性调制背景和（ii）一列深色孤子的两个相反限制情况下获得了分析结果。在大波长处，存在两个金石（无间隙）模式 - 与$ \ mathrm {u}（1）$对称性和连续转换不变性的自发断裂相关联。我们还计算了cNoidal波的静态结构因子和可压缩性，这些因子在每个布里渊区的边缘显示出不同的行为。
A one-dimensional Bose-Einstein condensate may experience nonlinear periodic modulations known as "cnoidal waves". We argue that such structures represent promising candidates for the study of supersolidity-related phenomena in a non-equilibrium state. A mean-field treatment makes it possible to rederive Leggett's formula for the superfluid fraction of the system and to estimate it analytically. We determine the excitation spectrum, for which we obtain analytical results in the two opposite limiting cases of (i) a linearly modulated background and (ii) a train of dark solitons. The presence of two Goldstone (gapless) modes -- associated with the spontaneous breaking of $\mathrm{U}(1)$ symmetry and of continuous translational invariance -- at large wavelength is verified. We also calculate the static structure factor and the compressibility of cnoidal waves, which show a divergent behavior at the edges of each Brillouin zone.
