超流费米气体中两维孤子的动力学

我们利用解析和数值的方法,研究从Bardeen-Cooper-Schrieffer(BCS)超流到玻色-爱因斯坦凝聚(BEC)渡越的过程里超流费米气体中两维(2D)孤子的形成和演化.基于超流流体力学方程,在准二维和长波近似下,推导描述弱非线性激发带正色散项的Kadomtsev-Petviashvili方程;给出整个BCS-BEC渡越的2D孤子解,以及数值求解孤子在囚禁势中的演化.数值结果显示由于Snake(横向)不稳定性,大振幅的暗孤子会衰变为大量涡旋-反涡旋对,并且这个不稳定性在不同超流区域不同.

Dynamics of two-dimensional solitons in superfluid Fermi gases

We study, both analytically and numerically, the formation and dynamics of two-dimensional (2D) solitons in the superfluid Fermi gas along a crossover from Bardeen-Cooper-Schrieffer (BCS) superfluid to a Bose-Einstein condensate (BEC). Based on the superfluid hydrodynamic equations we derive a Kadomtsev-Petriashvili equation with positive dispersion describing weak nonlinear excitations, under the quasi two-dimension (2D) and long-wavelength approximations. We present 2D soliton solutions in the BCS-BEC crossover, and numerical results for the dynamics of solitons in the presence of the trapping potential. It is shown that high-depth dark solitons decay into a large number of vortex-antivortex pairs due to the snake (transverse) instability, which display different behavior in different superfluid regimes.