Quantum-geometric perspective on spin-orbit-coupled Bose superfluids

Abstract

We employ the Bogoliubov approximation to study how the quantum geometry of the helicity states affects the superfluid properties of a spin-orbit-coupled Bose gas in continuum. In particular we derive the low-energy Bogoliubov spectrum for a plane-wave condensate in the lower helicity band and show that the geometric contributions to the sound velocity are distinguished by their linear dependences on the interaction strength; that is, they are in sharp contrast to the conventional contribution which has a square-root dependence. We also discuss the roton instability of the plane-wave condensate against the stripe phase and determine their phase-transition boundary. In addition we derive the superfluid density tensor by imposing a phase twist on the condensate order parameter and study the relative importance of its contribution from the interband processes that is related to the quantum geometry.

Spin-Orbit Coupled Dynamics of Ferromagnetic Spinor Bose-Einstein Condensate

“…In addition, the aspect ratio is easily adjusted by manipulating the trap frequency. It has been shown that the trap geometry issue has been widely discussed in recent years [39,40]. We point out that the discussions above are confined to isotropy SOC strength.…”