Spontaneous Symmetry Breaking of Vortex Number in Binary Alternating Current Countersuperflow

In binary superfluid counterflow systems, vortex nucleation arises as a consequence of hydrodynamic instabilities when the coupling coefficient and counterflow velocity exceed the critical value. When dealing with two identical components, one might naturally anticipate that the number of vortices generated would remain equal. However, through the numerical experiments of the holographic model and the Gross-Pitaevskii equation, our investigation has unveiled a remarkable phenomenon: in Alternating Current counterflow systems, once the coupling coefficient and frequency exceed certain critical values, a surprising symmetry-breaking phenomenon occurs. This results in an asymmetry in the number of vortices in the two components. We establish that this phenomenon represents a novel continuous phase transition, which, as indicated by the phase diagram, is exclusively observable in Alternating Current counterflow. We provide an explanation for this intriguing phenomenon through soliton structures, thereby uncovering the complex and unique characteristics of quantum fluid instabilities and their rich phenomena.