Quantum phase slip

A superfluid shows several strange behaviors which are absent in a classical fluid. One such phenomenon that can be observed in superfluids is the nucleation of quantized vortices.  Consider the flow of a superfluid through a narrow channel. A vortex may nucleate in the fluid near its one edge due to thermal or quantum fluctuations, and it may roll across the channel. When this happens, the superfluid loses its phase and hence the velocity because the vortex carries energy with it and finally it dissipates as thermal energy. The loss in phase in such an event is 2pi. Such an event is called a quantum phase slip event or a velocity slip event. A quantum phase slip event can be utilized to detect rotation by using a toroidal supefluid in a superfliud gyroscope.