Quantum phase slip

Quantum phase slip (QPS) is a phenomenon that occurs in ultranarrow superconducting nanowires and other superconducting nanostructures. In a superconductor cooled below its critical temperature Tc, electrical current can flow without resistance. However, when the radius of a superconducting nanowire is sufficiently small, quantum energy fluctuations can cause portions of the nanowire instantaneously to enter the normal resistive state. The superconducting state is characterized by a wave function with an amplitude and phase. During a quantum fluctuation, the amplitude drops temporarily to zero. When this occurs, the phase is undefined and can jump by a multiple of 2π ( Fig. 1 a ). This is known as QPS and temporarily blocks the flow of current along the nanowire