Coherent quantum phase slip

摘要

A hundred years after the discovery of superconductivity, one fundamental prediction of the theory, coherent quantum phase slip (CQPS), has not been observed. CQPS is a phenomenon exactly dual~1 to the Josephson effect; whereas the latter is a coherent transfer of charges between superconducting leads2'3, the former is a coherent transfer of vortices or fluxes across a superconducting wire. In contrast to previously reported observations4" of incoherent phase slip, CQPS has been only a subject of theoretical study~(9-12). Its experimental demonstration is made difficult by quasipartide dissipation due to gapless excitations in nanowires or in vortex cores. This difficulty might be overcome by using certain strongly disordered superconductors near the superconductor-insulator transition. Here we report direct observation of CQPS in a narrow segment of a superconducting loop made of strongly disordered indium oxide; the effect is made manifest through the superposition of quantum states with different numbers of flux quanta13. As with the Josephson effect, our observation should lead to new applications in superconducting electronics and quantum metrology.%“相干量子相滑移”(CQPS)此前直没有在实rn验中观测到。它是一个与“约瑟夫森效应”正rn好对偶的现象，但后者是电荷在超导接触点之rn间的一种相干转移，而CQPS则是涡流或通量rn在整个一根超导线上的一种相干转移。这篇论rn文报告了对插入在一个环中的根强紊乱的氧rn化铟超导线中的cQPs的直接观测．其效应通rn过具有不同通量的量子态的重叠显示出来。同rn其之前的“约瑟夫森效应”一样，CQPS也可能rn会导致超导电子学和量子计量学中创新应用的rn问世。