The quantum phase slip phenomenon in superconducting nanowires with high-impedance environment
The topic of quantum fluctuations in quasi-1D superconductors, also called quantum phase slips (QPS), has attracted a significant attention. It has been shown that the phenomenon is capable to suppress zero resistivity of ultra-narrow superconducting nanowires at low temperatures T<<Tc and quench persistent currents in tiny nanorings. It has been predicted that a superconducting nanowire in the regime of QPS is dual to a Josephson junction. In particular case of an extremely narrow superconducting nanowire imbedded in high-impedance environment the duality leads to an intuitively controversial result: the superconductor can enter an insulating state. Here we experimentally demonstrate that the I-V characteristic of such a wire indeed shows Coulomb blockade which disappears with application of critical magnetic field and/or above the critical temperature proving that the effect is related to superconductivity. The system can be considered as a dynamic equivalent of a conventional Josephson junction containing static in space and time weak link(s).