Evidence for Quantum Phase Slip Events in Superconducting Nanowires at High Bias Current.pdf

1 Evidence for Quantum Phase Slip Events in Superconducting Nanowires at High Bias Current Mitrabhanu Sahu1, Myung-Ho Bae1, Andrey Rogachev1, 2, David Pekker1, 3, Tzu-Chieh Wei1, 4, Nayana Shah1, Paul M. Goldbart1 and Alexey Bezryadin1 1Department of Physics, University of Illinois at Urbana Champaign 2Department of Physics, University of Utah 3Department of Physics, Harvard University 4Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo Slips in the phase of the superconducting order-parameter field are the cause of energy dissipation and quantum decoherence in thin superconducting nanowires. At low temperatures, these phase slips are expected to occur via quantum tunneling of the order-parameter field. The precise conditions for the occurrence of such tunneling have not been established firmly. We address the challenge of observing quantum phase slips via measurements of the distribution of switching currents— the high-bias currents at which superconductivity gives way to resistive behavior. In Mo79Ge21 nanowires we observe a monotonic increase in the width of this distribution with decreasing temperature, which is consistent with a model that incorporates Joule-heating from stochastically-occurring phase slips. This model suggests that the phase predominantly slips via thermal activation at high temperatures but via quantum tunneling at low temperatures. At sufficiently low temperatures, switching is caused by individual quantum phase-slip events. 2 Quantum phenomena involving systems far larger than individual atoms are one of the most exciting fields of modern physics. Initiated by Leggett more than twenty-five years ago (1-3), the field has seen widespread development, important realizations being furnished, e. g., by macroscopic quantum tunneling (MQT) of the phase in Josephson junctions, and of the magnetization in magnetic nanoparticles (4-7). More recently, the breakth