Article abstract
Nature Physics 5, 503 - 508 (2009)
Published online: 17 May 2009 | doi:10.1038/nphys1276
Subject Categories: Condensed-matter physics | Nanotechnology | Materials physics
Individual topological tunnelling events of a quantum field probed through their macroscopic consequences
Mitrabhanu Sahu1, Myung-Ho Bae1, Andrey Rogachev1,2, David Pekker1,3, Tzu-Chieh Wei1,4, Nayana Shah1, Paul M. Goldbart1 & Alexey Bezryadin1
Abstract
Phase slips are topological fluctuations that carry the superconducting order-parameter field between distinct current-carrying states. Owing to these phase slips, superconducting nanowires acquire electrical resistance. In such wires, it is well known that at higher temperatures phase slips occur through the process of thermal barrier-crossing by the order-parameter field. At low temperatures, the general expectation is that phase slips should proceed through quantum tunnelling events, which are known as quantum phase slips. However, resistive measurements have produced evidence both for and against the occurrence of quantum phase slips. Here, we report evidence for the observation of individual quantum phase-slip events in homogeneous ultranarrow wires at high bias currents. We accomplish this through measurements of the distribution of switching currents for which the width exhibits a rather counter-intuitive, monotonic increase with decreasing temperature. Importantly, measurements show that in nanowires with larger critical currents, quantum fluctuations dominate thermal fluctuations up to higher temperatures.
- Department of Physics, University of Illinois at Urbana Champaign, 1110 West Green Street, Urbana, Illinois 61801, USA
- Department of Physics, University of Utah, 115 S 1400 E, Salt Lake City, Utah 84112, USA
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, Massachusetts 02138, USA
- Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, 200 University Ave. W., Waterloo, Ontario N2L 3G1, Canada
Correspondence to: Mitrabhanu Sahu1 e-mail: sahu@illinois.edu
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