Refael, Gil and Demler, Eugene and Oreg, Yuval and Fisher, Daniel S. (2003) Dissipation and quantum phase transitions of a pair of Josephson junctions. Physical Review B, 68 (21). Art. No. 214515. ISSN 0163-1829 http://resolver.caltech.edu/CaltechAUTHORS:REFprb03
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A model system consisting of a mesoscopic superconducting grain coupled by Josephson junctions to two macroscopic superconducting electrodes is studied. We focus on the effects of Ohmic dissipation caused by resistive shunts and superconducting-normal charge relaxation within the grain. As the temperature is lowered, the behavior crosses over from uncoupled Josephson junctions, similar to situations analyzed previously, to strongly interacting junctions. The crossover temperature is related to the energy-level spacing of the grain and is of the order of the inverse escape time from the grain. In the limit of zero temperature, the two-junction system exhibits five distinct quantum phases, including a novel superconducting state with localized Cooper pairs on the grain but phase coherence between the leads due to Cooper pair cotunneling processes. In contrast to a single junction, the transition from the fully superconducting to fully normal phases is found to be controlled by an intermediate-coupling fixed point whose critical exponents vary continuously as the resistances are changed. The model is analyzed via two-component sine-Gordon models and related Coulomb gases that provide effective low-temperature descriptions in both the weak and strong Josephson coupling limits. The complicated phase diagram is consistent with symmetries of the two component sine-Gordon models, which include weak- to strong-coupling duality and permutation triality. Experimental consequences of the results and potential implications for superconductor to normal transitions in thin wires and films are discussed briefly.
|Additional Information:||©2003 The American Physical Society Received 2 March 2003; revised 7 October 2003; published 24 December 2003 We would like to thank A. Amir, A. Bezryadin, S. Chakravarty, M. Dykman, E. Fradkin, L. Glazman, B. Halperin, W. Hofstetter, Y. Imry, R. Kapon, S. Kivelson, N. Markovic, D. Podolsky, L. Pryadko, M. Tinkham, and G. Zarand for helpful discussions. This research was supported by the National Science Foundation via Grant Nos. DMR-0132874 (E.D.) and DMR-9976621 (G.R., Y.O., and D.S.F.), by Harvard’s Materials Research Science and Engineering Center, by the Sloan Foundation (E.D.), and by the Israeli Science Foundation via Grant No. 160/01-1 (Y.O.).|
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|Deposited On:||09 Jan 2007|
|Last Modified:||26 Dec 2012 09:29|
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