Josephson effect and quantum fluctuations

G.-L. Ingold and H. Grabert

Physica B 284, 1824–1825 (2000) DOI: 10.1016/S0921-4526(99)03035-5

Phase fluctuations destroy the dc Josephson effect and replace the supercurrent at zero voltage by a peak at small but finite voltages. We study the effect of quantum fluctuations of the phase at zero temperature by accounting for a finite junction capacitance and an environmental resistance. The Josephson peak is expressed analytically by two complementary expansions. This result establishes the connection between the regimes of classical phase diffusion, Coulomb blockade and macroscopic quantum tunneling.