Effects of charging-energy fluctuations on an anomalous behavior of mesoscopic Josephson junctions

Abstract

A theory is proposed for mesoscopic Josephson junctions in the low-temperature intermediate quantum regime in which such junctions are characterized by a large single-electron charging energy {ital E}{sub {ital c}} that is of the order of the Josephson energy, {ital E}{sub {ital J}}. This contrasts with the classical Josephson junctions where the Josephson energy {ital E}{sub {ital J}} is usually dominant. In this intermediate regime the phase difference of the order parameters for left and right superconductors is no longer localized. In particular, it is believed that at low temperature the quantum phase fluctuations play a very important role. By employing functional-integral methods to the junction Hamiltonian, the resistive regimes of the mesoscopic Josephson junctions below the critical current are studied. It is shown that the Josephson current acquires a spectral decomposition, characterized by the spectral width {Delta}{sub {omega}}. The relative values of {Delta}{sub {omega}} and the voltage {ital V} are shown to determine the resistive regimes in the junction.