Decoherence and dephasing in coupled Josephson-junction qubits

We investigate the decoherence and dephasing of two coupled Josephson qubit s. With the interaction between the qubits being generated by current-curre nt correlations, two different situations in which the qubits are coupled t o the same bath, or to two independent baths, are considered. Upon focussin g on dissipation being caused by the fluctuations of voltage sources, the r elaxation and dephasing rates are explicitly evaluated. Analytical and nume rical results for the coupled qubits dynamics are provided. (C) 2001 Elsevi er Science B.V. All rights reserved.