Decoherence processes in a current biased dc SQUID

Abstract

A current bias dc SQUID behaves as an anharmonic quantum oscillator controlled by a bias current and an applied magnetic flux. We consider here its two level limit consisting of the two lower energy states $| 0 \right>$ and $| 1 \right>$. We have measured energy relaxation times and microwave absorption for different bias currents and fluxes in the low microwave power limit. Decoherence times are extracted. The low frequency flux and current noise have been measured independently by analyzing the probability of current switching from the superconducting to the finite voltage state, as a function of applied flux. The high frequency part of the current noise is derived from the electromagnetic environment of the circuit. The decoherence of this quantum circuit can be fully accounted by these current and flux noise sources.

4 pages, 4 figures

Cited by in corpus (8)

• Decoherence of flux qubits due to 1/f flux noise
• Strong tunable coupling between a superconducting charge and phase qubit
• Rabi-like oscillations of an anharmonic oscillator: classical versus quantum interpretation
• Maximally entangling tripartite protocols for Josephson phase qubits
• Nanosecond quantum state detection in a current biased dc SQUID
• Quantum measurements without macroscopic superpositions
• Dissipative dynamics of circuit-QED in the mesoscopic regime
• Measuring the distribution of current fluctuations through a Josephson junction with very short current pulses