Relaxation and Dephasing in a Flux-qubit

Abstract

We report detailed measurements of the relaxation and dephasing time in a flux-qubit measured by a switching DC SQUID. We studied their dependence on the two important circuit bias parameters: the externally applied magnetic flux and the bias current through the SQUID in two samples. We demonstrate two complementary strategies to protect the qubit from these decoherence sources. One consists in biasing the qubit so that its resonance frequency is stationary with respect to the control parameters ({\it optimal point}) ; the second consists in {\it decoupling} the qubit from current noise by chosing a proper bias current through the SQUID. At the decoupled optimal point, we measured long spin-echo decay times of up to $4\mu s$.

arXiv comment4 pages, 4 figures, submitted to Phys. Rev. Letters

Cited by in corpus (6)

• 1/f noise: implications for solid-state quantum information
• Decoherence in Solid State Qubits
• Optimized controlled Z gates for two superconducting qubits coupled through a resonator
• Circuit QED with a Flux Qubit Strongly Coupled to a Coplanar Transmission Line Resonator
• Efficient evaluation of decoherence rates in complex Josephson circuits
• Reduced visibility of quantum oscillations in the spin-boson model