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arXiv · 0810.2372

Quantum dynamics in a camel-back potential of a dc SQUID

E. Hoskinson·F. Lecocq·N. Didier·A. Fay·F. W. J. Hekking·W. Guichard·R. Dolata·B. Mackrodt·A. B. Zorin·O. Buisson
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Abstract

We investigate the quantum dynamics of a quadratic-quartic anharmonic oscillator formed by a potential well between two potential barriers. We realize this novel potential shape with a superconducting circuit comprised of a loop interrupted by two Josephson junctions, with near-zero current bias and flux bias near half a flux quantum. We investigate escape out of the central well, which can occur via tunneling through either of the two barriers, and find good agreement with a generalized double-path macroscopic quantum tunneling theory. We also demonstrate that this system exhibits an "optimal line" in current and flux bias space along which the oscillator, which can be operated as a phase qubit, is insensitive to decoherence due to low-frequency current fluctuations.

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E. Hoskinson, F. Lecocq, N. Didier, A. Fay, F. W. J. Hekking, W. Guichard, R. Dolata, B. Mackrodt, A. B. Zorin, O. Buisson. 2008-10-14. Quantum dynamics in a camel-back potential of a dc SQUID. https://doi.org/10.1103/physrevlett.102.097004

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