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Phase-slip flux qubits

J. E. Mooij·C. J. P. M. Harmans
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Abstract

In thin superconducting wires, phase-slip by thermal activation near the critical temperature is a well-known effect. It has recently become clear that phase-slip by quantum tunnelling through the energy barrier can also have a significant rate at low temperatures. In this paper it is suggested that quantum phase-slip can be used to realize a superconducting quantum bit without Josephson junctions. A loop containing a nanofabricated very thin wire is biased with an externally applied magnetic flux of half a flux quantum, resulting in two states with opposite circulating current and equal energy. Quantum phase-slip should provide coherent coupling between these two macroscopic states. Numbers are given for a wire of amorphous niobium-silicon that can be fabricated with advanced electron beam lithography.

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J. E. Mooij, C. J. P. M. Harmans. 2005-08-18. Phase-slip flux qubits. https://doi.org/10.1088/1367-2630%2F7%2F1%2F219

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