Andreev spin qubit protected by Franck-Condon blockade

Fuente: arXiv
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Main Authors: Kurilovich, P. D., Vakhtel, T., Connolly, T., Bøttcher, C. G. L., van Heck, B.
Format: Preprint
Published: 2025
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_version_ 1866915893903097856
author Kurilovich, P. D.
Vakhtel, T.
Connolly, T.
Bøttcher, C. G. L.
van Heck, B.
author_facet Kurilovich, P. D.
Vakhtel, T.
Connolly, T.
Bøttcher, C. G. L.
van Heck, B.
contents Andreev levels localized in a weak link between two superconductors can trap a superconducting quasiparticle. If there is a spin-orbit coupling in the link, the spin of the quasiparticle couples to the Josephson current. This effect can be leveraged to control and readout the spin of the quasiparticle thus using it as a qubit. One of the factors limiting the performance of such an Andreev spin qubit is spin relaxation. Here, we theoretically demonstrate that the relaxation lifetime can be enhanced by utilizing the coupling between the Andreev spin and the supercurrent in a transmon circuit. The coupling ensures that the flip of the quasiparticle spin can only happen if it is accompanied by the excitation of multiple plasmons, as dictated by the Franck-Condon principle. This blocks spin relaxation at temperatures small compared to plasmon energy.
format Preprint
id arxiv_https___arxiv_org_abs_2506_08568
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Andreev spin qubit protected by Franck-Condon blockade
Kurilovich, P. D.
Vakhtel, T.
Connolly, T.
Bøttcher, C. G. L.
van Heck, B.
Mesoscale and Nanoscale Physics
Andreev levels localized in a weak link between two superconductors can trap a superconducting quasiparticle. If there is a spin-orbit coupling in the link, the spin of the quasiparticle couples to the Josephson current. This effect can be leveraged to control and readout the spin of the quasiparticle thus using it as a qubit. One of the factors limiting the performance of such an Andreev spin qubit is spin relaxation. Here, we theoretically demonstrate that the relaxation lifetime can be enhanced by utilizing the coupling between the Andreev spin and the supercurrent in a transmon circuit. The coupling ensures that the flip of the quasiparticle spin can only happen if it is accompanied by the excitation of multiple plasmons, as dictated by the Franck-Condon principle. This blocks spin relaxation at temperatures small compared to plasmon energy.
title Andreev spin qubit protected by Franck-Condon blockade
topic Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2506.08568