Decoherence in Andreev spin qubits
Abstract: We theoretically study the dephasing of an Andreev spin qubit (ASQ) due to electric and magnetic noise. Using a tight-binding model, we calculate the Andreev states formed in a Josephson junction where the link is a semiconductor with strong spin-orbit interaction. As a result of both the spin-orbit interaction and induced superconductivity, the local charge and spin of these states varies as a function of externally controllable parameters: the phase difference between the superconducting leads, an applied magnetic field, and filling of the underlying semiconductor. Concomitantly, coupling to fluctuations of the electric or magnetic environment will vary, which informs the rate of dephasing. We qualitatively predict the dependence of dephasing on the nature of the environment, magnetic field, phase difference between the junction, and filling of the semiconductor. Comparing the simulated electric- and magnetic-noise-induced dephasing rate to experiment suggests that the dominant source of noise is magnetic. Moreover, by appropriately tuning these external parameters, we find sweet-spots at which we predict an enhancement in ASQ coherence times.
- I. Kulik, Soviet Journal of Experimental and Theoretical Physics 30, 944 (1969).
- C. Beenakker and H. Van Houten, Phys. Rev. Lett. 66, 3056 (1991).
- A. Furusaki and M. Tsukada, Phys. Rev. B 43, 10164 (1991).
- S. Park and A. L. Yeyati, Phys. Rev. B 96, 125416 (2017).
- A. Bargerbos, M. Pita-Vidal, R. ´itko, L. J. Splitthoff, L. Grünhaupt, J. J. Wesdorp, Y. Liu, L. P. Kouwenhoven, R. Aguado, C. K. Andersen, A. Kou, and B. van Heck, “Spectroscopy of spin-split andreev levels in a quantum dot with superconducting leads,” (2022), arXiv:2208.09314 [cond-mat.mes-hall] .
- N. M. Chtchelkatchev and Y. V. Nazarov, Phys. Rev. Lett. 90, 226806 (2003).
- C. Padurariu and Y. V. Nazarov, Phys. Rev. B 81, 144519 (2010).
- According to the form found in Eq. 1, the eigenstates of have spin only along the z𝑧zitalic_z axis.
- Y. V. Nazarov and Y. M. Blanter, Quantum transport: introduction to nanoscience (Cambridge university press, 2009).
- The position of the maximum and minimum qubit frequency can be reversed by effectively reversing the direction of the magnetic field, i.e. Bz→−Bz→superscript𝐵𝑧superscript𝐵𝑧B^{z}\rightarrow-B^{z}italic_B start_POSTSUPERSCRIPT italic_z end_POSTSUPERSCRIPT → - italic_B start_POSTSUPERSCRIPT italic_z end_POSTSUPERSCRIPT.
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