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arXiv · 2503.13411

Mixed spin-boson coupling for qubit readout with suppressed residual shot-noise dephasing

Jinlun Hu·Antonio L. R. Manesco·André Melo·Taryn V. Stefanski·Christian Kraglund Andersen·Valla Fatemi
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Abstract

Direct dipole coupling between a two-level system and a bosonic mode describes the interactions present in a wide range of physical platforms. In this work, we study a coupling that is mixed between two pairs of quadratures of a bosonic mode and a spin. In this setting, we can suppress the dispersive shift while retaining a nonzero Kerr shift, which results in a quadratic relationship between shot-noise dephasing and thermal photons in the oscillator. We demonstrate this configuration with a simple toy model, quantify the expected improvements to photon shot-noise dephasing of the spin, and describe an approach to fast qubit readout via the Kerr shift. Further, we show how such a regime is achievable in superconducting circuits because magnetic and electric couplings can be of comparable strength, using two examples: the Cooper pair transistor and the fluxonium molecule.

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Jinlun Hu, Antonio L. R. Manesco, André Melo, Taryn V. Stefanski, Christian Kraglund Andersen, Valla Fatemi. 2025-03-17. Mixed spin-boson coupling for qubit readout with suppressed residual shot-noise dephasing. https://arxiv.org/abs/2503.13411

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