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arXiv · 2302.12330

Coexistence of nonequilibrium density and equilibrium energy distribution of quasiparticles in a superconducting qubit

Thomas Connolly·Pavel D. Kurilovich·Spencer Diamond·Heekun Nho·Charlotte G. L. Bøttcher·Leonid I. Glazman·Valla Fatemi·Michel H. Devoret
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Abstract

The density of quasiparticles typically observed in superconducting qubits exceeds the value expected in equilibrium by many orders of magnitude. Can this out-of-equilibrium quasiparticle density still possess an energy distribution in equilibrium with the phonon bath? Here, we answer this question affirmatively by measuring the thermal activation of charge-parity switching in a transmon qubit with a difference in superconducting gap on the two sides of the Josephson junction. We then demonstrate how the gap asymmetry of the device can be exploited to manipulate its parity.

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Thomas Connolly, Pavel D. Kurilovich, Spencer Diamond, Heekun Nho, Charlotte G. L. Bøttcher, Leonid I. Glazman, Valla Fatemi, Michel H. Devoret. 2023-02-23. Coexistence of nonequilibrium density and equilibrium energy distribution of quasiparticles in a superconducting qubit. https://doi.org/10.1103/physrevlett.132.217001

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