Coexistence of Nonequilibrium Density and Equilibrium Energy Distribution of Quasiparticles in a Superconducting Qubit
T. Connolly, Pavel D. Kurilovich, Spencer Diamond, Heekun Nho, C. G. L. Bøttcher, L. I. Glazman, Valla Fatemi, Michel Devoret
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.
Topics & Concepts
QuasiparticleSuperconductivityQubitCondensed matter physicsNon-equilibrium thermodynamicsPhysicsDistribution (mathematics)Phase qubitSuperconducting quantum computingQuantum mechanicsQuantumJosephson effectMathematical analysisMathematicsQuantum and electron transport phenomenaPhysics of Superconductivity and MagnetismQuantum Information and Cryptography