Nonequilibrium quasiparticle distribution in superconducting resonators: analytical approach

Abstract

In the superconducting state, the presence of a finite gap in the excitation spectrum implies that the number of excitations (quasiparticles) is exponentially small at temperatures well below the critical one. Conversely, minute perturbations can significantly impact both the distribution in energy and number of quasiparticles. Typically, the interaction with the electromagnetic environment is the main perturbation source driving quasiparticles out of thermal equilibrium, while a phonon bath is responsible for restoration of equilibrium. Here we derive approximate analytical solutions for the quasiparticle distribution function in superconducting resonators and explore the impact of nonequilibrium on two measurable quantities: the resonator's quality factor and its resonant frequency. Applying our results to experimental data, we conclude that while at intermediate temperatures there is clear evidence for the nonequilibrium effects due to heating of the quasiparticles by photons, the low-temperature measurements are not explained by this mechanism.

22 pages, 8 figures

References in corpus (5)

• Superconducting nanowire single-photon detectors: physics and applications
• Using materials for quasiparticle engineering
• Effect of Quasiparticles Injection on the AC Response of a Superconductor
• The discovery, disappearance and re-emergence of radiation-stimulated superconductivity
• Dissipation in a superconducting artificial atom due to a single non-equilibrium quasiparticle

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• Theory of quasiparticle-induced errors in driven-dissipative Schrödinger cat qubits
• Superconducting surface trap chips for microwave-driven trapped ions
• Excess quasiparticles and their dynamics in the presence of subgap states
• Volume dependence of microwave induced excess quasiparticles in superconducting resonators
• Exploring van der Waals cuprate superconductors using a hybrid microwave circuit
• Enhanced Athermal Phonon Responsivity in a Kinetic Inductance Detector with Integrated Phonon Collectors