Kinetics of quasiparticle trapping in a Cooper-pair box

Abstract

We study the kinetics of the quasiparticle capture and emission process in a small superconducting island (Cooper-pair box) connected by a tunnel junction to a massive superconducting lead. At low temperatures, the charge on the box fluctuates between two states, even and odd in the number of electrons. Assuming that the odd-electron state has the lowest energy, we evaluate the distribution of lifetimes of the even- and odd-electron states of the Cooper-pair box. The lifetime in the even-electron state is an exponentially distributed random variable corresponding to a homogenous Poisson process of ``poisoning'' the island with a quasiparticle. The distribution of lifetimes of the odd-electron state may deviate from the exponential one. The deviations come from two sources - the peculiarity of the quasiparticle density of states in a superconductor and the possibility of quasiparticle energy relaxation via phonon emission. In addition to the lifetime distribution, we also find spectral density of charge fluctuations generated by capture and emission processes. The complex statistics of the quasiparticle dwell times in the Cooper-pair box may result in strong deviations of the noise spectrum from the Lorentzian form.

final version as published in PRB, 14 pages, 9 figures

References in corpus (4)

• Quasiparticle decay rate of Josephson charge qubit oscillations
• Microsecond resolution of quasiparticle tunneling in the single-Cooper-pair-transistor
• Time-domain measurements of quasiparticle tunneling rates in a single-Cooper-pair transistor
• Kinetics of the superconducting charge qubit in the presence of a quasiparticle

Cited by in corpus (7)

• Kinetics of non-equilibrium quasiparticle tunneling in superconducting charge qubits
• A quantitative study of quasiparticle traps using the single-Cooper-pair-transistor
• Fast readout of a single Cooper-pair box using its quantum capacitance
• The parity effect in Josephson junction arrays
• Effect of quantum fluctuations on even-odd energy difference in a Cooper-pair box
• The Quantum Capacitor Detector: A Single Cooper Pair Box Based Readout for Pair Breaking Photo-detectors
• Electron-phonon interactions in the Andreev Bound States of aluminum nanobridge Josephson junctions