Superconducting quasiparticles (QP) play a dominant role in the relaxation of the fluxonium qubit in the vicinity of the half-flux-quantum bias point. Recent experiments integrating the fluxonium with a quantum-limited amplifier have measured quantum jump trajectories between the ground state and the first excited state. These trajectories show a change in the characteristic lifetime of the fluxonium qubit as a function of time, arising from a change in the number of QP's in the sample [1]. Using a simple model of QP dynamics and their effect on the fluxonium qubit, we can access the QP population with temporal resolution better than a 100 microsecond. Such rapid monitoring of QP dynamics is essential for understanding the sources of QP's and ultimately suppressing them.\\[4pt] [1] ``Non-Poissonian quantum jumps of a fluxonium qubit due to quasiparticle excitations,'' U. Vool, I.M. Pop et al. to be published in PRL 2014.
*Work supported by: IARPA, ARO, and ONR.
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Authors
U. Vool
Department of Applied Physics, Yale University
Yale University
Yale Univ
I.M. Pop
Department of Applied Physics, Yale University
K. Sliwa
Department of Applied Physics, Yale University
B. Abdo
Department of Applied Physics, Yale University
C. Wang
Department of Applied Physics, Yale University
Y.Y. Gao
Department of Applied Physics, Yale University
A. Kou
Department of Applied Physics, Yale University
W.C. Smith
Department of Applied Physics, Yale University
T. Brecht
Department of Applied Physics, Yale University
S. Shankar
Department of Applied Physics, Yale University
M. Hatridge
Department of Applied Physics, Yale University
G. Catelani
Peter Gr\"unberg Institut (PGI-2), Forschungszentrum J\"ulich
L. Frunzio
Department of Applied Physics, Yale University
R.J. Schoelkopf
Department of Applied Physics, Yale University
L. Glazman
Department of Applied Physics, Yale University
M. Mirrahimi
Department of Applied Physics, Yale University and INRIA Paris Rocquencourt
