TY  - JOUR
AU  - Vool, U.
AU  - Pop, I. M.
AU  - Sliwa, K.
AU  - Abdo, B.
AU  - Wang, C.
AU  - Brecht, T.
AU  - Gao, Y. Y.
AU  - Shankar, S.
AU  - Hatridge, M.
AU  - Catelani, G.
AU  - Mirrahimi, M.
AU  - Frunzio, L.
AU  - Schoelkopf, R. J.
AU  - Glazman, L. I.
AU  - Devoret, M. H.
TI  - Non-Poissonian Quantum Jumps of a Fluxonium Qubit due to Quasiparticle Excitations
JO  - Physical review letters
VL  - 113
IS  - 24
SN  - 1079-7114
CY  - College Park, Md.
PB  - APS
M1  - FZJ-2014-07008
SP  - 247001
PY  - 2014
AB  - As the energy relaxation time of superconducting qubits steadily improves, nonequilibrium quasiparticle excitations above the superconducting gap emerge as an increasingly relevant limit for qubit coherence. We measure fluctuations in the number of quasiparticle excitations by continuously monitoring the spontaneous quantum jumps between the states of a fluxonium qubit, in conditions where relaxation is dominated by quasiparticle loss. Resolution on the scale of a single quasiparticle is obtained by performing quantum nondemolition projective measurements within a time interval much shorter than T1, using a quantum-limited amplifier (Josephson parametric converter). The quantum jump statistics switches between the expected Poisson distribution and a non-Poissonian one, indicating large relative fluctuations in the quasiparticle population, on time scales varying from seconds to hours. This dynamics can be modified controllably by injecting quasiparticles or by seeding quasiparticle-trapping vortices by cooling down in a magnetic field.
LB  - PUB:(DE-HGF)16
UR  - <Go to ISI:>//WOS:000346049700010
DO  - DOI:10.1103/PhysRevLett.113.247001
UR  - https://juser.fz-juelich.de/record/185582
ER  -