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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-3905
DTSTART:20160310T160000Z
DTEND:20160310T170000Z
DTSTAMP:20260419T145314Z
LAST-MODIFIED:20160304T191045Z
LOCATION:Chamberlin 5310
SUMMARY:Phonon-mediated decay of singlet-triplet qubits in double quan
 tum dots in GaAs/AlGaAs and Si/SiGe heterostructures\, R. G. Herb Cond
 ensed Matter Seminar\, Viktoriia Kornich\, University of Basel
DESCRIPTION:We study theoretically the phonon-induced relaxation and d
 ecoherence times of singlet-triplet qubits in lateral double quantum d
 ots (DQDs) in GaAs/AlGaAs and Si/SiGe heterostructures. We show that t
 he two-phonon processes can dominate over the one-phonon processes eve
 n at rather low temperature\, e.g. for the decoherence time at 50 mK f
 or biased GaAs/AlGaAs DQDs. We find that when the DQD is unbiased the 
 qubit lifetimes are orders of magnitude longer than for the case of bi
 ased DQD. The lifetimes of the qubits in Si/SiGe DQDs are remarkably l
 onger than the ones in GaAs/AlGaAs DQDs\, and following interest in S-
 T_- qubits we consider the phonon-induced decoherence and relaxation p
 articularly in the region of the singlet-triplet anticrossing. We show
  that the hybridization of the singlet state plays a crucial role. Amo
 ng other parameters of the system\, we study the effect of micromagnet
 -induced magnetic field gradient on the qubit\, which reveals an non-t
 rivial behavior of the relaxation and decoherence times as a result of
  interplay between one-phonon and two-phonon processes. We suggest how
  our theory can be tested experimentally. 
URL:https://www.physics.wisc.edu/events/?id=3905
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