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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-2635
DTSTART:20120423T213000Z
DURATION:PT1H0M0S
DTSTAMP:20260420T062248Z
LAST-MODIFIED:20120417T162515Z
LOCATION:5310 Chamberlin
SUMMARY:Two-electron dephasing in single Si and GaAs quantum dots\, Co
 ndensed Matter Theory Group Seminar\, John Gamble\, UW-Madison
DESCRIPTION:We study the dephasing of two-electron states in a single 
 quantum dot in both GaAs and Si. We investigate dephasing induced by e
 lectron-phonon coupling and by charge noise analytically for pure orbi
 tal excitations in GaAs and Si\, as well as for pure valley excitation
 s in Si. In GaAs\, polar optical phonons give rise to the most importa
 nt contribution\, leading to GHz dephasing rates. For Si\, intervalley
  optical phonons lead to typical dephasing rates of ~100 kHz for orbit
 al excitations and ~1 MHz for valley excitations. For harmonic\, disor
 der-free quantum dots\, charge noise is highly suppressed for both orb
 ital and valley excitations\, since neither has an appreciable dipole 
 moment to couple to electric field variations from charge fluctuators.
  However\, both anharmonicity and disorder break the symmetry of the s
 ystem\, which can lead to increased dipole moments and therefore faste
 r dephasing rates. 
URL:https://www.physics.wisc.edu/events/?id=2635
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