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PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:0
UID:UW-Physics-Event-2855
DTSTART:20130502T150000Z
DURATION:PT1H0M0S
DTSTAMP:20260412T095448Z
LAST-MODIFIED:20130429T151249Z
LOCATION:5310 Chamberlin
SUMMARY:Bulk Phononic Crystal as Quantum  Information Bus between Shal
 low Donor Spins\, R. G. Herb Condensed Matter Seminar\, Vadim Smelyans
 kiy\, NASA\, Ames Research Center
DESCRIPTION:We propose a new candidate for a spin qubit based on shall
 ow donor spins in the semiconductor with very low isotopic concentrati
 on of nuclear spins and with spin orbital interaction many orders of m
 agnitude stronger than that in silicon.  In a uniform material this in
 teraction leads to a short spin lifetimes. However we show that this l
 ifetime increases dramatically when  donor spin is placed in quasi-2D 
 bulk phononic crystal (PnC) with the energy of a Zeeman splitting  bei
 ng  inside of a complete phononic  bandgap. In this situation single p
 honon processes are suppressed by energy conservations. We show that t
 wo-phonon decay remains very slow while virtual phonon exchange leads 
 to a strong coupling between donor spins.  We show that resonance cohe
 rent excitation transfer between the spins is enhanced exponentially w
 hen their Zeeman splitting is tuned near the phononic crystal band edg
 e.  We also show that long-range longitudinal interaction (z-z) betwee
 n spins in PnC is very similar to then one mediated by Lamb waves in e
 lastic plate.  We explore various PnC cell shapes and proportions to m
 aximize the above coherent effects and minimize the decay rate\, focus
 ing mainly on the quasi-2D square "Cross" crystal type initially propo
 sed by Safavi-Naeini and Painter. We show that the system is a very in
 teresting candidate for the quantum computing applications with unit c
 ell size ~ 100-150nm. 
URL:https://www.physics.wisc.edu/events/?id=2855
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