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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
BEGIN:VEVENT
SEQUENCE:3
UID:UW-Physics-Event-8387
DTSTART:20230914T150000Z
DTEND:20230914T230000Z
DTSTAMP:20260414T073950Z
LAST-MODIFIED:20230912T153817Z
LOCATION:5310 Chamberlin
SUMMARY:Strained Si/SiGe quantum wells with oscillating Ge concentrati
 on: valley and  spin-orbit physics\, R. G. Herb Condensed Matter Semin
 ar\,  Benjamin Woods\, UW-Madison
DESCRIPTION:Electron spin qubits in Si/SiGe quantum dots hold promise 
 for quantum computation due to their scalability and long coherence ti
 mes. However\, challenges persist\, notably small and variable valley 
 splitting introduces low-energy states near the qubit subspace\, causi
 ng decoherence and read-out difficulties. In addition\, reliance on ma
 gnetic field gradients from micromagnets in leading Si/SiGe qubit desi
 gns poses scalability issues. I will outline our solution to both prob
 lems\, which utilizes Si/SiGe heterostructures featuring long-waveleng
 th λ ≈ 1.7 nm Ge concentration oscillations and shear strain. For s
 uch a structure\, we show that the spin-orbit coupling is dramatically
  enhanced compared to conventional Si/SiGe quantum wells without Ge co
 ncentration oscillations. This enhancement permits
\nrapid spin manipu
 lation via electric dipole spin resonance without the need for microma
 gnets. Furthermore\, we show that the necessary level of shear strain 
 for valley splitting enhancement aligns with existing fabrication tech
 niques. Finally\, I will touch on promising future directions. This in
 cludes the exploration of electric dipole spin resonance under the inf
 luence of valley disorder and the potential for significant g-factor r
 enormalization in multi-electron quantum dots.
URL:https://www.physics.wisc.edu/events/?id=8387
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