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VERSION:2.0
CALSCALE:GREGORIAN
PRODID:UW-Madison-Physics-Events
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SEQUENCE:1
UID:UW-Physics-Event-9758
DTSTART:20260807T153000Z
DTEND:20260807T173000Z
DTSTAMP:20260817T112453Z
LAST-MODIFIED:20260805T144708Z
LOCATION:5310 Chamberlin
SUMMARY:Qubit control in Si/SiGe: Hopping based single qubit gates\, P
 reliminary Exam\, Minyoung Kim\, Physics PhD Graduate Student
DESCRIPTION:Control of spin qubits in Si/SiGe is conventionally achiev
 ed through electric dipole spin resonance (EDSR)\, which requires a hi
 gh-frequency driving field and the accompanying heating that limits ga
 te performance. An alternative is the hopping gate\, in which an elect
 ron is shuttled between two quantum dots whose quantization axes are n
 on-parallel\, so that a universal gate is assembled from a sequence of
  wait times rather than by resonant driving. In this talk\, I will pre
 sent a systematic analysis of hopping-based universal single-qubit gat
 es and their implementation in the Wiggle Well\, a Si/SiGe heterostruc
 ture with oscillating Ge concentration which enhances intrinsic spin o
 rbit coupling and couples the tilt angle between quantization axes to 
 the valley phase of each dot. Because a physical ramp between charge c
 onfigurations takes finite time\, the evolution is decomposed into an 
 idealized rotation and a residual "kick" operator\, whose components c
 an be extracted experimentally from hopping oscillations and then comp
 ensated. Simulations including Landau-Zener leakage\, hyperfine fields
  from residual Si\, Ge isotopes\, and charge noise map the resulting i
 nfidelity landscape as a function of magnetic field and ramp time\, id
 entifying the regime in which high fidelity hopping gates are achievab
 le. Related work on tunnl-and valley-coupling measurment in double qua
 ntum dots and ongoing noise correlation spectroscopy with excahnge-onl
 y qubits will also be discussed.
URL:https://www.physics.wisc.edu/events/?id=9758
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