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PRODID:UW-Madison-Physics-Events
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SEQUENCE:0
UID:UW-Physics-Event-3277
DTSTART:20140403T150000Z
DURATION:PT1H0M0S
DTSTAMP:20210116T170143Z
LAST-MODIFIED:20140324T160314Z
LOCATION:Chamberlin 5310
SUMMARY:Measuring topological transitions in superconducting qubits\,
R. G. Herb Condensed Matter Seminar\, Michael Kolodrubetz\, Boston Uni
versity
DESCRIPTION:The field of topological insulators sprung from the realiz
ation that in the presence of spin-orbit coupling\, non-interacting el
ectrons can have a band structure that non-trivially wraps the first B
rillouin zone. From the gauge-invariant Berry curvature that locally
defines the geometry of this wrapping\, one can define an integer topo
logical invariant – the Chern number – from which all other invari
ants derive. We investigate the Berry curvature and Chern number of a
n even simpler case: single and double spin-1/2 systems (qubits) in a
rotating magnetic field. We show that these simple systems undergo to
pological transitions of their Chern number\, which for the case of th
e single qubit can be directly mapped to the topological transitions o
f the Haldane model of graphene. Furthermore\, we experimentally demon
strate such a topological transition in a single superconducting qubit
\, measuring the Berry curvature as a leading order correction to line
ar response. We then generalize the methods to two-qubit systems\, wh
ere we experimentally measure the topological phase diagram and demons
trate interaction-driven topological transitions.
URL:https://www.physics.wisc.edu/events/?id=3277
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