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CATEGORIES:Theoretical Physics Seminars
SUMMARY:Topological classes of quasi-periodically driven q
uantum dynamics\, and the transitions between them
- Philip Crowley (Boston University)
DTSTART:20190711T130000Z
DTEND:20190711T140000Z
UID:TALK3824AT
URL:/talk/index/3824
DESCRIPTION:Few level quantum systems driven by multiple incom
mensurate tones exhibit temporal analogues of non-
interacting phenomena in spatial dimensions. Analo
gous to the bands of a two-dimensional lattice\, f
or two drives the pre-thermal dynamics of a driven
qudit can be classified according to a Chern numb
er. We show that non-zero Chern numbers lead to dr
amatic dynamical signatures\, including chaotic se
nsitivity to initial conditions\, and aperiodic ti
me dynamics of expectation values\, and the intege
r-quantised pumping of energy from one drive to th
e other – a temporal analogue to the quantum hall
effect.\n \nWe then study the transition between t
he non-trivial and trivial classes of pre-thermal
dynamics. The transition is asymptotically sharp i
n the limit of zero frequency and is characterised
by a Dirac point in the instantaneous band struct
ure as a function of the drive phases. We show tha
t the average pumping rate is half-integer quantis
ed at the transition with a lifetime that diverges
with the drive frequencies as $\\omega_{1\,2}^{-3
/2}$. The drives also inject energy into the spin\
; we present universal Kibble-Zurek scaling functi
ons for both energy transfer processes in the low
frequency regime. This analysis of the transition
provides an experimentally feasible route to obser
ving the transport signatures of a Dirac point in
a quasiperiodically driven qubit.\n
LOCATION:Theory Library
CONTACT:Mike Gunn
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