CM Seminar at ICTP - Friday 5 February at 11.30 - Luigi Stasi Lecture Hall

[Condensed Matter Section]

ICTP Special Seminar in Condensed Matter and Statistical Physics
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FRIDAY 5 FEBRUARYat 11:30 hrs.

Luigi Stasi Seminar Room, first floor, ICTP Leonardo Building


Felix BINDER
Clarendon Laboratory, Dept. of Physics, University of Oxford, U.K.


"Quantum Batteries, Quantum Speed Limits, and Powerful Unitary Driving"

The speed of quantum evolution is bounded by the quantum speed limits
(QSLs) which may be formulated in terms of properties of the driving
Hamiltonian (in particular, its variance).  QSLs will be introduced and
used to motivate the study of quantum power. Defining the notion of a
quantum battery the question of achieving high driving power is then
phrased in terms of powerful battery charging. For the simplest possible
model of a quantum battery -- a work qubit (or 'wit') -- an optimal
charging protocol may be derived. Extending the analysis to an array of N
qubits, it is demonstrated that an N-fold advantage in power per wit can
be achieved when global operations are permitted (rather than a
restriction to local operations and classical communication (LOCC)).
Interestingly, this quantum advantage for power holds even when, with
cyclic operation in mind, initial and final states are required to be
separable.The exemplary analytic argument for this quantum advantage in
the charging power is explained by a geometric argument on the one side
and a re-consideration of the applicable quantum speed limit on the other.