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Randomness is an essential tool in many disciplines of modern sciences, such as cryptography, black hole physics, random matrix theory, and Monte Carlo sampling. In quantum systems, random operations can be obtained via random circuits thanks to socalled qdesigns and play a central role in condensedmatter physics and in the fast scrambling conjecture for black holes. Here, we consider a more physically motivated way of generating random evolutions by exploiting the manybody dynamics of a quantum system driven with stochastic external pulses. We combine techniques from quantum control, open quantum systems, and exactly solvable models (via the Bethe ansatz) to generate Haaruniform random operations in driven manybody systems. We show that any fully controllable system converges to a unitary
qdesign in the longtime limit. Moreover, we study the convergence time of a driven spin chain by mapping its random evolution into a semigroup with an integrable Liouvillian and finding its gap. Remarkably, we find via Betheansatz techniques that the gap is independent of q. We use meanfield techniques to argue that this property may be typical for other controllable systems, although we explicitly construct counterexamples via symmetrybreaking arguments to show that this is not always the case. Our findings open up new physical methods to transform classical randomness into quantum randomness, via a combination of quantum manybody dynamics and random driving.
qdesign in the longtime limit. Moreover, we study the convergence time of a driven spin chain by mapping its random evolution into a semigroup with an integrable Liouvillian and finding its gap. Remarkably, we find via Betheansatz techniques that the gap is independent of q. We use meanfield techniques to argue that this property may be typical for other controllable systems, although we explicitly construct counterexamples via symmetrybreaking arguments to show that this is not always the case. Our findings open up new physical methods to transform classical randomness into quantum randomness, via a combination of quantum manybody dynamics and random driving.
Iaith wreiddiol  Saesneg 

Rhif yr erthygl  041015 
Nifer y tudalennau  24 
Cyfnodolyn  Physical Review X 
Cyfrol  7 
Dynodwyr Gwrthrych Digidol (DOIs)  
Statws  Cyhoeddwyd  20 Hyd 2017 
Ôl bys
Gweld gwybodaeth am bynciau ymchwil 'Driven Quantum Dynamics: Will It Blend?'. Gyda’i gilydd, maen nhw’n ffurfio ôl bys unigryw.Proffiliau

Daniel Burgarth
 Cyfadran Busnes a’r Gwyddorau Ffisegol, Mathemateg  Honorary Appointment
Unigolyn: Arall
Prosiectau
 1 Wedi Gorffen

Control characterisation of noisy quantum devices
Engineering & Physical Sciences Research Council
01 Meh 2015 → 30 Medi 2016
Prosiect: Ymchwil a ariannwyd yn allanol