Measurement-based feedback control enables quantum simulation of the chaotic quantum-to-classical transition
April 21, 2020 - Pablo Poggi
In classical mechanics chaos in a dynamical system is related to the unpredictability arising from high sensitivity to the initial configuration. The question of how this behavior, based on the notion of trajectories on phase space, is recovered from the macroscopic limit of the dynamics of quantum systems is a long standing question in theoretical physics. About 20 years ago, in pioneering work, a group of scientists at Los Alamos National Laboratories  investigated the role of quantum measurement as the mechanism enabling the definition of quantum trajectories on phase space, hence allowing the emergence of chaos from quantum dynamics.
Recently a team from CQuIC, led by PhD student Manuel Muñoz and FRHTP postdoc Pablo Poggi, with Project Directors Poul Jessen and Ivan Deutsch, proposed a novel scheme which uses quantum measurement and feedback control to simulate complex dynamics, such as those of chaotic systems . Using the proposed protocol to simulate the dynamics of a quantum kicked top and its mean-field version they showed how the scheme recovers the correct classical chaotic dynamics. The proposed scheme presents a suitable platform to explore the emergence of chaotic “quantum trajectories” featuring the correct classical limit, a problem which is still an open challenge. To strengthen this point the authors studied the proposed scheme in the context of a free space atom-light interface, and showed how in presence of model decoherence and experimental parameters as those in state of the art experiments, the proposed simulation scheme gives access to the correct chaotic classical limit. Thus, this proposal paves the way for the potential experimental observation of the chaotic quantum-to-classical transition.
Given the flexibility of the proposed simulation scheme they expect to see a broad range of applications in the study of quantum simulation of complex systems in the near future.This research was published in Physical Review Letters, and can be accessed in https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.124.11050
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 Manuel H. Muñoz-Arias, Pablo M. Poggi, Poul S. Jessen, and Ivan H. Deutsch, Phys. Rev. Lett. 124, 110503 (2020)