Quantum Information Scrambling in Many-body Localized Systems

Project: Research

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Quantum technology, such as quantum computation, quantum cryptography, and quantum simulation, is likely to become one of the driving force for the development of human society in future. Such technologies have enormous potentials because they can achieve goals far beyond today's classical computer power. Recently, Google has announced that it has reached the first milestone towards such quantum supremacy. As a result, competitions on building infrastructures for future quantum technology has become increasingly important. One crucial step towards the realization of quantum simulation and quantum computation is the ability to store and coherently manipulate quantum information in an isolated quantum system. However, this is generally not an easy task. Conventionally it is believed that a generic quantum many-body system will eventually reach thermal equilibrium under its own dynamics. As a result, the initial state memory will quickly get lost to nonlocal degrees of freedom, and hence can no longer be recovered by a local measurement. What remains are the fluctuations of some conserved quantities, whose dynamics is purely classical. In fact, this notion is so widely accepted that many textbooks on statistical mechanics are built on the ergodicity hypothesis. Recently, however, people have realized that this classical fate is not inevitable. In particular, an isolated interacting many-body quantum system can escape thermalization if strong quenched disorders are present. This phenomenon, now known as many-body localization (MBL), has attracted enormous interest in the research community because all eigenstates in the energy spectrum break ergodicity. Thus, quantum information stored in a generic initial state may be retained for an extended period of time, which presents a great potential for quantum information storage and manipulation. In this work, we will study quantum information scrambling in a many-body localized system. Specifically, four main research tasks are outlined in this proposal: (1) Understanding quantum information scrambling in a many-body localized system; (2) Behavior of quantum information scrambling near MBL-thermal transitions; (3) The application of machine-learning techniques in quantum information scrambling; (4) Quantum information scrambling in generic out-of-equilibrium systems. This study aims at uncovering how the quantum information stored in the initial states spreads out in an MBL system, and the results will help us better understand how to utilize a generic many-body system for quantum information storage and manipulation purposes. 


Project number9043180
Grant typeGRF
Effective start/end date1/01/22 → …