David Pekker, Ph.D. Assistant Professor, Department of Physics and Astronomy, University of Pittsburgh

Protecting quantum information with disorder

Abstract

Equilibration and thermalization are fundamental ingredients in our description of physical, chemical and biological systems. These processes allow us to make descriptions base don statistical ensembles, in or close to equilibrium, thus resolving the paradox of the ‘arrow of time.’ In this proposal, we will address the question of how the ‘arrow of time’ can be broken in a generic interacting quantum many-particle systems with disorder.

A useful way to think about the arrow of time and thermalization has been offered by the field of quantum information theory: the irreversibility of the evolution is connected to the generation of entanglement between subparts of the system undergoing equilibrium. Until recently, it has been thought that interactions in generic quantum systems would always drive this type of entanglement growth, and hence lead to thermalization. In the recently discovered phase of matter – the many-body localized phase – this paradigm is broken down by the interplay of disorder and interactions.

The goals of the proposed research is the combine the tools of quantum information theory and of condensed matter physics to construct a detailed theory of many-body localized systems, their dynamics, and the quantum information contained within these systems. In the process, I hope to learn how to use disorder as a resource for attached the central questions of the two subject areas: condensed matter physics and quantum computation. For condensed matter physics: how to describe and control the dynamics of many-body quantum systems? For quantum computation: how to build qubits that do not become entangled with their environment, even at high temperatures?

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