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CM Seminar - Large?N field theory of confined particles with repulsive interaction

Date and Time: Tuesday, January 21, 2020, 01:30pm - 03:00pm
Location: 330W

The Measurement-Induced Transition in Open Quantum Systems

Michael Gullans
Dept Physics, Princeton U.

Scalable quantum computing fundamentally relies on quantum error correction and fault-tolerance. Sustained efforts in the engineering of controlled quantum systems over the last few decades, combined with parallel advances in high-fidelity quantum measurement, have driven these theoretical concepts into the domain of practical experimental science. In this talk, I will present evidence that the physics of quantum error correction has a wide relevance beyond highly engineered quantum systems and is, in fact, a generic feature of systems interacting with simple, local environments. Using toy models based on random unitary quantum circuit dynamics periodically interspersed with projective measurements, I will describe precise connections that emerge between fundamental notions of quantum error correction, such as the Shannon channel capacity, and the existence of a phase transition in these models as one tunes the measurement rate. I will then show how to define a local order parameter for this transition that is defined by the ability of the system to store one bit of quantum information for exponentially long times. This order parameter points to scalable probes of the transition that are immediately applicable to experiments with noisy-intermediate scale quantum (NISQ) devices such as in trapped ions or superconducting qubits. Studying this class of measurement-driven many-body dynamics may ultimately lead to more efficient realizations of scalable, fault-tolerant quantum computing, as well as deepen our understanding of the transition from quantum to classical physics in many-body systems.

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