Séminaire du LPTMS : Alberto Biella (LPTMS)

Measurement-induced entanglement phase transitions and the Quantum Zeno Effect

Alberto Biella (LPTMS)

Online seminar — ZOOM Meeting ID: 918 3216 1661 — Password: Ask L. Mazza or D. Petrov —

It is well known that by repeatedly measuring a quantum system it is possible to completely freeze its dynamics into a well defined state, a signature of the Quantum Zeno Effect. In my talk I will discuss how, for a many-body system evolving under competing unitary evolution and variable-strength measurements, the onset of the Zeno effect takes the form of a sharp phase transition [1]. Using the Quantum Ising chain with continuous monitoring of the transverse magnetization as paradigmatic example, we show that for weak measurements the entanglement produced by the unitary dynamics remains protected, while only above a certain threshold the system is sharply brought into an uncorrelated Zeno subspace. Furthermore, we show that this transition is invisible to the average dynamics, but encoded in the rare fluctuations of the stochastic measurement process. Finally we trace an intriguing connection between the onset of the Zeno effect and the subradiance transition of the associated non-Hermitian Hamiltonian.

[1] AB, M. Schirò, arXiv:2011.11620

Date/Time : 09/02/2021 - 11:00 - 12:00

Location : LPTMS (100% online seminar)

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