Séminaire du LPTMS : Berislav Buca (Niels Bohr Institute)


11:00 - 12:00

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Eigenoperator thermalization

Berislav Buca (Niels Bohr Institute)

**Online seminar**

I will provide a framework for computing time-averaged dynamics in locally interacting systems in any dimension. It is based on pseudolocal dynamical symmetries generalising pseudolocal charges and unifies seemingly disparate manifestations of quantum non-ergodic dynamics including quantum many-body scars, continuous, discrete and dissipative time crystals, Hilbert space fragmentation, lattice gauge theories, and disorder-free localization. Using the theory two novel types of phase transitions are introduced: 1) The « scarring phase transition » where the order parameter is the locality of the projected local quantities – for certain initial states persistent oscillations are present. 2) The « fragmentation phase transition » for which long-range order is established in an entire phase due to presence of certain non-local strings. Two prototypical, but otherwise mostly intractable, models are solved using the theory: 1) a spin 1 scarred model and 2) the t-J_z model with fragmentation.

Berislav Buca. Unified theory of local quantum many-body dynamics: Eigenoperator thermalization theorems. Phys. Rev. X 13, 031013 (2023).
Benjamin Doyon. Thermalization and pseudolocality in extended quantum systems. Commun. Math. Phys. 351: 155-200 (2017).

Zoom information:
Meeting ID: 962 7757 4790 Passcode: 844783

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