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Special Institute for Condensed Matter Theory Seminar: Thermodynamics and order beyond equilibrium -- from eigenstate thermalisation to time crystals

Event Type
The Institute for Condensed Matter Theory
MRL 280
Apr 12, 2022   12:00 pm  
Prof. Dr. Roderich Moessner, Max Planck Institute for the Physics of Complex Systems
Originating Calendar
Physics - Institute for Condensed Matter Theory Seminar

The field of thermodynamics is one of the crown jewels of classical physics. Thanks to the advent of experiments in cold atomic systems with long coherence times, our understanding of the connection of thermodynamics to quantum statistical mechanics has seen remarkable progress.

Extending these ideas and concepts to the non-equilibrium setting is a challenging topic, in itself of perennial interest. Here, we present perhaps the simplest non-equilibrium class of quantum problems, namely Floquet systems, i.e. systems whose Hamiltonians depend on time periodically, H(t + T) = H(t). For these, there is no energy conservation, and hence not even a natural concept of temperature.

We find that certain structures from equilibrium thermodynamics are lost, while entirely new non-equilibrium phenomena can arise, including a spectacular spatiotemporal `time-crystalline' form of order, recently observed experimentally on google AI's sycamore NISQ platform.

References: for an introductory overview, see Nature Physics 13, 424–428 (2017). For an in-depth review, see arxiv:1910.10745 . NISQ experiment: Nature 601, 531 (2022).

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