Bonn 2025 – wissenschaftliches Programm
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Q: Fachverband Quantenoptik und Photonik
Q 72: Ultra-cold Atoms, Ions and BEC V (joint session A/Q)
Q 72.5: Vortrag
Freitag, 14. März 2025, 12:00–12:15, GrHS Mathe
Probing many-body quantum dynamics using subsystem Loschmidt echos — •Simon Karch1,2,3, Alexander Impertro1,2,3, SeungJung Huh1,2,3, Irene Prieto Rodriguez1,2,3, Souvik Bandyopadhyay4, Zheng-Hang Sun5, Wolfgang Ketterle6, Markus Heyl5, Anatoli Polkovnikov4, Immanuel Bloch1,2,3, and Monika Aidelsburger1,2,3 — 1Fakultät für Physik, LMU, Munich, Germany — 2Max-Planck-Institut für Quantenoptik, Garching, Germany — 3MCQST, Munich, Germany — 4Department of Physics, Boston University, Boston, MA, USA — 5Institute of Physics, University of Augsburg, Augsburg, Germany — 6Department of Physics, MIT, Cambridge, MA, USA
The Loschmidt echo - the probability of a quantum many-body system to return to its initial state following a dynamical evolution - is a key quantity in statistical physics. However, it is typically exponentially small, posing significant challenges for experimental measurement. We introduce the subsystem Loschmidt echo, a quasi-local approximation that enables extrapolation to the full-system Loschmidt echo, even in very large systems. Utilizing quantum gas microscopy, we investigate both short- and long-time dynamics of the subsystem Loschmidt echo, demonstrating its ability to capture key features of the Loschmidt echo in a many-body quantum system. In the short-time regime, we use it to observe dynamical quantum phase transitions, while in the long-time regime, our method allows us to measure the inverse participation ratio (IPR), providing a quantitative measure of the dimension of accessible Hilbert space in ergodic and fragmented systems.
Keywords: quantum simulation; statistical physics; optical lattices; chaos; fragmentation