Séminaire du LPTMS : Marko Žnidarič (Ljubljana University)

Non-Hermitian phantoms

Marko Žnidarič (University of Ljubljana)

Hybrid seminar: onsite + zoom.

https://cnrs.zoom.us/j/96002697257?pwd=VXViU0EvMWJDa0FFMXhXbE5qMjdsZz09
Meeting ID: 960 0269 7257
Passcode: qi8a9S

Describing full unitary dynamics of a many-body system is difficult and also unpractical. Focusing on a coarse-grained dynamics, or few select smooth observables, often results in a more compact non-unitary evolution. Studying bipartite entanglement dynamics in random circuits one can derive a Markovian transfer matrix description that harbors rather intriguing many-body non-Hermitian physics. The speed of generating entanglement is not given by the 2nd largest eigenvalue of the transfer matrix, but rather by a phantom eigenvalue that is not in the spectrum of any finite transfer matrix. Resolution of this seeming paradox will involve a spectrum that is completely discontinuous in the thermodynamic limit. When dealing with finite non-Hermitian matrices it can turn out that being exact is actually wrong, while being slightly wrong is correct.

Date/Time : 21/06/2022 - 11:00 - 12:00

Location : Salle des séminaires du FAST et du LPTMS, bâtiment Pascal n°530