Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 62: Nonequilibrium Quantum Many-Body Systems II (joint session TT/DY)

TT 62.8: Talk

Wednesday, March 14, 2018, 17:15–17:30, H 3010

Impurity induced quench dynamics in shallow Fermi seas: an analytic treatment — •Conor Jackson and Bernd Braunecker — University of St Andrews, St Andrews, United Kingdom

We investigate the Loschmidt echo for a system of free fermions after the introduction of a local quench impurity, taking account of the finite band depth. For a system with a large bandwidth, the sudden introduction of an impurity leads to the well-known Fermi-Edge Singularity and a characteristic power law decay in the Loschmidt echo in the long time limit. We examine analytically the effect of the finite band bottom at intermediate time scales, using a Riemann-Hilbert approach to evaluate the functional determinants induced by the fermionic statistics. On these time scales we find disruption of the entire Fermi sea, rather than simply the surface shakeup which leads to the standard result, and we can provide an analytic explanation of previous numerical results.