# Quantum Computation and Information Seminar

## 25/03/2015, 10:00 — 11:00 — Room P3.10, Mathematics Building Abolfazl Bayat, University College London

### Universal single-frequency oscillation of the entanglement spectrum after a local quench

Long-lived single-frequency oscillations in the local non-equilibrium dynamics of a quantum many-body system is an exceptional phenomenon. In fact, till now, it has never been observed, nor predicted, for the physically relevant case where a system is prepared to be quenched from one quantum phase to another. Here we show how the quench dynamics of the entanglement spectrum may reveal the emergence of such oscillations in a correlated quantum system with Kondo impurities. The oscillations we find are characterized by a single frequency which is proportional to the Kondo temperature of the system. The frequency is universal, being independent of the amount of energy released by the local quench, and scales as $1/N$ for $N$ being the size of the system. Importantly, the universal frequency manifests itself also in local observables, such as the spin-spin correlation function of the impurities.

Supported by: Phys-Info (IT), SQIG (IT), CeFEMA and CAMGSD, with funding from FCT, FEDER and EU FP7, specifically through the Doctoral Programme in the Physics and Mathematics of Information (DP-PMI), FCT strategic projects PEst-OE/EEI/LA0008/2013 and UID/EEA/50008/2013, IT project QuSim, project CRUP-CPU CQVibes, the FP7 Coordination Action QUTE-EUROPE (600788), and the FP7 projects Landauer (GA 318287) and PAPETS (323901).