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Time delayed control of excited state quantum phase transitions in the Lipkin–Meshkov–Glick model

Kopylov, Wassilij; Brandes, Tobias

FG Computergestützte Materialphysik

We theoretically investigate the role of dissipation in excited state quantum phase transitions (ESQPT) within the Lipkin–Meshkov–Glick model. Signatures of the ESQPT are directly visible in the complex spectrum of an effective Hamiltonian, whereas they get smeared out in the time-dependence of system observables. In the latter case, we show how delayed feedback control can be used to restore the visibility of the ESQPT signals.