# Theoretical Physics

**19 March 2014**

**Time:**15:00 to 16:00

**Location:**E C Stoner SR 7.70

Clive Emary (Hull)

Quantum feedback control

Feedback control plays an important role in `classical technology' and the bet is that this will continue to be the case as technology moves into the quantum realm. In this talk I will discuss two aspects of my work on the theory of quantum feedback control. Firstly, I will discuss quantum transport, where feedback can be used to modify the conduction and noise properties of quantum nanoscale conductors, as well as produce novel effects such as a nanoelectric Maxwell's daemon and the stabilisation of non-equilibrium pure states. Secondy, I will describe the influence of time-delayed feedback (`Pyragas') control on the Dicke-Hepp-Lieb superradiant quantum phase transition. In this case, feedback dramatically alters the phase diagram of the system and gives rise to an infinite sequence of non-equilibrium phases with fixed points and limit cycles in the symmetry-broken regime.

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