Instanteous feedback control of quantum transport
Dr. Clive Emary:
I will survey some new results in the feedback control in quantum transport. We have extensively developed the theory of instantaneous control of Markovian systems in which information obtained from measurements of the full counting statistics is fed back into the transport device. We have shown how this type of feedback can be used for quantum state purification and control of. e.g. a charge qubit. Furthermore, these ideas can even be extended to the stabilisation of non-equillibrium pure states. Another interesting application is the realisation of a mesoscopic Maxwell's demon which employs feedback to move electrons against either voltage or temperature gradients. We have studied the occurrence of feedback catastrophes and the influence of feedback on mesoscopic fluctuation theorems. I will also discuss some work on the Dicke model, a paradigm of collective behaviour in atom-photon systems, with an eye towards a theory of control of quantum phase transitions.