As the last talk of the year, we have Clemens Gneiting, from the Quantum Optics and Statistics group of Freiburg university. I have a special relation with this group, as I was postdoc there for about 3 years with Andreas Buchleitner. Great physics, loads of fun!
Clemens is an expert on modular variables, specially in connection with violations of Bell inequalities using continuous-variables systems. But of course he has other research lines, and this time he’ll tell us about optimal coherent control of noisy quantum systems. A subject that will definitely resonate with both experimentalists and theorists. So please be sure to show up for this talk! See info below.
Speaker: Clemens Gneiting (Freiburg Univesity)
Title: Prospects of coherent control in the presence of dissipation
Coordinates: room 601D, CBPF. 11.12, 16:00h
Abstract: Genuine quantum features such as entanglement or coherence are resources as precious as fragile, and their uncovering usually requires strong efforts in isolating and controlling quantum systems. Without thorough measures, decoherence efficiently shields the quantum world from our access and hides it behind its classical guise. While there has been unprecedented progress in the quantum control of various model systems, e.g. ions, quantum dots, or cold atoms, it is impossible to completely decouple these systems from their environment and thus to fully suppress the detrimental effect of decoherence. Standard optimal control techniques therefore focus on accessing quantum features in the transient regime, and the exploration and exploitation of quantum properties is consequently confined to a finite, generically short time window. We investigate to what extent coherent Hamiltonian control can enduringly counteract the detrimental effect of decoherence. Explicitly, we determine Hamiltonians that optimally uphold desired control objectives (e.g., coherence, entanglement, or fidelity w.r.t. a target state) in the presence of dissipation. As we show, our method is applicable to both static and periodically time-dependent Hamiltonians. Finally, we also discuss modifications of the scheme due to continuous measurement and feedback.