Dresden 2009 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 44: Transport: Quantum Coherence and Quantum Information

TT 44.7: Talk

Thursday, March 26, 2009, 15:45–16:00, HSZ 304

Time-Resolved Measurement of a Charge Qubit — •Georg M. Reuther, David Zueco, Peter Hänggi, and Sigmund Kohler — Institut für Physik, Universität Augsburg, Universitätsstr. 1, 86159 Augsburg

We propose a scheme for monitoring coherent quantum dynamics with good time-resolution and low backaction. It relies on the response of the considered quantum system to a high-frequency ac drive. We find that the phase of the outgoing signal, which can directly be measured in an experiment with lock-in technique, is proportional to the expectation value of a particular system observable. We present explicit results for a charge qubit realized with a Cooper-pair box, where we focus on monitoring coherent oscillations and Landau-Zener transitions.