Time-resolved measurement of a charge qubit |
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| Georg Reuther | |
| Universität 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 driving signal. 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 demonstrate this result by means of a charge qubit realized with a Cooper-pair box, where we focus on monitoring coherent oscillations and a Landau-Zener transition. |