Nondestructive readout for a superconducting flux qubit

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  • 21 November 2003
Abstract
We have implemented a nondestructive method for the readout of a flux qubit. The detection is based on the measurement of the Josephson inductance of a DC superconducting quantum interference device (DC-SQUID) inductively coupled to the qubit. The SQUID is included in a resonant circuit, allowing for high flux sensitivity. The measurement strength can be tuned with the amplitude of the RF-signal used to drive the resonant circuit. Using this method, we measured the spectroscopy of a persistent current qubit and we obtained relaxation times of the order of 80 $\mu s$.