We propose to use the quantum properties of a superconducting flux qubit in the construction of a magnetometer with quantum limited sensitivity. The main advantage of a flux qubit is that its noise is rather low, and its transfer functions relative to the measured flux can be made to be about 10mV/Φ0, which is an order of magnitude more than the best value for a conventional SQUID magnetometer. We analyze here the voltage-to-flux, the phase-to-flux transfer functions and the main noise sources. We show that the experimental characteristics of a flux qubit, obtained in recent experiments, allow the use of a flux qubit as magnetometer with energy resolution close to the Planck constant.
@article{arxiv.cond-mat/0608416,
title = {Flux qubit as a sensor for a magnetometer with quantum limited sensitivity},
author = {E. Il'ichev and Ya. S. Greenberg},
journal= {arXiv preprint arXiv:cond-mat/0608416},
year = {2007}
}