The voltage oscillations which occur in an ideally current-biased Josephson junction, were proposed to make a current standard for metrology. We demonstrate similar oscillations in a more complex Josephson circuit derived from the Cooper pair box: the quantronium. When a constant current I is injected in the gate capacitor of this device, oscillations develop at the frequency fB=I/2e, with e the electron charge. We detect these oscillations through the sidebands induced at multiples of fB in the spectrum of a microwave signal reflected on the circuit, up to currents I exceeding 100 pA. We discuss the potential interest of this current to frequency conversion experiment for metrology.
@article{arxiv.0709.4097,
title = {Current to frequency conversion in a Josephson circuit},
author = {F. Nguyen and N. Boulant and G. Ithier and P. Bertet and H. Pothier and D. Vion and D. Esteve},
journal= {arXiv preprint arXiv:0709.4097},
year = {2007}
}