Bloch Oscillations in a Josephson Circuit
Abstract
Bloch oscillations predicted to occur in current-biased single Josephson junctions have eluded direct observation up to now. Here, we demonstrate similar Bloch oscillations in a slightly richer Josephson circuit, the quantronium. The quantronium is a Bloch transistor with two small junctions in series, defining an island, in parallel with a larger junction. In the ground state, the microwave impedance of the device is modulated periodically with the charge on the gate capacitor coupled to the transistor island. When a current flows across this capacitor, the impedance modulation occurs at the Bloch frequency, which yields Bloch sidebands in the spectrum of a reflected continuous microwave signal. We have measured this spectrum, and compared it to predictions based on a simple model for the circuit. We discuss the interest of this experiment for metrology and for mesoscopic physics.
Cite
@article{arxiv.cond-mat/0605061,
title = {Bloch Oscillations in a Josephson Circuit},
author = {N. Boulant and G. Ithier and F. Nguyen and P. Bertet and H. Pothier and D. Vion and C. Urbina and D. Esteve},
journal= {arXiv preprint arXiv:cond-mat/0605061},
year = {2007}
}