Generation of coherent tunable Josephson radiation at microwave frequencies with narrowed linewidth

Abstract

Coherent tunable microwave radiation (2–18 GHz) has been observed from two microbridge Josephson junctions coupled by a shunt resistor. The coherent power (∼4×10−12 W) is nearly four times the power emitted by a single junction. The linewidth of the radiation in the coherent state is one-half that from the individual microbridges.