Emission linewidth measurements of two-dimensional array Josephson oscillators

Abstract

We have coupled emission from 10×10 arrays of Josephson junctions at 4 K to a room-temperature mixer through a fin-line antenna and a WR-12 waveguide. A single voltage-tunable peak was detected in the frequency range from 53 to 230 GHz. A stripline resonance in the antenna reduced the array’s dynamic resistance and thereby the emission linewidth to as low as 10 kHz. We extract an effective noise temperature of 14 K from the linewidth data.