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.

Discreteness-induced resonances and ac voltage amplitudes in long one-dimensional Josephson junction arrays

“…This predicts a maximum of about 150 nW from the first harmonic at the first resonance and 46 nW from the second harmonic at the second resonance. These numbers are much smaller than previous estimates [24], and, according to measurements [25,26], are probably more realistic.…”

Self-radiation from arrays of niobium Josephson junctions embedded in the open resonator

“…Many designs have been investigated and extensively reported to improve the impedance coupling of Josephson junctions to the free space. In most cases, broadband antennas such as finline [4], bowtie, spiral [5] or logarithmic-periodic antennas were used [6].…”

Spatially resolved detection of mutually locked Josephson junctions in arrays

“…Phase locking in arrays of Josephson junctions is of broad theoretical 1-5 and experimental [6][7][8][9][10][11][12][13][14][15] interest. From the application point of view the array state where all the junctions oscillate in-phase is the most desired one, because this in-phase state guarantees maximum microwave output power together with minimum linewidth.…”