Coherent amplification of radiation from two phase-locked Josephson junction arrays

• Published in: Beilstein journal of nanotechnology Vol. 13; pp. 1445 - 1457
• Main Authors: Galin, Mikhail A, Krasnov, Vladimir M, Shereshevsky, Ilya A, Vdovicheva, Nadezhda K, Kurin, Vladislav V
• Format: Journal Article
• Language: English
• Published: Germany Beilstein-Institut zur Föerderung der Chemischen Wissenschaften 2022
• Subjects: Arrays; coherent radiation; Electrodes; Electromagnetic fields; Electromagnetic interactions; Interference; Josephson junction arrays; Josephson junctions; Linear arrays; Locking; numerical modelling; Numerical models; Oscillators; Radiation; single-strip line; Substrates; Synchronism; synchronization; numerical modelling; coherent radiation; synchronization; Josephson junction arrays; single-strip line
• ISSN: 2190-4286; 2190-4286
• DOI: 10.3762/bjnano.13.119

We analyze experimentally and theoretically mutual phase locking and electromagnetic interaction between two linear arrays with a large number of Josephson junctions. Arrays with different separation, either on the same chip or on two separate substrates are studied. We observe a large coherent gain, up to a factor of three, of emitted power from two simultaneously biased arrays, compared to the sum of powers from two individually biased arrays. The phenomenon is attributed to the phase locking of junctions in different arrays via a common electromagnetic field. Remarkably, the gain can exceed the factor of two expected for a simple constructive interference of two oscillators. The larger gain is explained by an additional consequence of mutual interaction between two large arrays. Mutual phase locking of large arrays does not only result in constructive interference outside the arrays, but also improved synchronization of junctions inside each array. Our conclusion is supported by numerical modelling.