Synchronization of Large Josephson-Junction Arrays by Traveling Electromagnetic Waves

Abstract

Josephson junctions can be used to generate terahertz radiation, but achieving high emission power requires phase locking of many junctions in an array. The conventional cavity-resonance (standing-wave) mechanism of phase locking an array becomes ineffective when the extent of the array becomes larger than the wavelength. This study of coherent superradiant emission from such large arrays of Nb/NbSi/Nb Josephson junctions finds evidence for another, nonresonant mechanism of synchronization, via a traveling wave. That mechanism seems to offer the possibility of phase locking very large arrays of coupled oscillators, of any type.