Mutually Synchronized Macroscopic Josephson Oscillations Demonstrated by Polarization Analysis of Superconducting Terahertz Emitters

Despite its potential for $e.g.$ medical imaging, wireless communication, and ultrasensitive analysis of biological materials, the terahertz frequency range of light cannot be suitably utilized without practical solid-state sources. A naturally formed stack of superconducting junctions emits terahertz radiation, owing to synchronization of macroscopic wave functions, and the authors propose a means to manipulate that synchronization, which is the most promising way to attain a versatile superconducting terahertz source. Their findings also give insight into the quantum physics of entangled photons emitted from superconductors.