Josephson Junction Array for Voltage Metrology: Microwave Enhancement by Coupled Self-Generations in Series Array

전압 측정표준용 조셉슨 접합 어레이: 직렬 어레이에서 상호 결합된 자체발진의 마이크로파 증진

Coupling of non-linear oscillators have long been an interesting problem for physicists. The coupling phenomena have been frequently observed in Josephson junction series array, which have been used for Josephson voltage standard. Interestingly pronounced self-generation effect has been found during recent development of Josephson arrays for programmable Josephson voltage standard. But the coupling effect between the self-generations is not fully understood yet. We present harmonically approximated analytical solutions for coupled self-generations in the Josephson arrays, i.e., Superconductor-Insulator-Normal metal-Insulator-Superconductor (SINIS) array, externally shunted Superconductor-Insulator-Supercondctor (es-SIS) array, Superconductor-Normal metal-Superconductor (SNS) array. We find that the coupling between the self-generated Josephson oscillations through microwave transmission line plays critical role in microwave property of the Josephson array.