Phase Shift and Control in Superconducting Hybrid Structures

Abstract

Taro YAMASHITA†, † †a) , Member SUMMARYThe physics and applications of superconducting phase shifts and their control in superconducting systems are reviewed herein. The operation principle of almost all superconducting devices is related to the superconducting phase, and an efficient control of the phase is crucial for improving the performance and scalability. Furthermore, employing new methods to shift or control the phase may lead to the development of novel superconducting device applications, such as cryogenic memory and quantum computing devices. Recently, as a result of the progress in nanofabrication techniques, superconducting phase shifts utilizing π states have been realized. In this review, following a discussion of the basic physics of phase propagation and shifts in hybrid superconducting structures, interesting phenomena and device applications in phase-shifted superconducting systems are presented. In addition, various possibilities for developing electrically and magnetically controllable 0 and π junctions are presented; these possibilities are expected to be useful for future devices.

Phase controllable Josephson junctions for cryogenic memory

“…These controllable pseudo-spin-valves are part of an increasingly diverse range of Joseph-son junctions with some form of phase control [64]. This phase control has immediate application in multiple areas of superconducting electronics.…”

“…The recent intense interest in topological systems will undoubtedly turn up multiple ways to realize Josephson junctions with controllable phase states [35]. Phase control has immediate application in multiple areas of superconducting electronics [36]. π junctions have applications in both highspeed low-power classical computing [37][38][39][40] and in quantum computing [41][42][43][44].…”

π phase shifter based on NbN-based ferromagnetic Josephson junction on a silicon substrate

“…Ferromagnetic Josephson junctions (superconductor/ferromagnet/superconductor junctions; SFS junctions) have been studied for many years from the perspective of fundamental physics of the interplay between superconductivity and magnetism 1 – 4 . A distinctive feature of SFS junctions is a “π state”, in which the superconducting phase difference is π in the ground state, contrary to conventional Josephson junctions with no phase difference.…”

Magnetism induced by nonlocal spin-entangled electrons in a superconducting spin-valve

“…The interplay between superconductivity and ferromagnetism in hybrid structures has currently attracted considerable attention because of unusual physical phenomena [1][2][3][4] and potential practical applications [5][6][7][8][9]. Various device applications of superconducting hybrid structures have been widely studied in recent years [10][11][12]. Much effort has been devoted to obtaining a better understanding of these phenomena appeared in heterostructures involving superconductor (S) and ferromagnet (F).…”