Quantized Josephson phase battery

Abstract

A ferromagnetic Josephson junction with a spin-flipper (magnetic impurity) sandwiched in-between acts as a phase battery that can store quantized amounts of superconducting phase difference ϕ0 in the ground state of the junction. Moreover, for such ϕ0-Josephson junction anomalous Josephson current appears at zero phase difference. We study the properties of this quantum spin-flip scattering induced anomalous Josephson current, especially its tun-ability via misorientation angle between two Ferromagnets.

Geometry controlled superconducting diode and anomalous Josephson effect triggered by the topological phase transition in curved proximitized nanowires

“…The superconducting diode effect enables directional charge transport without energy loss at low temperatures and has been recently observed in artificial superlattices Nb/Va/Ta 51 . The possibility of the superconducting diode effect has been also predicted in a variety of Josephson systems including Josephson junctions through the helical edge states of a quantum spin-Hall insulator 37 , ferromagnetic Josephson junctions with spin-active interfaces 35,40 , and Josephson junctions through a straight multi-channel semiconducting nanowire with strong spin-orbit coupling in the presence of magnetic field 36 . Note that according to previous theoretical works the appearance of nonreciprocal transport in junctions through straight semiconducting nanowires requires multi-channel regime.…”

“…Such behavior stems from the geometry-induced switching of the direction of the spin-orbit field which, in turn, leads to the appearance of the anomalous phase shift in the ground state of such junctions. Note that the systems exhibiting the anomalous Josephson effect are in the focus of current research work [34][35][36][37][38][39][40][41][42][43] due to the possibility of their use as phase batteries. The phase battery is known to be an important device of superconducting electronics which provides a constant phase shift between two superconductors in a quantum circuit 44 .…”

Universal Josephson diode effect

“…Supercurrent nonreciprocity has also been observed in a number of experiments on Josephson junctions [4][5][6][7][8], often referred to as Josephson diode effect (JDE). While several theoretical proposals based on various physical mechanisms have been put forward [16][17][18][19][20][21][22][23][24][25], a clear understanding of the microscopic origin of the Josephson diode effect observed in experiments is still lacking. Very recently, an experiment [7] showed simultaneous occurrence of the Josephson diode effect and finite Cooper pair momentum in a superconductor-normal-superconductor junction where two niobium electrodes were coupled by FIG.…”

“…It arises from and provides a measure of the Doppler shift of quasiparticle energy due to Cooper pair momentum. It does not rely on scattering between multiple conduction channels [16][17][18][19][20], layered magnetic structures [22], curved geometry of a nanowire [23], or doped Mott insulator region at the interface [24].…”

Anomalous Josephson Effect in Topological Insulator-Based Josephson Trijunction

“…The anomalous phase shift could cause spin-galvanic effect, also known as inverse Edelstein effect [10,11]. Such a magneto-electric effect might be useful in future superconducting electronics and spintronics [12], such as to drive quantum phase batteries [13], to form superconducting quantum memories [14,15], or to induce topological superconductivity [16][17][18][19], etc.…”