Possible existence of field‐induced Josephson junctions

Abstract

We demonstrate the possible existence of a new class of superconducting Josephson junctions (JJs) named field-induced Josephson junctions (FIJJs). One representative is a junction made by placing a ferromagnetic strip on the top of a superconducting strip, which we study in this work. We obtain a possible transition between one regime of an FIJJ, which is the quasi-tunneling weak link Josephson junction (similar in certain aspects to an S-F-S Josephson junction, but with different boundary conditions), and the second regime of an FIJJ, which is the weak link constriction (two superconductors connected by a narrow superconducting link) as a function of the thickness of the superconducting strip, magnitude of magnetization, and temperature. We use the generalized Ginzburg-Landau (GL) equations derived from the extended Hubbard model in order to determine some properties of the new class of Josephson junction. In this paper, we perform the computation for a first type of superconductor, although both types of superconductor can be used to create an FIJJ. Further directions of studies of the indicated class of Josephson junction are also described.

From two types of electrostatic position-dependent semiconductor qubits to quantum universal gates and hybrid semiconductor-superconducting quantum computer

“…In certain conditions as in case of semiconductor or superconducting nanowires PDEs can be reduced to ODEs. Detailed study of PDEs requires the usage of Trotter matrices in 2 dimensions or requires the use of relaxation method as pointed in 14,15 and is also beyond the scope of this work. Despite simplistic assumptions neglecting spin effects and treating system in one dimensional way the presented methodology can be used for quantum circuits and system of large integration under assumption of possible reduction from PDEs to ODEs.…”

“…It is thus recommendable to trace methodological steps presented in. 14 The mentioned issues are the subject of future work.…”

Relaxation method in description of RAM memory cell in RSFQ computer

“…Otherwise, additional magnetic flux will be generated, which would disturb the proper operation of the neighbouring cells. If the ferromagnetic strips are placed on the superconductor with an insulating barrier in between, it is possible to model such a system using the concept of a field induced Josephson junction as introduced by Pomorski et al (2016), Pomorski (2015); Pomorski and Prokopow (2012), Clinton and Johnson (1999); and Gomez and Maeda (2007), as depicted in Figures 2 and 8. However, it is worth noting that the physics of field-induced Josephson junctions (FIJJ) are quite rich as given by Carapella et al (2016) and many others.…”

“…The stray field from the ferromagnetic element was used to locally diminish the superconducting order parameter (SCOP). Later, this concept was generalized by Gomez and Maeda (2007) and described theoretically by Pomorski and Prokopow (2012). The ferromagnetic strip was placed directly on top of the superconducting strip.…”

“…We will consider a superconducting quasi-one dimensional cable, so the principle of electric current conservation is preserved. Hence: where y = 0 and c 1 is a constant, as presented in Pomorski et al (2016), along the superconducting cable of small thickness. Essentially, in case of temperatures close to a critical superconducting temperature T c , we can use a quasi-one dimensional Ginzburg–Landau equation for a complex scalar field in the form: where α < 0 and β > 0 stand [standard parameters of Ginzburg-Landau (GL) theory] for the superconducting state.…”