A tunable macroscopic quantum system based on two fractional vortices

TL;DR

This paper introduces a controllable macroscopic quantum system using two fractional vortices in a Josephson junction, enabling quantum oscillations and state preparation through tunable discontinuities.

Contribution

It presents a novel method to realize and control a macroscopic quantum system with fractional vortices, mapping its dynamics to a double-well potential for quantum regime exploration.

Findings

Coherent quantum oscillations can be achieved in the system.

Tuning iscontinuities controls the double-well potential parameters.

Experimental realization is feasible with current technology.

Abstract

We propose a tunable macroscopic quantum system based on two fractional vortices. Our analysis shows that two coupled fractional vortices pinned at two artificially created \kappa\ discontinuities of the Josephson phase in a long Josephson junction can reach the quantum regime where coherent quantum oscillations arise. For this purpose we map the dynamics of this system to that of a single particle in a double-well potential. By tuning the \kappa\ discontinuities with injector currents we are able to control the parameters of the effective double-well potential as well as to prepare a desired state of the fractional vortex molecule. The values of the parameters derived from this model suggest that an experimental realisation of this tunable macroscopic quantum system is possible with today's technology.