Investigation of resonant and transient phenomena in Josephson junction flux qubits

TL;DR

This paper provides an analytical and computational study of resonant and transient phenomena in classical Josephson junction flux qubits, linking classical dynamics to quantum-like behaviors observed in experiments.

Contribution

It introduces a theoretical framework connecting single- and multi-junction dynamics and relates classical resonances to quantum phenomena in Josephson systems.

Findings

Analytical and simulation data support classical models of Josephson junction resonances.

Classical models replicate quantum-like Rabi oscillations, Ramsey fringes, and spin echo phenomena.

Off-resonant microwave perturbations influence the Rabi response and resonance behavior.

Abstract

We present an analytical and computational study of resonances and transient responses in a classical Josephson junction system. A theoretical basis for resonances in a superconducting loop with three junctions is presented, outlining both the direct relationship between the dynamics of single- and multi-junction systems, and the direct relationships between observations of the classical counterparts to Rabi oscillations, Ramsey fringes, and spin echo oscillations in this class of systems. We show simulations data along with analytical analyses of the classical model, and the results are related to previously reported experiments conducted on three junction loops. We further investigate the effect of off-resonant microwave perturbations to, e.g., the Rabi-type response of the Josephson system, and we relate this response back to the nonlinear and multi-valued resonance behavior previously reported for a single Josephson junction. The close relationships between single and multi-junction behavior demonstrates the underlying dynamical mechanism for a whole class of classical counterparts to expected quantum mechanical observations in a variety of systems; namely the resonant and transient behavior of a particle in an anharmonic potential well with subsequent escape.