Quantum superpositions of clockwise and counterclockwise supercurrent states in the dynamics of a rf-SQUID exposed to a quantized electromagnetic field

TL;DR

This paper theoretically investigates the dynamics of an rf-SQUID coupled to a quantized electromagnetic field, demonstrating control over entanglement and the generation of superpositions of macroscopic current states.

Contribution

It introduces a method to generate and control quantum superpositions of macroscopic current states in an rf-SQUID using a quantized electromagnetic field.

Findings

Demonstrates oscillatory behavior with multiple Rabi frequencies.

Shows control over entanglement dynamics and periodic evolution.

Proposes feasible experimental implementation.

Abstract

The dynamical behavior of a superconducting quantum interference device (a rf-SQUID) irradiated by a single mode quantized electromagnetic field is theoretically investigated. Treating the SQUID as a flux qubit, we analyze the dynamics of the combined system within the low lying energy Hilbert subspace both in the asymmetric and in the symmetric SQUID potential configurations. We show that the temporal evolution of the system is dominated by an oscillatory behavior characterized by more than one, generally speaking, incommensurable Rabi frequencies whose expressions are explicitly given. We find that the external parameters may fixed in such a way to realize a control on the dynamical replay of the total system which, for instance, may be forced to exhibit a periodic evolution accompanied by the occurrence of an oscillatory disappearance of entanglement between the two subsystems. We demonstrate the possibility of generating quantum maximally entangled superpositions of the two macroscopically distinguishable states describing clockwise and counterclockwise supercurrents in the loop. The experimental feasibility of our proposal is briefly discussed.