# Tunneling vortex dynamics in linearly coupled Bose-Hubbard rings

## TL;DR

This paper investigates the quantum tunneling and dynamics of vortices in coupled Bose-Hubbard rings, revealing coherent vortex transfer, Josephson-like effects, and the impact of interactions on system behavior.

## Contribution

It provides a detailed analysis of vortex tunneling dynamics in coupled Bose-Hubbard rings, highlighting regimes of coherent oscillations and flux-qubit-like behavior.

## Key findings

- Vortex tunneling exhibits coherent, oscillating dynamics at low interactions.
- Persistent currents switch resemble flux-qubit features.
- Strong interactions suppress chiral currents and cause fragmentation.

## Abstract

The quantum dynamics of population-balanced fractional vortices and population-imbalanced vortices in an effective two-state bosonic system, made of two coupled discrete circuits with few sites, is addressed within the Bose-Hubbard model. % We show that for low on-site interaction, the tunneling of quantized vortices between the rings performs a coherent, oscillating dynamics connecting current states with chiral symmetry. The vortex-flux transfer dually follows the usual sinusoidal particle current of the Josephson effect, in good agreement with a mean-field approximation. Within such regime, the switch of persistent currents in the rings resembles flux-qubit features, and is feasible to experimental realization. On the contrary, strong interatomic interactions suppress the chiral current and lead the system into fragmented condensation.