Equilibrium and dynamical quantum phase transitions in dipolar atomic Josephson junctions

TL;DR

This paper explores how dipolar interactions in atomic Josephson junctions influence equilibrium phases and dynamical quantum phase transitions, revealing new effects on ground states and self-trapping phenomena.

Contribution

It introduces the impact of pair tunneling on phase diagrams and quantum phase transitions in dipolar bosonic systems, combining mean-field and exact quantum analyses.

Findings

Pair tunneling induces ground-state parity modulations.

Significant reshaping of the phase diagram and critical points.

Modification of conditions for macroscopic quantum self-trapping.

Abstract

An atomic Josephson junction realized with dipolar bosons in a double-well potential can be described by an extended Bose-Hubbard model in which dipolar interactions generate an effective on-site interaction and nearest-neighbor pair tunneling. Using mean-field theory and exact diagonalization, we investigate how this correlated process affects zero-temperature equilibrium and dynamical properties of the system. In equilibrium, we show that pair tunneling induces ground-state parity modulations and significantly reshapes the phase diagram, producing qualitative changes in the quantum phase transitions toward NOON and phase-NOON states, as well as quantitative shifts of the critical points. Out of equilibrium, we demonstrate that it modifies the conditions for macroscopic quantum self-trapping, and assess its impact by comparing mean-field and fully quantum evolution, including the emergence of dynamical quantum phase transitions.