Scientific Results

Dynamical phase diagram of ultracold Josephson junctions

Year: 2020

Authors: Xhani K., Galantucci L., Barenghi CF., Roati G., Trombettoni A., Proukakis NP.

Autors Affiliation: Newcastle Univ, Sch Math Stat & Phys, Joint Quantum Ctr JQC Durham Newcastle, Newcastle Upon Tyne NE1 7RU, Tyne & Wear, England;‎ Univ Firenze, European Lab Nonlinear Spect LENS, I-50019 Sesto Fiorentino, Italy; CNR, Ist Nazl Ott, INO, I-50019 Sesto Fiorentino, Italy; Univ Trieste, Dept Phys, Str Costiera 11, I-34151 Trieste, Italy; CNR, IOM DEMOCRITOS Simulat Ctr, Via Bonomea 265, I-34136 Trieste, Italy; SISSA, Via Bonomea 265, I-34136 Trieste, Italy

Abstract: We provide a complete study of the phase diagram characterising the distinct dynamical regimes emerging in a three-dimensional Josephson junction in an ultracold quantum gas. Considering trapped ultracold superfluids separated into two reservoirs by a barrier of variable height and width, we analyse the population imbalance dynamics following a variable initial population mismatch. We demonstrate that as the chemical potential difference is increased, the system transitions from Josephson plasma oscillations to either a dissipative (in the limit of low and narrow barriers) or a self-trapped regime (for large and wider barriers), with a crossover between the dissipative and the self-trapping regimes which we explore and characterize for the first time. This work, which extends beyond the validity of the standard two-mode model, connects the role of the barrier width, vortex rings and associated acoustic emission with different regimes of the superfluid dynamics across the junction, establishing a framework for its experimental observation, which is found to be within current experimental reach.


Volume: 22 (12)      Pages from: 123006-1  to: 123006-23

KeyWords: Josephson junction; superfluid quantum transport; dissipation; self-trapping; vortex rings; sound waves
DOI: 10.1088/1367-2630/abc8e4

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