Dissipation in a finite-temperature atomic Josephson junction

Year: 2022

Authors: Xhani K., Proukakis NP.

Autors Affiliation: Newcastle Univ, Joint Quantum Ctr JQC Durham Newcastle, Sch Math Stat & Phys, Newcastle Upon Tyne NE1 7RU, England; CNR INO, European Lab Nonlinear Spect LENS, I-50019 Sesto Fiorentino, Italy.

Abstract: We numerically demonstrate and characterize the emergence of distinct dynamical regimes of a finitetemperature bosonic superfluid in an elongated Josephson junction generated by a thin Gaussian barrier over the entire temperature range where a well-formed condensate can be clearly identified. Although the dissipation arising from the coupling of the superfluid to the dynamical thermal cloud increases with increasing temperature as expected, the importance of this mechanism is found to depend on two physical parameters associated (i) with the initial chemical potential difference, compared to some characteristic value, and (ii) the ratio of the thermal energy to the barrier amplitude. The former determines whether the superfluid Josephson dynamics are dominated by gradually damped plasmalike oscillations (for relatively small initial population imbalances), or whether dissipation at early times is instead dominated by vortex- and sound-induced dissipation (for larger initial imbalances). The latter defines the effect of the thermal cloud on the condensate dynamics, with a reversal of roles, i.e., the condensate being driven by the oscillating thermal cloud, being observed when the thermal particles acquire enough energy to overcome the barrier. Our findings are within current experimental reach in ultracold superfluid junctions.

Journal/Review: PHYSICAL REVIEW RESEARCH

Volume: 4 (3)      Pages from: 33205-1  to: 33205-20

More Information: We acknowledge discussions with Kean Loon Lee, I-Kang (Gary) Liu, Giacomo Roati, Francesco Scazza, and Matteo Zaccanti, and financial support from the QuantERA Project NAQUAS (EPSRC EP/R043434/1) , and Qombs Project (FET Flagship on Quantum Technologies Grant No. 820419) .
KeyWords: Double-well; Coherent Oscillations; Quantum Dynamics; Condensate
DOI: 10.1103/PhysRevResearch.4.033205

Citations: 4
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