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Nonequilibrium Transport in a Superfluid Josephson Junction Chain: Is There Negative Differential Conductivity?
Samuel E Begg1,2, Matthew J Davis2, Matthew T Reeves2
1Asia Pacific Center for Theoretical Physics, Pohang 37673, Korea.
Physical Review Letters
|March 22, 2024
Summary
Quantum transport in Josephson junction chains shows negative differential conductivity (NDC) is only valid in the weak coupling regime. Quantum fluctuations significantly impact filling dynamics, suggesting a hybrid behavior with the ac Josephson effect.
Area of Science:
- Quantum physics
- Condensed matter physics
- Atomic physics
Background:
- Far-from-equilibrium quantum transport dynamics in 1D Josephson junction chains.
- Experimental observation of negative differential conductivity (NDC) in multimode Bose-Einstein condensates.
Purpose of the Study:
- Develop a theoretical model to examine experimental results on NDC in Josephson junction chains.
- Investigate the role of quantum fluctuations and spatial phase variations on filling dynamics.
- Clarify the validity of NDC interpretation and explore hybrid behaviors.
Main Methods:
- Unitary c-field description for quantum transport dynamics.
- Quantitative reproduction of experimental data across various tunnel couplings.
- Analysis of spatial phase variations due to quantum fluctuations.
Main Results:
- The unitary c-field model accurately reproduces experimental results without fitted parameters.
- Filling dynamics are highly sensitive to spatial phase variations from quantum fluctuations.
- NDC interpretation is invalid outside the weak coupling regime.
Conclusions:
- The device exhibits a hybrid behavior of NDC and ac Josephson effect in the weak coupling regime.
- Atomtronic implementations require models incorporating quantum fluctuations.
- The interpretation of NDC in this system is limited and context-dependent.
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