Entropy transport through a superfluid quantum point contact: A Keldysh field-theory approach
Davide Bertolusso, C. J. Bolech, Thierry Giamarchi
TLDR
This paper uses Keldysh field theory to study matter and entropy transport in superfluid quantum point contacts, finding oscillatory entropy current.
Key contributions
- Investigates matter and entropy transport in superfluid quantum point contacts using Keldysh formalism.
- Derives current-bias characteristics for both particle and entropy currents in the BCS regime.
- Discovers oscillatory behavior for the entropy current at low voltage in ballistic junctions.
- Compares theoretical predictions with experimental data from cold atomic gases.
Why it matters
This work extends the understanding of transport phenomena in superfluids beyond particle current to include entropy. The discovery of oscillatory entropy current provides new insights into non-equilibrium dynamics. It offers a theoretical framework validated against experiments, which is crucial for future cold atom research.
Original Abstract
We study the matter and entropy transport between two ultra-cold neutral Fermi-gas reservoirs linked by a quantum point contact under a chemical-potential gradient. We describe the two leads with a BCS mean-field model and derive the current-bias characteristics for both particle and entropy transport. We compute the out of equilibrium steady-state currents by using the Keldysh formalism. In accordance with previous works in the literature, we confirm the well-known behavior for the particle current and extend the computation to the entropy current in the BCS regime. The entropy current shows an oscillatory behavior at low voltage in the ballistic junction limit. We analyze the results for a wide range of values of the junction's transparency. We also compare our findings with experimental results in cold atomic gases in the unitary regime.
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