Entropy transport through a superfluid quantum point contact: A Keldysh field-theory approach

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Main Authors: Bertolusso, Davide, Bolech, C. J., Giamarchi, Thierry
Format: Preprint
Published: 2026
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author Bertolusso, Davide
Bolech, C. J.
Giamarchi, Thierry
author_facet Bertolusso, Davide
Bolech, C. J.
Giamarchi, Thierry
contents 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.
format Preprint
id arxiv_https___arxiv_org_abs_2605_00679
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Entropy transport through a superfluid quantum point contact: A Keldysh field-theory approach
Bertolusso, Davide
Bolech, C. J.
Giamarchi, Thierry
Quantum Gases
Mesoscale and Nanoscale Physics
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.
title Entropy transport through a superfluid quantum point contact: A Keldysh field-theory approach
topic Quantum Gases
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2605.00679