Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

arXiv:1712.07125 · Physical Review A

Controlled transport between Fermi superfluids through a quantum point contact

Juan Yao, Boyang Liu, Mingyuan Sun, Hui Zhai

Published Oct 8, 2018• 16 citations
arXivHTMLPDF

Abstract

Recent advances in experimental techniques allow one to create a quantum point contact between two Fermi superfluids in cold atomic gases with a tunable transmission coefficient. In this Rapid Communication we propose that three distinct behaviors of charge transports between two Fermi superfluids can be realized in this single setup, which are the multiple Andreev reflection, the self-trapping, and the Josephson oscillation. We investigate the dynamics of atom number difference between two reservoirs for different initial conditions and different transmission coefficients, and present a coherent picture of how the crossover between different regimes takes place. Our results can now be directly verified in the current experimental system.

DOI
10.1103/physreva.98.041601

Related papers

Connecting strongly correlated superfluids by a quantum point contact

Dominik Husmann, Shun Uchino, Sebastian Krinner +4 more

Point contacts provide simple connections between macroscopic particle reservoirs. In electric circuits, strong links between metals, semiconductors, or superconductors have applications for fundamental condensed-matter physics as well as quantum information processing. However, for complex, strongly correlated materials, links have been largely restricted to weak tunnel junctions. We studied resonantly interacting Fermi gases connected by a tunable, ballistic quantum point contact, finding a nonlinear current-bias relation. At low temperature, our observations agree quantitatively with a theoretical model in which the current originates from multiple Andreev reflections. In a wide contact geometry, the competition between superfluidity and thermally activated transport leads to a conductance minimum. Our system offers a controllable platform for the study of mesoscopic devices based on strongly interacting matter.

arXiv:1508.00578•Science•Dec 17, 2015•134 citations

Connecting strongly correlated superfluids by a quantum point contact

Dominik Husmann, Shun Uchino, Sebastian Krinner +4 more

Point contacts provide simple connections between macroscopic particle reservoirs. In electric circuits, strong links between metals, semiconductors, or superconductors have applications for fundamental condensed-matter physics as well as quantum information processing. However, for complex, strongly correlated materials, links have been largely restricted to weak tunnel junctions. We studied resonantly interacting Fermi gases connected by a tunable, ballistic quantum point contact, finding a nonlinear current-bias relation. At low temperature, our observations agree quantitatively with a theoretical model in which the current originates from multiple Andreev reflections. In a wide contact geometry, the competition between superfluidity and thermally activated transport leads to a conductance minimum. Our system offers a controllable platform for the study of mesoscopic devices based on strongly interacting matter.

•Jan 1, 2015•56 citations

Tunneling and Self-Trapping of Superfluid Fermi Gases in BCS-BEC Crossover

Yu Long Zhou, Ying Wang, Wenchen Luo +1 more

We investigate tunneling and self-trapping of superfluid Fermi gases under a two-mode ansatz in different regimes of the crossover from Bardeen—Cooper—Schrieffer (BCS) superfluid to Bose—Einstein condensates (BEC). Starting from a generalized equation of state, we derive the coupled equations of relative atom-pair number and relative phase about superfluid Fermi gases in a double-well system and then classify the different oscillation behaviors by the tunneling strength and interactions between atoms. Tunneling and self-trapping behaviors are considered in the whole BCS-BEC crossover in the case of a symmetric double-well potential. We show that the nonlinear interaction between atoms makes the self-trapping more easily realized in BCS regime than in the BEC regime and stability analysis is also given.

Communications in Theoretical Physics•Feb 1, 2012•5 citations

Self-trapping and Macroscopic Tunnelling of Superfluid Fermi Gases in Multi-well Potentials

Hong-Ping Xu, Ju-Kui Xue

We study the tunnelling dynamics of superfluid Fermi gases trapped in multi-well system along the BEC-BCS crossover. Within the hydrodynamical model and by using the multi-mode approximation, the self-trapping dynamics of superfluid Fermi gases in multi-well system are obtained numerically. We find that the self-trapping to diffusion transition strongly depends on the well number. When the well number is less than three, the self-trapped state takes place easier on the BEC side than that on the BCS side. However, when the well number is larger than three, the self-trapped state takes place easier on the BCS side instead of the BEC side. Furthermore, by considering a superfluid of 40 K atoms, we obtain the zero-mode and π-mode Josephson frequencies of coherent atomic oscillations in double-well system. It is noteworthy that the Josephson mode, especially, the existence of π-mode frequency strongly depends on the atoms number on the BCS side.

Communications in Theoretical Physics•Jul 1, 2012•0 citations

INTRODUCTION TO THE TRANSPORT OF FERMI GASES THROUGH QUANTUM POINT CONTACTS

Chunyuan SHAN, Xiaoyu Dai, Boyang Liu

Transport measurement is an important tool for studying the fundamental properties of matter. Among them, transport through quantum point contacts is a very interesting phenomenon in mesoscopic physics. In non-interacting or weakly interacting Fermi systems, the conductivity exhibits quantized behavior as a function of gate voltage, revealing the quantum nature of matter. In recent years, transport in cold atomic systems has become one of the frontiers in this field. Cold atomic systems have highly are controllable and exhibit many novel phases, leading to new experimental phenomena that cannot be observed in traditional material physics. This article will review some of the latest experimental progress in transport through quantum point contacts in cold atomic Fermi gases, and will also introduce the non-equilibrium field theoretical methods commonly used to study this system.

Wuli yu gongcheng.•Oct 1, 2023•0 citations

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

Davide Bertolusso, C. J. Bolech, Thierry Giamarchi

We study the matter and entropy transport between two ultracold 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.

arXiv:2605.00679•Physical Review Research•Aug 17, 2026•0 citations
Recent advances in experimental techniques allow one to create a quantum point contact between two Fermi superfluids in cold atomic gases with a tunable transmission coefficient. In this Rapid Communication we propose that three distinct behaviors of charge transports between two Fermi superfluids can be realized in this single setup, which are the multiple Andreev reflection, the self-trapping, and the Josephson oscillation. We investigate the dynamics of atom number difference between two reservoirs for different initial conditions and different transmission coefficients, and present a coherent picture of how the crossover between different regimes takes place. Our results can now be directly verified in the current experimental system.
Point contacts provide simple connections between macroscopic particle reservoirs. In electric circuits, strong links between metals, semiconductors, or superconductors have applications for fundamental condensed-matter physics as well as quantum information processing. However, for complex, strongly correlated materials, links have been largely restricted to weak tunnel junctions. We studied resonantly interacting Fermi gases connected by a tunable, ballistic quantum point contact, finding a nonlinear current-bias relation. At low temperature, our observations agree quantitatively with a theoretical model in which the current originates from multiple Andreev reflections. In a wide contact geometry, the competition between superfluidity and thermally activated transport leads to a conductance minimum. Our system offers a controllable platform for the study of mesoscopic devices based on strongly interacting matter.
Point contacts provide simple connections between macroscopic particle reservoirs. In electric circuits, strong links between metals, semiconductors, or superconductors have applications for fundamental condensed-matter physics as well as quantum information processing. However, for complex, strongly correlated materials, links have been largely restricted to weak tunnel junctions. We studied resonantly interacting Fermi gases connected by a tunable, ballistic quantum point contact, finding a nonlinear current-bias relation. At low temperature, our observations agree quantitatively with a theoretical model in which the current originates from multiple Andreev reflections. In a wide contact geometry, the competition between superfluidity and thermally activated transport leads to a conductance minimum. Our system offers a controllable platform for the study of mesoscopic devices based on strongly interacting matter.
We investigate tunneling and self-trapping of superfluid Fermi gases under a two-mode ansatz in different regimes of the crossover from Bardeen—Cooper—Schrieffer (BCS) superfluid to Bose—Einstein condensates (BEC). Starting from a generalized equation of state, we derive the coupled equations of relative atom-pair number and relative phase about superfluid Fermi gases in a double-well system and then classify the different oscillation behaviors by the tunneling strength and interactions between atoms. Tunneling and self-trapping behaviors are considered in the whole BCS-BEC crossover in the case of a symmetric double-well potential. We show that the nonlinear interaction between atoms makes the self-trapping more easily realized in BCS regime than in the BEC regime and stability analysis is also given.
We study the tunnelling dynamics of superfluid Fermi gases trapped in multi-well system along the BEC-BCS crossover. Within the hydrodynamical model and by using the multi-mode approximation, the self-trapping dynamics of superfluid Fermi gases in multi-well system are obtained numerically. We find that the self-trapping to diffusion transition strongly depends on the well number. When the well number is less than three, the self-trapped state takes place easier on the BEC side than that on the BCS side. However, when the well number is larger than three, the self-trapped state takes place easier on the BCS side instead of the BEC side. Furthermore, by considering a superfluid of 40 K atoms, we obtain the zero-mode and π-mode Josephson frequencies of coherent atomic oscillations in double-well system. It is noteworthy that the Josephson mode, especially, the existence of π-mode frequency strongly depends on the atoms number on the BCS side.
Transport measurement is an important tool for studying the fundamental properties of matter. Among them, transport through quantum point contacts is a very interesting phenomenon in mesoscopic physics. In non-interacting or weakly interacting Fermi systems, the conductivity exhibits quantized behavior as a function of gate voltage, revealing the quantum nature of matter. In recent years, transport in cold atomic systems has become one of the frontiers in this field. Cold atomic systems have highly are controllable and exhibit many novel phases, leading to new experimental phenomena that cannot be observed in traditional material physics. This article will review some of the latest experimental progress in transport through quantum point contacts in cold atomic Fermi gases, and will also introduce the non-equilibrium field theoretical methods commonly used to study this system.
We study the matter and entropy transport between two ultracold 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.