Josephson effect at finite temperature along the BCS-BEC crossover

Abstract

The Josephson current-phase characteristics, that arise when a supercurrent flows across two fermionic superfluids separated by a potential barrier, can be controlled by varying either the inter-particle coupling or the temperature. While the coupling dependence has been addressed in detail both theoretically and experimentally for an attractive Fermi gas undergoing the BCS-BEC crossover, a corresponding study of the temperature dependence of the Josephson characteristics is still lacking in this context. Here, we investigate the combined coupling and temperature dependence of the Josephson characteristics in a systematic way for a wide set of barriers, within ranges of height and width that can be experimentally explored. Our study smoothly connects the two limiting cases, of non-overlapping composite bosons at low temperature described by the Gross-Piatevskii equation, and of strongly overlapping Cooper pairs near the critical temperature described by the Ginzburg-Landau equation. In this way, we are able to explore several interesting effects related to how the current-phase characteristics evolve along the BCS-BEC crossover as a function of temperature and of barrier shape. These effects include the coherence length outside the barrier and the pair penetration length inside the barrier (which is related to the proximity effect), as well as the temperature evolution of the Landau criterion in the limit of a vanishingly small barrier. A comparison is also presented between the available experimental data for the critical current and our theoretical results over a wide range of couplings along the BCS-BEC crossover.

arXiv comment25 pages, 26 figures

References in corpus (27)

• The BCS-BEC crossover: From ultra-cold Fermi gases to nuclear systems
• Phase controlled superconducting proximity effect probed by tunneling spectroscopy
• Critical velocity for superfluid flow across the BEC-BCS crossover
• BCS-BEC crossover at finite temperature in the broken-symmetry phase
• From the Bogoliubov-de Gennes equations for superfluid fermions to the Gross-Pitaevskii equation for condensed bosons
• The Ginzburg-Landau theory in application
• The critical velocity in the BEC-BCS crossover
• Condensate Fraction of a Fermi Gas in the BCS-BEC Crossover
• Strongly correlated superfluid order parameters from dc Josephson supercurrents
• An ideal Josephson junction in an ultracold two-dimensional Fermi gas
• The Josephson effect throughout the BCS-BEC crossover
• Solution of the Bogoliubov-de Gennes equations at zero temperature throughout the BCS-BEC crossover: Josephson and related effects
• Critical temperature and Ginzburg-Landau equation for a trapped Fermi gas
• Landau critical velocity in weakly interacting Bose gases
• Atypical BCS-BEC crossover induced by quantum-size effects
• Temperature dependence of the pair coherence and healing lengths for a fermionic superfluid throughout the BCS-BEC crossover
• Gap equation with pairing correlations beyond mean field and its equivalence to a Hugenholtz-Pines condition for fermion pairs
• Temperature dependence of a vortex in a superfluid Fermi gas
• Critical Josephson current in BCS-BEC crossover superfluids
• Equation for the superfluid gap obtained by coarse graining the Bogoliubov-de Gennes equations throughout the BCS-BEC crossover
• Critical Behaviour in Trapped Strongly Interacting Fermi Gases
• Josephson oscillations and self-trapping of superfluid fermions in a double-well potential
• Vortex arrays in neutral trapped Fermi gases throughout the BCS-BEC crossover
• From superconducting fluctuations to the bosonic limit in the response functions above the critical temperature
• Pair correlations in the normal phase of an attractive Fermi gas
• Optimizing the proximity effect along the BCS-BEC crossover
• Non-local equation for the superconducting gap parameter

Cited by in corpus (8)

• Dissipation Mechanisms in Fermionic Josephson Junction
• Persistent currents in ultracold gases
• Multi-Particle Tunneling Transport at Strongly-Correlated Interfaces
• Nonequilibrium noise as a probe of pair-tunneling transport in the BCS--BEC Crossover
• Dissipation in a Finite Temperature Atomic Josephson Junction
• Quantum fluctuations in atomic Josephson junctions: the role of dimensionality
• SNS Junctions along the BCS-BEC Crossover
• Inclusion of pairing fluctuations in a semiclassical approach: The case of study of the Josephson effect