Josephson effect in fermionic superfluids across the BEC-BCS crossover.

Area of Science:

• Quantum physics
• Condensed matter physics
• Superfluidity

Background:

• The Josephson effect is a macroscopic quantum phenomenon crucial for understanding superfluid states and their broken symmetry.
• Fermionic superfluids exhibit complex behaviors, particularly in the crossover between different superfluid regimes.

Purpose of the Study:

• To observe and analyze the Josephson effect between two coupled fermionic superfluids.
• To investigate the relationship between relative population and phase in fermionic superfluids across the BEC-BCS crossover.
• To explore the dissipative dynamics and vortex propagation in these systems.

Main Methods:

• Coupling two fermionic superfluids via a thin tunneling barrier.
• Inducing initial excitations from equilibrium to observe dynamic responses.
• Analyzing the system's behavior throughout the molecular Bose-Einstein condensate (BEC) to Bardeen-Cooper-Schrieffer (BCS) superfluid regime crossover.

Main Results:

• Successfully observed the Josephson effect between two fermionic superfluids.
• Demonstrated that relative population and phase are canonically conjugate variables.
• Observed dissipative dynamics attributed to vortex propagation for larger excitations.

Conclusions:

• The study confirms the Josephson effect in fermionic superfluids, highlighting the robustness of resonant superfluids.
• The findings provide a deeper understanding of quantum phenomena in superfluid systems.
• Results offer insights into the fundamental properties of superfluids across different regimes.