Persistent Currents in Rings of Ultracold Fermionic Atoms

Area of Science:

• Atomic Physics
• Quantum Gases
• Condensed Matter Physics

Background:

• Ultracold atoms offer a controllable platform for studying quantum phenomena.
• Superfluidity in fermionic systems is crucial for understanding phenomena like superconductivity.
• Previous research utilized weakly interacting bosonic atoms for matter-wave circuits.

Purpose of the Study:

• To create and characterize persistent currents of ultracold fermionic atoms in a ring.
• To investigate the stability and behavior of these currents in the strongly interacting and BCS regimes.
• To explore the possibility of using fermionic atoms for building matter-wave circuits.

Main Methods:

• Trapping ultracold fermionic atoms in a ring configuration.
• Tuning atomic interactions to transition between superfluid and normal phases.
• Measuring lifetimes and stability of persistent currents.
• Analyzing the probability of quantized superflow reappearance.

Main Results:

• Persistent currents with lifetimes >10 seconds were achieved in the strongly interacting regime.
• Currents remained stable into the Bardeen-Cooper-Schrieffer (BCS) regime at low temperatures.
• The probability of quantized superflow reappearing after driving into the normal phase was insensitive to time and minimum interaction strength.
• Weak damping of normal currents was identified as the mechanism for superflow reappearance.

Conclusions:

• Ultracold fermionic atoms with tunable interactions can sustain persistent currents and exhibit quantized superflow.
• These systems are suitable for creating matter-wave circuits, analogous to those made with bosonic atoms.
• The robustness of superflow reappearance offers insights into quantum dissipation and memory effects.