Spin-orbit-coupled fermions in an optical lattice clock.

Area of Science:

• Atomic, Molecular, and Optical Physics
• Condensed Matter Physics
• Quantum Simulation

Background:

• Engineered spin-orbit coupling (SOC) in cold atoms is crucial for studying synthetic materials and condensed matter phenomena.
• Spontaneous emission in alkali-atom SOC systems causes heating, limiting many-body effect observations.
• Research is ongoing for alternative methods to overcome these limitations.

Purpose of the Study:

• To demonstrate naturally occurring spin-orbit-coupled fermions in a one-dimensional optical lattice clock.
• To utilize ultra-narrow optical clock transitions for SOC generation and probing.
• To leverage the long excited state lifetime for precise measurements and eliminate decoherence.

Main Methods:

• Utilized a 1D optical lattice clock with 87Sr atoms.
• Employed clock spectroscopy for preparing lattice band populations, electronic states, and quasi-momenta.
• Generated and probed spin-orbit-coupled dynamics using ultra-narrow optical clock transitions.
• Used momentum- and spin-resolved in situ probing of SOC band structure.

Main Results:

• Successfully engineered naturally occurring spin-orbit coupling in fermionic strontium atoms.
• The long excited clock state lifetime (160 s) prevented decoherence and atom loss.
• Observed Bloch oscillations, spin-momentum locking, and Van Hove singularities.
• Probed the SOC band structure and eigenstates with high precision.

Conclusions:

• Demonstrated a novel method for creating and studying spin-orbit coupling in fermionic atoms using optical lattice clocks.
• Overcame limitations of spontaneous emission and heating inherent in previous SOC experiments.
• Laid the foundation for using fermionic optical lattice clocks to explore new quantum phases of matter.