Observation of Spin Squeezing with Contact Interactions in One- and Three-Dimensional Easy-Plane Magnets

Area of Science:

• Atomic physics
• Quantum optics
• Condensed matter physics

Background:

• Spin squeezing is a quantum phenomenon indicating entanglement.
• It enables measurement sensitivities surpassing classical limits.
• Ultracold atoms in optical lattices are a key platform for studying many-body quantum systems.

Purpose of the Study:

• To demonstrate and investigate spin squeezing in ultracold ^{7}Li atoms using short-range interactions in 1D and 3D.
• To understand the impact of density fluctuations (holes) on spin squeezing dynamics.
• To develop a theoretical model for spin-density coupling in these systems.

Main Methods:

• Experimental realization of spin squeezing in 1D and 3D optical lattices with ultracold ^{7}Li atoms.
• Utilizing short-range contact interactions for spin squeezing.
• Developing a theoretical model incorporating spin-density coupling.

Main Results:

• Spin squeezing was successfully demonstrated in both 1D and 3D.
• In 1D, spin squeezing was robust against density fluctuations (holes).
• In 3D, holes significantly altered squeezing dynamics, hindering scalable squeezing, but a new model achieved quantitative agreement with experimental data (≈2 dB at 7% hole fraction).

Conclusions:

• Spin-density coupling is crucial for understanding the dynamics of interacting spins.
• The developed theoretical model accurately describes observed squeezing dynamics.
• Findings pave the way for enhancing spin squeezing in systems with short-range interactions.