Near-Unitary Spin Squeezing in ^{171}Yb.

Area of Science:

• Atomic physics
• Quantum metrology
• Optical atomic clocks

Background:

• Spin squeezing surpasses the standard quantum limit (SQL) for atomic precision measurements.
• Unitary spin squeezing is crucial for advancing atomic clock performance.

Purpose of the Study:

• To achieve substantial and nearly unitary spin squeezing in ^{171}Yb atoms.
• To demonstrate the application of spin-squeezed states in improving atomic interferometry.

Main Methods:

• Utilized cavity feedback with light detuned from resonance to generate spin-squeezed states in ^{171}Yb.
• Employed an interferometer to measure the precision enhancement achieved with squeezed states.

Main Results:

• Achieved substantial and nearly unitary spin squeezing in a collective nuclear spin of ~10^3 ^{171}Yb atoms.
• Observed a precision gain of 6.5(4) dB over the SQL, limited by readout.
• Demonstrated a factor of 3.7(2) improvement in averaging time using a squeezed state.

Conclusions:

• Cavity-feedback-generated spin squeezing in ^{171}Yb offers a promising route to enhanced atomic precision.
• The demonstrated technique can be transferred to the optical-clock transition for future clock improvements.