Toward Unitary Spin Squeezing for Atomic Clocks

Improving the precision of sensors using entanglement is a major goal in quantum metrology. Techniques for producing spin squeezing in atomic systems are often non-unitary, generating more anti-squeezing than the minimum prescribed by the uncertainty principle. We find that non-unitary squeezing significantly impedes the potential improvements from squeezing in atomic clocks and other quantum sensors. I will present the method and realization of near-unitary spin squeezing with $\mathrm{^{171}Yb}$ atoms by off-resonant probing in a high-finesse optical resonator. This technique will allow for the creation of quantum states with metrologically useful entanglement on the clock transition of $\mathrm{^{171}Yb}$.