◇Quantum-Enhanced Measurement

Collective quantum correlations reduce spin noise along a useful measurement axis.

One optical quadrature can fluctuate less than the vacuum reference.

Collective phase accumulation can amplify a small signal.

Correlated signal and idler modes can improve target discrimination in noisy environments.

A phase-referenced local oscillator converts optical field quadratures into electrical signals.

Two coherent paths turn a tiny path-length difference into an intensity imbalance.