Orientation-Dependent Entanglement Lifetime in a Squeezed Atomic Clock

Understand

We study experimentally the lifetime of a special class of entangled states in an atomic clock, squeezed spin states.

• In the presence of anisotropic noise, their lifetime is strongly dependent on squeezing orientation.
• We measure the Allan deviation spectrum of a clock operated with a phase-squeezed input state.
• For integration times up to 50 s the squeezed clock achieves a given precision 2.8(3) times faster than a clock operating at the standard quantum limit.