Planar quantum squeezing and atom interferometry

Understand

We obtain a lower bound on the sum of two orthogonal spin component variances in a plane.

• This gives a novel planar uncertainty relation which holds even when the Heisenberg relation is not useful.
• We investigate the asymptotic, large $J$ limit, and derive the properties of the planar quantum squeezed states that saturate this uncertainty relation.
• These states extend the concept of spin squeezing to any two conjugate spin directions.