Interference Fringes at Detector
An atom beam is split by a π/2 pulse, the two paths enclose an area A, then recombined. Any phase difference — from rotation, gravity, or other inertial effects — shifts the fringes.
Atom interferometers measure g to 1 part in 10⁹, detect rotation at 6×10⁻¹⁰ rad/s — surpassing ring laser gyroscopes. Used to test the equivalence principle and measure G.