A compact microchip atomic clock based on all-optical interrogation of ultra-cold trapped Rb atoms

摘要

We propose a compact atomic clock that uses all-optical interrogation of ultra-cold Rb atoms that are magnet-ically trapped near the surface of an atom microchip. The in-terrogation scheme, which combines electromagnetically in-duced transparency with Ramsey's method of separated os-cillatory fields, can achieve an atomic shot-noise-level per-formance better than l0~(-13)/ τ~(1/2) for 10~6 atoms. A two-color Mach-Zehnder interferometer can detect a 100-pW probe beam at the optical shot-noise level using conventional pho-todetectors. This measurement scheme is nondestructive and therefore can be used to increase the operational duty cy-cle by reusing the trapped atoms for multiple clock cycles. Numerical calculations of the density matrix equations are used to identify realistic operating parameters at which AC Stark shifts are eliminated. By considering fluctuations in these parameters, we estimate that AC Stark shifts can be canceled to a level better than 2 × 10~(14). An overview of the apparatus is presented with estimates of cycle time and power consumption