Composite picosecond control of atomic state through a nanofiber interface

Abstract

Accurate control of single emitters at nanophotonic interfaces may greatly expand the accessible quantum states of coupled optical spins in the confined geometry and to unveil exotic nonlinear quantum optical effects. However, the optical control is challenged by spatially varying light-atom coupling strength generic to nanophotonics. We demonstrate numerically that despite the nearfield inhomogenuity, nearly perfect atomic state control can be achieved by exploiting geometric robustness of optical transitions with composite picosecond excitations. Our proposal is followed by a proof-of-principle demonstration where an N = 3 composite sequence is applied to robustly invert the D1 population of free-flying 85 Rb atoms trespassing a nanofiber interface. The precise control is confirmed by comparing the D2 fiber transmission with full-level simulation of the mesoscopic light-atom interaction across the composite parameter space. We project the scheme to large N for precise phase patterning and arbitrary optical dipole control at the nanophotonic interface.