Selective Control of High-Order Atomic Coherences

Abstract

Resonant enhancement of optical Kerr and higher order nonlinearities in multilevel systems under the conditions of electromagnetically-induced transparency might be useful for quantum signal processing. The main problem with these schemes is related to the selective measurement of high-order atomic coherences that requires multiphoton interactions for the production and detection. In this paper we present a method in which a single laser beam is used for the creation of required nonlinear interactions. It is based on the nonlinear magneto-optical rotation with frequency-modulated light. Using this technique, we measure the nonlinear Faraday rotation caused by four-photon atomic coherence in M-type system. The method is also applicable to the selective control of higher order atomic coherences.