Microwave assisted transparency in an M-system

Abstract

In this work we theoretically study a five-level M-system whose two unpopulated ground states are coupled by a microwave (MW) field. The key feature which makes the M-system more efficient in comparison to a routinely studied closed loop Λ-system is the absence of MW field induced population transfer even at high intensities of the latter. The limitation of closed loop Λ systems due to MW induced population redistribution among the ground states, which reduces the atomic coherences, can be overcome in the M-system. We examine lineshape of probe absorption as a function of its detuning in the presence of both control and MW fields. The MW field facilitates the narrowing of the probe absorption lineshape in M-systems which is in contrast to closed loop Λ-systems. Hence this study opens up a new avenue for atom-based phase-dependent MW magnetometry.