Mapping of spin-orbit coupling mode of vector vortex light using electromagnetically induced transparency

We report a novel pump-probe laser spectroscopy technique to measure the spatial polarization of spin-orbit coupling (SOC) mode of the vector vortex beam (VVB) using electromagnetically induced transparency (EIT) protocol. An experiment is performed for observing the EIT signal in a five-level Λ-type configuration of 85Rb-D2 line coupled with the pump VVB and non-vortex probe beam. Interestingly, the sinusoidal modulation of the EIT amplitude is observed with spatial polarization rotation of the pump VVB for two different orbital angular momenta (OAM). This remarkable feature enables the extraction of information about the spatial polarization and azimuthal petal-like pattern of the SOC mode of the VVB. Furthermore, we propose that the experimental results may be considered as a hybrid quantum logic gate operation by employing the spatial polarization and EIT amplitude as the photonic qubits, which may offer promising applications in quantum information science.