Coherent Raman spectroscopy of the quantum-entangled exciton-Mn2+ state in CdTe

Electron paramagnetic resonance of Mn2+ ions in CdTe was detected using coherent Raman electron spin resonance spectroscopy (CRESR) with microwave frequencies of 13.8 and 33.7 GHz. It was possible to resolve the effects of both the hyperfine interaction between the Mn2+ 3d5 electrons and the manganese nucleus and the cubic crystal field. From the optical resonance profile, it is shown that the coherent Raman signal is resonant with an excitonic state and is due to the exchange interactions between the Mn2+ 3d5 electrons and the hole of the exciton. The existence of a CRESR signal under these circumstances provides a direct demonstration that coherence is maintained between the exciton and Mn2+ systems via this exchange interaction.