Noise property of a four-level system in vee + ladder configuration

Abstract

We present the results of a theoretical study of the output amplitude noises of a four-level atomic system in vee + ladder configuration. The difference and connection of electromagnetically induced transparency and Autler–Townes splitting effects are investigated theoretically. The output amplitude noise of the probe field of two effects were compared, the quantum properties of the input field of the thin medium and the thick medium under Autler–Townes splitting or electromagnetically induced transparency (EIT) condition are maintained, the higher fidelity is obtained in the storage of the thick medium under the condition of EIT in non-classical states. The noise characteristics of the squeezed vacuum field after four-level coherent medium are studied; the noise of the output field is lowest when the detection light is far away from detuning. The double split of EIT window was made by the dynamic Stark splitting on the ground state of control field, the quantum properties of the input field in the strong-control field and strong-coupling field were maintained. The output noise spectrum is divided with the increase in the field strength, the maximum output squeezing is far away from the resonance.