Dynamical Manipulation Of Optical Nonreciprocity In Homogeneous Atomic Medium

Non-reciprocal quantum optics has been the core concept for realizing novel photonic devices such as all-optical diodes and chip isolators,which are characterized by high efficiency,stability and undemanding to integration,particularly critical in quantum computing and information processing.In this paper,we use the coherent regulation of laser fields to realize the non-reciprocity of probe light reflection based on isotropic medium with uniform distribution of atomic density.The details are as follows: Firstly,in the first work,a four-level tripod coherent atom model system is constructed by using two strongly coupled fields and a weak probe field to interact with atoms.In this system,the real and imaginary parts of the susceptibility keep to Parity-Time(PT)antisymmetry and symmetry by controlling the linear variation of the coupling field intensity in the spatial domain,thus realizing the dynamic regulation of the two-color non-reciprocal light reflection.Particluarly,two-color unidirectional reflection can even be achieved at the EIT window.Then,in the second work,we adjust the Rabi frequency of the coupling field as a function that varies by spatial periodicity.In the simple three-level Λ coherent atom model,the real and imaginary parts of the modulating susceptibility still satisfy the PT symmetric and antisymmetric relations,and indicates a necessary and sufficient conditions for realizing reflective non-reciprocity.The rule of reflective non-reciprocity changing periodically with the coupling field is obtained and we can control the probe light transmission spectrum to appear or disappear.Finally,in the third work,the gain of probe light is realized by adding microwave field in V model coherent atom system,and then the amplification of non-reciprocal light reflection is realized with the spatial modulation susceptibility of strong coupling field varying with position.Further,the frequency range and contrast of the non-reciprocal reflection are modulated by the relative phase between the three laser fields.In conclusion,our work provides more possibilities for the manipulation of non-reciprocal light propagation and has potential applications in quantum computing and information transmission.