Multiple Frequency Conversion Via Atomic Spin Coherence Of Storing Light Pulse

In further quantum information processing and quantum network, it is necessary to have some independent devices such as quantum memory, quantum repeater, and quantum routing, where quantum information can be exchanged between light fields and experimental mediums in a controlled fashion. Photons are efficient and robust information carriers due to their weak interaction with the environment, but it is difficult to manipulate them. Recent researches show that electromagnetically induced transparency (EIT) is a promising technique to manipulate the light fields. In particular, light storage based on EIT has attracted significant interest due to the applications in both classical and quantum information processing. An EIT‐driven medium is also used to enhance nonlinear optical interaction, which is very useful for frequency conversion. Recently, there have been some interests in using atomic nonlinearities to enhance light storage, or using light storage to enhance optical nonlinearities. Currently, most experiments on EIT effect have been carried out in atomic gases. For practical applications, a solid medium is preferred. The solid‐state mediums provide spatially fixed interaction centers, and do not suffer from atomic diffusion. So they can be considered as an alternative to atomic gases.Here we experimentally demonstrate multiple frequency conversion via atomic spin coherence of storing light pulse in a doped solid. The essence of this multiple frequency conversion is four‐wave mixing based on stored atomic spin coherence. Through electromagnetically induced transparency, an input probe pulse is stored into atomic spin coherence by modulating the intensity of the control field. By using two different control fields to interact with the coherently prepared medium, the stored atomic spin coherence can be transformed into three different information channels. Multiple frequency conversion is implemented efficiently by manipulating the spectrum of the control fields scattering atomic spin coherence. We further study that three generated signals corresponding to three different physical processes. This multiple frequency conversion allows for coherently manipulating the light field in a controlled fashion, and is expected to have potential applications in information processing and communication network.