Experimental Investigation For Frequency Non-degenerate Light Memory In Hot Atomic Ensembles

In recent years, quantum information is an important research area. With the development of quantum information science, quantum information network has attracted more and more attention. The quantum repeater is the key of quantum information network development and quantum memory is the foundation of quantum repeaters[1], so the quantum information storage has been a hot topic at present [2]. Photons are the fastest and very robust carriers of quantum states. Atomic ensemble is a good candidate of quantum memory unit [3]. The interaction between light and atoms provides an effective way to transfer between the quantum information and light to the spin wave [4]. The protocol which use of the electromagnetically induced transparency (EIT) effect and Raman process to store the quantum information of light has become an important task in quantum information science.This paper demonstrates the experimental study of light storage, based on the non degenerate A-type three level structures in the hot atomic ensemble. Compared to the cold atomic ensembles, the hot atom system is relatively simple for practical application. Atomic coherence time can be extended by filling the buffer gas. In the non-degenerate△-type three-level atomic system, the frequency of two ground states is large, we can separate the weak retrieval signal light and the strong readout light effectively. So the non-degenerate A-type three-level atomic system is widely used in quantum memory. We realize the quantum memory via EIT and Raman Effect in the non-degenerate△-type three-level atomic system. The specific contents are as follows:1) we demonstrate the EIT effect[5] and Raman process in A type three level atomic system, and optical memory.2) We realized the frequency locking of the MBR-110by using the saturated absorption spectroscopy technology. Then, we used the difference frequency locking technique to lock the frequency difference between Ti:sapphire lasers and the semiconductor lasers to6.8GHz. And we experimentally study the optical memory in EIT non-degenerate△-type three-level atomic system.3) By double pass1.7GHz AOM, we get two coherent light beams, which meet the two-photon resonance in non-degenerate△-type three-level atomic system. We experimentally realize the off-resonance Raman memory in non degenerate△-type three-level85Rb hot atomic system. We study the relationship between storage efficiency (storage time) and single photon detuning.