Experimental Study Of Light Storage In ⁸⁷Rb Hot Atomic Ensemble By Using Electromagnetically Induced Transparency

Long distance quantum communication networks have attracted widespread attention with the development of quantum information.Quantum repeater is a necessary step for long distance quantum communication networks.Optical storage is the foundation of quantum repeater.So optical storage has become an important research topic.Atom is considered to be an ideal storage medium because of its long coherence time in ground states.The methods that light storage in atomic ensemble include electromagnetically induced transparency,Raman two-photon process and so on.Electromagnetically induced transparency is an effective means of storage.It can keep quantum states of optics when storing the non-classical field using electromagnetically induced transparency.So it attracts widespread research.The hot atomic ensemble has a relative simple experimental system and it is easy to manipulate.These made researchers have been studying how to storage non-classic light field in hot atomic ensemble.Our article research the storage of coherent light field in hot ⁸⁷Rb atoms.This work provide experimental basis for the storage of non-classic light field in hot atomic ensemble.In addition,we obtain 397.5 nm light emission by frequency doubling,which as pumping light of the spontaneous parametric down-conversion process.This provide basis for the next step to generate entangled light source.This paper research the storage and release of coherent light field in hot ⁸⁷Rb atoms using electromagnetically induced transparency effect.In order to obtain high storage retrieval efficiency and reduce extra noise that introduced in the process of storage,and then achieving high fidelity of continuous variable light field storage.We study the effects of the two-photon detuning on light pulse delay and light storage retrieval pulses at 650 MHz one-photon red detuning.The specific contents are as follows:Firstly,we simple introduce electromagnetically induced transparency and light storage based on electromagnetically induced transparency.Secondly,we achieve the storage and release of probe using electromagnetically induced transparency effect in hot ⁸⁷Rb atoms.We study the effects of two-photon detuning on light storage and light pulse delay at 650 MHz one-photon red detuning and analyze the experimental measurement in theory.The results show us the retrieval and delay signal are significant when two-photon detuning within 0.5 MHz.The shapes of slow light are consistent with theory,however,the retrieval signal shapes change with the increase of two-photon detuning.This is caused by interference between multiple EIT subsystems.Thirdly,we research the probe storage signal shapes and retrieval efficiency as a function of storage time both in the condition of two-photon resonance and two-photon detuning.The results show us the retrieval signal shapes unchanged with the increase of storage time at two-photon resonance.But the retrieval signal shapes appears periodically oscillation with the increase of storage time under the condition of two-photon detuning.This is caused by interference between multiple EIT subsystems.Fourthly,we obtain 397.5nm light emission by frequency doubling using circular frequency doubling cavity.When the pumping is 415mW,795nm,we obtain 67.5mW,397.5nm light,which as pumping light of the spontaneous parametric down-conversion process.This provide basis for the next step to generate entangled light source.