Three-dimensional theory of quantum memories based onΛ-type atomic ensembles
| Autor: | Anders S. Sørensen, Emil Zeuthen, Anna Grodecka-Grad |
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| Rok vydání: | 2011 |
| Předmět: |
Physics
Quantum Physics Paraxial approximation FOS: Physical sciences Physics::Optics Type (model theory) 16. Peace & justice Lambda 01 natural sciences Atomic and Molecular Physics and Optics 010309 optics Spin wave Quantum mechanics 0103 physical sciences Optical depth (astrophysics) Fresnel number Quantum Physics (quant-ph) 010306 general physics Quantum information science Quantum |
| Zdroj: | Physical Review A. 84 |
| ISSN: | 1094-1622 1050-2947 |
| Popis: | We develop a three-dimensional theory for quantum memories based on light storage in ensembles of Lambda-type atoms, where two long-lived atomic ground states are employed. We consider light storage in an ensemble of finite spatial extent and we show that within the paraxial approximation the Fresnel number of the atomic ensemble and the optical depth are the only important physical parameters determining the quality of the quantum memory. We analyze the influence of these parameters on the storage of light followed by either forward or backward read-out from the quantum memory. We show that for small Fresnel numbers, the forward memory provides higher efficiencies, whereas for large Fresnel numbers, the backward memory is advantageous. The optimal light modes to store in the memory are presented together with the corresponding spin-waves and outcoming light modes. We show that for high optical depths such Lambda-type atomic ensembles allow for highly efficient backward and forward memories even for small Fresnel numbers $F\gtrsim 0.1$. Final version, 19 pages, 11 figures |
| Databáze: | OpenAIRE |
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