Three-dimensional theory of quantum memories based on {Lambda}-type atomic ensembles

Journal Article · Sat Oct 15 04:00:00 EDT 2011 · Physical Review. A

DOI:https://doi.org/10.1103/PHYSREVA.84.043838· OSTI ID:22093394

Zeuthen, Emil; Grodecka-Grad, Anna; Soerensen, Anders S. ^[1]

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1. QUANTOP, Danish National Research Foundation Center for Quantum Optics, Niels Bohr Institute, University of Copenhagen, DK-2100 Copenhagen O (Denmark)

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(greater-or-similar sign)0.1.

• OSTI ID: 22093394
• Journal Information: Physical Review. A, Journal Name: Physical Review. A Journal Issue: 4 Vol. 84; ISSN 1050-2947; ISSN PLRAAN
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
APPROXIMATIONS
ATOMS
EFFICIENCY
GROUND STATES
MEMORY DEVICES
SPIN WAVES
THREE-DIMENSIONAL CALCULATIONS
VISIBLE RADIATION