Abstract
We apply collective Raman scattering to create, store and retrieve spatially multimode light in warm rubidium-87 vapors. The light is created in a spontaneous Stokes scattering process. This is accompanied by the creation of counterpart collective excitations in the atomic ensemble - the spin waves. After a certain storage time we coherently convert the spin waves into the light in deterministic anti-Stokes scattering. The whole process can be regarded as a delayed four-wave mixing which produces pairs of correlated, delayed random images. Storage of higher order spatial modes up to microseconds is possible owing to usage of a buffer gas. We study the performance of the Raman scattering, storage and retrieval of collective excitations focusing on spatial effects and the influence of decoherence caused by diffusion of rubidium atoms in different buffer gases. We quantify the number of modes created and retrieved by analyzing statistical correlations of intensity fluctuations between portions of the light scattered in the far field.
Highlights
Room temperature atomic vapors are a popular medium for quantum information processing
Atoms can be placed in a paraffin coated cell without a buffer gas which they traverse multiple times during the interaction so that their quantum state is symmetric with respect to the permutations and within the Holstein-Primakoff approximation the cell holds a single bosonic mode [5]
The pulse duration was adjusted to produce comparable spin wave excitations for each buffer gas resulting in tw = 330 ns for 0.5 torr Krypton, tw = 500 ns for 1 torr Krypton and tw = 1.8 μs for 5 torr Neon
Summary
Room temperature atomic vapors are a popular medium for quantum information processing. Perhaps, they offer the simplest approach to quantum repeaters [1], quantum memory [2,3] and numerous other quantum-enhanced protocols possible with deterministic light-atom interface [4] and long-lived ground state coherence. Room temperature vapors can be effectively utilized in two distinct ways. Room temperature vapors can be a very effective four-wave mixing medium [10] and a source of spatially multimode squeezing [11] with a potential for quantum imaging [12]
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