Diffusion effects in gradient echo memory

Luo, Xisheng; Hope, Joseph; Hillman, Ben; Stace, Thomas M.

doi:10.1103/physreva.87.062328

Cited by 14 publications

(25 citation statements)

References 30 publications

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“…Unlike the EIT polariton, the GEM polariton propagates in k-space at a velocity given by the frequency gradient η (1) [26,27], i.e. k SW (t) • ẑ = k 0 SW • ẑ + η (1) (t)t. The initial spatial frequency is given by k 0 SW = k p − k c where k p and k c are the k-vectors of the probe and control fields, respectively.…”

Section: Long-lifetime Single Mode Storagementioning

confidence: 99%

Highly efficient optical quantum memory with long coherence time in cold atoms

Cho

Campbell

Everett

et al. 2016

Optica

184

147

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Optical quantum memory is an essential element for long distance quantum communication and photonic quantum computation protocols. The practical implementation of such protocols requires an efficient quantum memory with long coherence time. Beating the no-cloning limit, for example, requires efficiencies above 50%. An ideal optical fibre loop has a loss of 50% in 100 µs, and until now no universal quantum memory has beaten this time-efficiency limit. Here, we report results of a gradient echo memory (GEM) experiment in a cold atomic ensemble with a 1/e coherence time up to 1 ms and maximum efficiency up to 87 ± 2% for short storage times. Our experimental data demonstrates greater than 50% efficiency for storage times up to 0.6 ms. Quantum storage ability is verified beyond the ideal fibre limit using heterodyne tomography of small coherent states.

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Section: Long-lifetime Single Mode Storagementioning

confidence: 99%

Highly efficient optical quantum memory with long coherence time in cold atoms

Cho

Campbell

Everett

et al. 2016

Optica

184

147

View full text Add to dashboard Cite

show abstract

“…There is a number of currently developing systems where diffusion is the main limitation. An important example of such a system is storing and retrieving transverse modes and images in gradient echo memory [7][8][9][10], in collective Raman scattering [11] or in EIT [12]. Typically diffusional motion of atoms in a buffer gas limits the storage time [13,14], restricts the number of spatial modes retrieved [11] or broadens the EIT spectrum [15].…”

Section: Introductionmentioning

confidence: 99%

How to measure diffusional decoherence in multimode rubidium vapor memories?

Chrapkiewicz

Wasilewski

Radzewicz

2014

Optics Communications

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Diffusion is the main limitation of storage time in spatially multimode applications of warm atomic vapors. Precise knowledge of diffusional decoherence in the system is desired for designing most of vapor memory setups. Here we present a novel, efficient and direct method of measuring unbiased diffusional decoherence, clearly distinguished from all other decoherence sources. We found the normalized diffusion coefficients of rubidium atoms in noble gases to be as follows: neon 0.20 cm 2 /s, krypton 0.068 cm 2 /s and we are the first to give an experimental result for rubidium in xenon: 0.057 cm 2 /s. Our method consists in creating, storing and retrieving spatially-varying atomic coherence. Raman scattering provides a necessary interface to the atoms that allows for probing many spatial periodicities of atomic coherence concurrently. As opposed to previous experiments the method can be used for any single sealed glass cell and it does not require any setup alterations during the measurements and therefore it is robust and repeatable.

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“…In all of the above examples the diffusion rate was among primary performance limiting factors. Its importance has been recognized and its effect on EIT [8][9][10][11] and on the Gradient Echo Memory [12][13][14] have been studied both experimentally and theoretically.…”

Section: Introductionmentioning

confidence: 99%

Direct observation of atomic diffusion in warm rubidium ensembles

Parniak

Wasilewski

2013

Appl. Phys. B

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We present a robust method for measuring diffusion coefficients of warm atoms in buffer gases. Using optical pumping, we manipulate the atomic spin in a thin cylinder inside the cell. Then, we observe the spatial spread of optically pumped atoms in time using a camera, which allows us to determine the diffusion coefficient. As an example, we demonstrate measurements of diffusion coefficients of rubidium in neon, krypton and xenon acting as buffer gases. We have determined the normalized (273 K, 760 Torr) diffusion coefficients to be 0.18 ± 0.03 cm 2 /s for neon, 0.07 ± 0.01 cm 2 /s for krypton and 0.052 ± 0.006 cm 2 /s for xenon.

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Diffusion effects in gradient echo memory

Cited by 14 publications

References 30 publications

Highly efficient optical quantum memory with long coherence time in cold atoms

Highly efficient optical quantum memory with long coherence time in cold atoms

How to measure diffusional decoherence in multimode rubidium vapor memories?

Direct observation of atomic diffusion in warm rubidium ensembles

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