Tunable delay of Einstein-Podolsky-Rosen entanglement

Entangled systems display correlations that are stronger than can be obtained classically. This makes entanglement an essential resource for a number of applications, such as quantum information processing, quantum computing and quantum communications. The ability to control the transfer of entangle...

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Bibliographic Details
Published in:Nature (London) 2009-02, Vol.457 (7231), p.859-862
Main Authors: Marino, A. M, Pooser, R. C, Boyer, V, Lett, P. D
Format: Article
Language:English
Subjects:
Atoms
Classical and quantum physics: mechanics and fields
Electromagnetic fields
Exact sciences and technology
Humanities and Social Sciences
letter
Light
multidisciplinary
Physics
Quantum communication
Quantum computing
Quantum information
Quantum theory
Science
Sensors
Signals and signaling
Variables
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Summary:Entangled systems display correlations that are stronger than can be obtained classically. This makes entanglement an essential resource for a number of applications, such as quantum information processing, quantum computing and quantum communications. The ability to control the transfer of entanglement between different locations will play a key role in these quantum protocols and enable quantum networks. Such a transfer requires a system that can delay quantum correlations without significant degradation, effectively acting as a short-term quantum memory. An important benchmark for such systems is the ability to delay Einstein-Podolsky-Rosen (EPR) levels of entanglement and to be able to tune the delay. EPR entanglement is the basis for a number of quantum protocols, allowing the remote inference of the properties of one system (to better than its standard quantum limit) through measurements on the other correlated system. Here we show that a four-wave mixing process based on a double-lambda scheme in hot 85Rb vapour allows us to obtain an optically tunable delay for EPR entangled beams of light. A significant maximum delay, of the order of the width of the cross-correlation function, is achieved. The four-wave mixing also preserves the quantum spatial correlations of the entangled beams. We take advantage of this property to delay entangled images, making this the first step towards a quantum memory for images.
ISSN:0028-0836
1476-4687
DOI:10.1038/nature07751