Quantum interface between frequency-uncorrelated down-converted entanglement and atomic-ensemble quantum memory
arXiv:1004.4691
Abstract
Photonic entanglement source and quantum memory are two basic building blocks of linear-optical quantum computation and long-distance quantum communication. In the past decades, intensive researches have been carried out, and remarkable progress, particularly based on the spontaneous parametric down-converted (SPDC) entanglement source and atomic ensembles, has been achieved. Currently, an important task towards scalable quantum information processing (QIP) is to efficiently write and read entanglement generated from a SPDC source into and out of an atomic quantum memory. Here we report the first experimental realization of a quantum interface by building a 5 MHz frequency-uncorrelated SPDC source and reversibly mapping the generated entangled photons into and out of a remote optically thick cold atomic memory using electromagnetically induced transparency. The frequency correlation between the entangled photons is almost fully eliminated with a suitable pump pulse. The storage of a triggered single photon with arbitrary polarization is shown to reach an average fidelity of 92% for 200 ns storage time. Moreover, polarization-entangled photon pairs are prepared, and one of photons is stored in the atomic memory while the other keeps flying. The CHSH Bell's inequality is measured and violation is clearly observed for storage time up to 1 microsecond. This demonstrates the entanglement is stored and survives during the storage. Our work establishes a crucial element to implement scalable all-optical QIP, and thus presents a substantial progress in quantum information science.
28 pages, 4 figures, 1 table
References in corpus (13)
- Experimental demonstration of quantum memory for light
- Experimental entanglement of six photons in graph states
- Mapping photonic entanglement into and out of a quantum memory
- Experimental demonstration of a BDCZ quantum repeater node
- Entangling Independent Photons by Time Measurement
- Experimental entanglement of a six-photon symmetric Dicke state
- A millisecond quantum memory for scalable quantum networks
- How good must single photon sources and detectors be for efficient linear optical quantum computation?
- Experimental Quantum Teleportation of a Two-Qubit Composite System
- A Robust Atom-Photon Entanglement Source for Quantum Repeaters
- Time-bin modulated polarization-entangled biphotons from cavity-enhanced down-conversion
- Scalable Generation of Graph-State Entanglement through Realistic Linear Optics
- Experimental Quantum Teleportation and Multi-Photon Entanglement via Interfering Narrowband Photon Sources