Optical quantum memory

• Published in: Nature photonics Vol. 3; no. 12; pp. 706 - 714
• Main Authors: Lvovsky, Alexander I, Sanders, Barry C, Tittel, Wolfgang
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.12.2009; Nature Publishing Group
• Subjects: Applied and Technical Physics; Atoms & subatomic particles; Classical and quantum physics: mechanics and fields; Communication; Effects of atomic coherence on propagation, absorption and amplification of light; Error correction & detection; Exact sciences and technology; Fundamental areas of phenomenology (including applications); Information processing; Information science; Optical memory (data storage); Optical transient phenomena: quantum beats, photon echo, free-induction decay, dephasings and revivals, optical nutation and self-induced transparency; Optics; Photonics; Physics; Physics and Astronomy; Quantum communication; Quantum computation; Quantum computing; Quantum information; Quantum optics; Quantum Physics; review-article; Quantum computing; Electromagnetically induced transparency; Photon echo; Quantum computer; Optical memory; Information processing; Quantum optics; Optical delay lines; Quantum information; Synchronization; Quantum memory; Quantum communication
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/nphoton.2009.231

Quantum memory is important for a range of application including quantum information processing, matching various processes within a quantum devices, as a tool to convert photons to photons-on-demand and for implementation of long-distance quantum communication using quantum repeaters. Here, state-of-the-art optical quantum memory is reviewed. Quantum memory is essential for the development of many devices in quantum information processing, including a synchronization tool that matches various processes within a quantum computer, an identity quantum gate that leaves any state unchanged, and a mechanism to convert heralded photons to on-demand photons. In addition to quantum computing, quantum memory will be instrumental for implementing long-distance quantum communication using quantum repeaters. The importance of this basic quantum gate is exemplified by the multitude of optical quantum memory mechanisms being studied, such as optical delay lines, cavities and electromagnetically induced transparency, as well as schemes that rely on photon echoes and the off-resonant Faraday interaction. Here, we report on state-of-the-art developments in the field of optical quantum memory, establish criteria for successful quantum memory and detail current performance levels.