ALACOQ: ALternative Architecture Combination for Optical Quantum storage

Project funded by French National Research Agency (ANR), grant ANR-07-BLAN-0273. Participating organisations named by the source: CENTRE NATIONAL DE LA RECHERCHE SCIENTIFIQUE - DELEGATION REGIONALE ILE-DE-FRANCE SECTEUR PARIS B; Univ Paris. Funded amount: EUR 260,000, as stated by the source. Runs 2007-11-08 to n/a. Source: OpenAIRE Graph, from the funder's project data (collected by OpenAIRE on 2026-07-23); national funding data, not CORDIS. Abstract given by the source: The storage and retrieval of a quantum state of light is expected to play a fundamental role in long distance quantum communication networks. The project is placed in this prospect. The core of the project is the investigation of storage architectures in atomic ensembles at the few-photon signal level. The systems to be considered are inhomogeneously broadened solid materials, more specifically, rare earth ion doped crystals. Those systems are known to exhibit long lifetime quantum superposition states. Quantum information storage and retrieval relies on contradictory requirements. The same medium should be opaque at storage and transparent at readout. This apparent paradox is solved with the help of intense driving fields that, conveniently and at will, modify the medium properties. With such protocols, relying on EIT (Electromagnetically Induced Transparency) one faces the problem of detecting a very weak signal against the background induced by strong driving fields. However this operating mode has been the most popular one in homogeneously broadened materials such as laser cooled atomic clouds. In inhomogeneously broadened materials, echo procedures may offer a way to temporally separate the weak signal from the intense driving pulses. They take advantage of atomic coherence deterministic dephasing and rephasing. We propose to explore this route at the few-photon level, a task that has not been undertaken yet. In addition to phase-reversing the atomic superposition state carrying the quantum information, the strong driving pulse simultaneously affects the atomic level population distribution. This may damage the retrieval fidelity. It has then been proposed to substitute optical driving with a reversible static electric field control. One proceeds along several steps. First a narrow spectral group of absorbing atoms is selected. Then appropriate electric field gradient is applied which, by way of Stark effect, gives rise to the desired inhomogeneous width. To [shortened; the full text is on the OpenAIRE page]

Original source.

Source: OpenAIRE Graph: projects of national funders, OpenAIRE, from the project data of French National Research Agency (ANR). Retrieved 2026-10-22. Licence: Creative Commons Attribution 4.0 (OpenAIRE Graph). Selected metadata, adapted presentation; the publisher's record is authoritative. No endorsement by the source is implied. Licence: Creative Commons Attribution 4.0 (CC BY 4.0).

AI-assisted summary: The ALACOQ project, funded by the French National Research Agency with EUR 260,000, investigates storage architectures for quantum states in atomic ensembles. It runs from 2007-11-08 and focuses on rare earth ion doped crystals for quantum communication. Suggested technology pillar: communication. Generated by AI from the public source text; it may contain errors and the original source is authoritative.