Quantum communication

Current research on quantum communication is motivated by the need for encryption methods which cannot be broken by quantum computers, contrary to classical encryption. The development of quantum networks could lead to applications such as enhanced sensor networks or distributed quantum computing. To enable communications over large distances, quantum networks require the presence of quantum repeaters, allowing the distribution of quantum states and information between entities without direct point-to-point connections.

The QST division at Imo-Imomec studies the development of quantum memories that could be used as outer nodes for quantum communication networks. We investigate in particular memories based on NV centres in diamond, presenting the longest memory coherence properties at room temperature and for which we already established the photoelectric readout of a single nuclear spin coupled to an NV electron spin. However, other point defects in diamond - in particular group IV-vacancy defects, presenting better optical properties  - are also considered for this application.

Another axis of our work deals with ultra-low-noise light detection methods, for application in the field of gravitational waves detection. Theoretical studies aiming at the mathematical description of light quantum detection (in particular squeezing and entanglement-based method) are performed, and an experimental setup enabling the production of squeezed light and the heterodyne detection of light is developed. We investigate in particular the suppression of quantum noise by using spin-optomechanical hybrid systems based on ensembles of nuclear spins in diamond.