Community Research and Development Information Service - CORDIS

Quantum optics for quantum information processing

EU-funded scientists have worked on quantum memories – devices that enable the storage and on-demand retrieval of photons – to make it possible to synchronise the components of quantum information processors.
Quantum optics for quantum information processing
Quantum information processing with light is a tantalising possibility, but it requires the ability to implement logic gates at the single-photon level. Photons are charge-free and they do not interact directly. Therefore, for computations based on linear optical circuits, measurements are combined with probabilistic results to implement photon-photon interactions via post-selection.

This approach alone is not scalable to large devices, because for multiple logical gates the probability success falls with the size of the computation. Within the EU-funded project MEQUIP (Memory-enhanced photonic quantum information processing), researchers used memories for light to turn linear optical circuits into a scalable architecture for quantum computing.

Specifically, the MEQUIP team developed a number of tools and techniques that will allow surpassing the scaling obstacle. For large-scale quantum information processing to be possible, a strategy for temporal multiplexing is needed to select successful events actively. Quantum memories provided an efficient means through active synchronisation.

Researchers interfaced a gigahertz-bandwidth heralded single-photon source with a room-temperature Raman memory. They stored single photons and observed the influence of the input photon statistics on the retrieved light, which agreed with theoretical predictions. The preservation of the stored field's statistics was, however, limited by four-wave-mixing noise.

Beyond their role in synchronisation, researchers also investigated the potential for processing information directly in memories. They analysed the quantum interference of optical and material excitations during the memory operation. Advances made in understanding how quantum memories could be effectively used to scale probabilistic quantum routines open up new avenues for research.

Importantly, MEQUIP results laid the groundwork for new collaborative projects. These include the EU-funded QUCHIP project, where the use of quantum memories will be further explored, and the possibility for spectral multiplexing by the Networked Quantum Information Technologies (NQIT) hub.

Related information


Quantum information processing, quantum memories, photons, linear optical circuits, MEQUIP
Follow us on: RSS Facebook Twitter YouTube Managed by the EU Publications Office Top