The 6th edition of the Quantum Information Processing with Rare-Earth doped Solids meeting took place in Barcelona on May 12-13, 2011. This meeting has historically been central to the QuReP partners with the current QuReP project having been born out of these meetings. With many of the QuReP partners in attendance, the goal of the workshop was to bring together the main European groups working in the field (as well as some overseas guests), in order to discuss on going work, new ideas, experimental challenges and potential solutions.

This year's edition was organised by ICFO (in particular the Group of Prof. Hugues de Riedmatten) and supported by ICFO as well as the European project QuReP: Quantum Repeaters for Long-Distance Fiber-Based Quantum Communication.

The recent Winter School on Practical Quantum Cryptography was a huge success with a great mix of academics and industry people. An encouraging number of people (> 40%) were coming from outside the quantum communication community.

Professor Nicolas Gisin (Center) with Scholarship winners: Alessio Avella - Università degli Studi di Torino (left) and Sergii Strelchuk - University of Cambridge (right).

We have demonstrated that photons from entangled pairs can be stored in one of our quantum memories without losing the entanglement. This proves experimentally that the atomic frequency comb storage protocol developed at the GAP-Optique is indeed suited for the use in quantum repeaters. The results have now been published in Nature [1].

The results of the experiment are threefold. It demonstrates, for the first time, the successful storage of heralded single photons in a solid-state memory with storage-and-retrieval efficiencies surpassing 20% for the shortest storage time of 25ns. Additionally, we show that the non-classical nature of the intensity correlations between two photons in a pair are preserved after the storage and retrieval process, with storage times up to 200ns. Finally, a violation of a Bell inequality by more than three standard deviations proves that the storage process creates a light-matter entangled state. These results represent the first successful mapping of energy-time entangled photons onto a quantum memory, and we note that the intrinsic multimode capability makes the AFC perfectly suitable for storing this kind of entanglement.

1. C. Clausen et al., Nature Online (2011)

Also in the media:

An article (including comments by Mikael Afzelius and Wolfgang Tittel) in Physics World: Quantum communications boosted by solid memory devices