Project

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Highly coherent, powerful and compact yellow laser source for quantum memory

Applicant Gisin Nicolas
Number 139079
Funding scheme R'EQUIP
Research institution GAP-Optique Université de Genève
Institution of higher education University of Geneva - GE
Main discipline Other disciplines of Physics
Start/End 01.12.2011 - 30.11.2012
Approved amount 100'000.00
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Keywords (4)

quantum cryptography; quantum networks; stopping light; crystal memory

Lay Summary (English)

Lead
Lay summary

Modern society is increasingly reliant on information and with this comes increasing concerns for security of this information and its communication. Conventional cryptography relies on technological or mathematical assumptions for its security. Quantum key distribution technologies, however, do not make these assumptions and provide a means of distributing cryptographic keys that is provably secure. Today’s commercial quantum key distribution systems work up to about 100 km, but to go much further, new advanced technologies will have to be developed.

These new technologies will be based on networks of quantum communication systems where light propagating through optical fibers will be carrying the quantum information. These future quantum networks will require several new quantum devices to be developed. Among these are the quantum memories, which are devices able to store the fragile quantum information for later processing. In the Group of Applied Physics at Geneva University we work on developing quantum memories based on small optical crystals. These crystals can be used to effectively "stop" light for a short while and then to "release" the light again at a later moment. We have already obtained several important results with these crystals, which have been highlighted internationally. For our next generation of experiments we will need to invest in more sophisticated laser sources, financed in part by SNSF through this project. This will allow us to improve important features of our quantum memories, such as their efficiency performance and the duration during which the quantum information can be stored.


Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Collaboration

Group / person Country
Types of collaboration
Prof. Hugues de Riedmatten, The Institute of Photonic Sciences (ICFO), Barcelona Spain (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Dr. Philippe Goldner, CNRS, Chimie-Paristech, Paris France (Europe)
- in-depth/constructive exchanges on approaches, methods or results
Prof. Stefan Kröll, Lund University, Lund Sweden (Europe)
- in-depth/constructive exchanges on approaches, methods or results
QESSENCE EU PROJECT Belgium (Europe)
- in-depth/constructive exchanges on approaches, methods or results

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
International Conference on Quantum Communication, Measurement and Computing (QCMC) Talk given at a conference Quantum Communication 30.07.2012 Vienna, Austria, Austria Gisin Nicolas;
Cluster review meeting Talk given at a conference Solid state quantum memory for quantum repeaters 18.04.2012 Mainz, Germany, Germany Afzelius Mikael;


Associated projects

Number Title Start Funding scheme
125723 NCCR QSIT: Quantum Science and Technology (phase I) 01.01.2011 National Centres of Competence in Research (NCCRs)

Abstract

Modern society is increasingly reliant on information and with this comes increasing concerns for security of this information and its communication. Conventional cryptography relies on techno-logical or mathematical assumptions for its security. Quantum key distribution technologies, how-ever, do not make these assumptions and provide a means of distributing cryptographic keys that is provably secure [Gisin02]. Today’s Quantum key distribution systems use point-to-point architec-tures and dark fibres, with commercial systems available to cover 100km distances (www.idquantique.com), while laboratory versions are approaching 250km [Stucki09], which is almost at the practical limit. Novel schemes and advanced entanglement enabled technologies will be required for the next generation devices to surpass this current limitation.The solution to long-distance quantum communication is the quantum repeater, a theoretical concept proposed in 1998 [Briegel1998] and the analogue of fibre optical amplifiers that made global fibre communication feasible. A quantum repeater is an experimental challenge to the quantum information community and of major strategic importance to our information-based society. In this context our group is coordinating a European-wide research effort QuReP, develop-ing future hardware for quantum repeaters. A crucial component in a repeater is the quantum memory, which is a device that enables one to stop the entangled photons and to store them at fix locations. The memories act like nodes in a quantum network and they are crucial for the scalabil-ity of quantum communication based on entanglement and teleportation.In the European QuReP project and Swiss QSIT (Quantum Science and Technology) NCCR pro-gramme we work on quantum memories based on ensembles of ions in a solid-state matrix. More specifically, these are rare-earth-ion doped crystals which already in the past have played a crucial role in the development of compact solid-state lasers. Here we use their excellent coherence prop-erties in order to store quantum information. Since the beginning of this research in around 2004, we have achieved some of the most important milestones. For instance, in 2008 we achieved the first storage of pseudo single photons in a crystal [Riedmatten08]. In 2010 we demonstrated en-tanglement between a telecommunications photon and a photon stored in a neodymium-doped crystal [Clausen11]. Our results clearly show that these systems hold great promise for solid-state based quantum memories for quantum repeaters.To go beyond these achievements, we work since about 2 years on europium-doped materials, because these have truly impressive coherence properties. A technical difficulty using europium is the absorption wavelength at around 580 nm, since no commercial laser systems based on diode lasers were available until now. In late 2009 we thus built our own source based on commercial diode lasers and sum-frequency generation. Our initial results using this source are very promising [Lauritzen11], but the performance of the memory is limited by the low power, reduced coherence and long-term instabilities of our source. Now a commercial alternative has emerged, developed for artificial guide stars for astronomical telescopes. We would like to take advantage of this de-velopment by acquiring a commercial high-power, high-coherence and stable laser source. [Gisin02] N. Gisin, G. Ribordy, W. Tittel and H. Zbinden, Rev. Mod. Phys., 74, 145 (2002)[Stucki09] D Stucki, N Walenta, F Vannel, R T Thew, N Gisin, H Zbinden, S Gray, C R Towery, and S Ten, New Journal of Physics 11, 075003 (2009)[Briegel1998] H. Briegel, W. Duer, J.I. Cirac, and P. Zoller, Phys. Rev. Lett., 81, 5932 (1998)[Riedmatten08] H. de Riedmatten, M. Afzelius, M.U. Staudt, C. Simon, and N. Gisin, Nature, 456, 773 (2008)[Clausen11] C. Clausen, I. Usmani, F. Bussières, N. Sangouard, M. Afzelius, H. de Riedmatten, and N. Gisin, Nature 469, 508 (2011)[Lauritzen11] B. Lauritzen, N. Timoney, N. Gisin, and M. Afzelius, “Spectroscopic investigations of Eu3+:Y2SiO5 for quantum memory applications”, to be submitted
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