Title: Quantum Wavelength Division Multiplexing: a promising route to large scale quantum information processing

Abstract: Wavelength Division Multiplexing (WDM) is well known to have revolutionized, together with the use of optical fibers, the transmission and processing of classical information. It is at the basis of the tremendous development of our present World Wide Web. Its extension to the domain of Quantum Information Processing is an active subject of research because of its high potentialities in terms of scalability and capacity. On the other hand, mode-locked sources of ultra-short pulses, also called "optical frequency combs", provide a way to manipulate in a coherent way a great number of frequency modes. They are good candidates to generate quantum-coherent ensembles of frequency modes, and therefore to produce the high degree of entanglement required for useful applications in Quantum Computing. 

We have developed a parametrically generated mode locked light source that produces a highly multimode entangled quantum state of light.  We have demonstrated its embedded multipartite entanglement using pulse shaping techniques imported from coherent control. This fully characterized quantum object is easily addressable and “contains” cluster states of different topologies that are revealed by the measurement strategy. Such cluster states are the basis of a new way (called "measurement based quantum computing") of implementing quantum computing tasks. 

The generation of such a "quantum frequency comb" is a first step in the direction of Quantum Information Processing and Computing using Quantum Wave Division Multiplexing. It appears as a promising route to quantum computing because of its easy scalability to much higher node numbers and its robustness to decoherence.

Please Note:  Before the Colloquium, there is a common dinner in the canteen located on the ground floor of the Oort building. This dinner starts at 18:00 hours sharp and is free of charge, under the condition that one attends the colloquium and that one has made a reservation before noon on the Tuesday preceding the colloquium. The registration form is only accessible from within the University (to block spammers); if you would like to register for the dinner from outside the University, please send an email to fran@lorentz.leidenuniv.nl

The revolving doors of the Oort building, alongside the Kamerlingh Onnes Laboratory, are accessible until 9 pm after that one should instead use the sliding doors directly adjacent to the Huygens building: these can be opened with an electronic key (seek help from locals).The Colloquium Ehrenfestii lecture starts at 19:30 hours and will be held in the Sitterzaal.