Quantum Computation and Information Seminar 

14/02/2013, 15:00 — 16:00 — Room P3.10, Mathematics Building
Armando Nolasco Pinto, University of Aveiro & Instituto de Telecomunicações

Improving Fiber Optics Communication Systems Using Single-Photons

The ability to generate, manipulate, transmit and detect single-photons can open new routes that can trigger a complete new generation of optical communication systems. We show that quantum technologies can indeed address two of the more challenging problems that communication engineers face nowadays: capacity and security. We discuss critical issues in the implementation of quantum communication systems over installed optical fibers. We use stimulated four-wave mixing to generate single photons inside optical fibers, and by tuning the separation between the pump and the signal we adjust the average number of photons per pulse. We report measurements of the source statistics and show that it goes from a thermal to Poisson distribution with the increase of the pump power. We generate entangled photons pairs through spontaneous four-wave mixing. We present optimum configurations to increase the degree of entanglement. We discuss the impact of polarization rotation, attenuation and Raman scattering. We encode information in the photons polarization and discuss control methods to compensate for polarization random rotation during propagation. We discuss the implementation of single-photons systems in installed standard single-mode fibers.