>PRESENTATION:
Prem Kumar is a Professor of Information Technology. He is the founder and Director of Center for Photonic Communication and Computing. Prior to Northwestern, he was a Staff Scientist at the MIT Lincoln Laboratory and a Research Scientist at the Research Laboratory of Electronics at MIT. Fellow of the Institute of Electrical and Electronic Engineers (IEEE), of the Optical Society of America (OSA), of the American Physical Society (APS), and of the Institute of Physics (IoP). Prem Kumar received his B.Sc. from the University of Delhi, Delhi, India, in 1974. He received his M.Sc. from the Indian Institute of Technology, Kanpur, India, in 1976. He received his Ph.D. from the State University of New York at Buffalo, in 1980. His research interests ranges in Optical communications, in particular, novel optical amplifiers and devices for terabits per second fiber-optic communications; quantum fiber-optics, in particular, generation and distribution of quantum entanglement over the fiber channel and quantum cryptography over fiber lines; nonlinear and quantum optics, in particular, applications of novel states of light such as squeezed and twin-beam states.

“Keeping in mind the ubiquitous standard optical fiber for long-distance transmission and the widespread availability of efficient active and passive fiber devices, we have been developing telecom-band resources for practical quantum communication and cryptography in wave-division-multiplexed (WDM) optical networks. In this talk I will present our recent results on two fronts: i) telecom-band in-fiber entanglement generation, storage, and long-distance distribution and ii) quantum-noise protected high-speed data encryption through an optically-amplified WDM line. Along the first front, with our in-fiber entanglement source we have demonstrated storage of entanglement for up to 1/8 millisecond. In addition, when each photon of the entangled pair is propagated in separate 25km-long standard fibers, high visibility quantum interference is still observed, demonstrating that this system is capable of long-distance (> 50 km) entanglement distribution. Along the second front, we have implemented a new quantum cryptographic scheme, based on Yuen’s KCQ protocol, in which the inherent quantum noise of coherent states of light is used to perform the cryptographic service of data encryption. In this scheme a legitimate receiver, with use of a short, shared, secret-key, executes a simple binary decision rule on every transmitted bit. An eavesdropper, on the other hand, who does not possess the secret-key, is subjected to an irreducible quantum uncertainty in each measurement, even with the use of ideal detectors. A practical data encryption system has been demonstrated for WDM networks using off-the-shelf components at a data rate of 622 Mbps (OC-12 rate). Technology developed under this project has been successfully transferred to industry and is being tested in realistic networking environments.”