Quantum Mechanics and Information: Experiments

Ultrafast Switching of Photonic Entanglement

aula DOTTORATO - venerdì 24 Settembre, ore 14.00
  PREM KUMAR , Department of Electrical and Computer Engineering and the Department of Physics and Astronomy at
Northwestern University and Center for Photonic Communication and Computing, Evanston, Illinois

Prem Kumar is the AT&T Professor of Information Technology in the EECS Department and Director of the Center for Photonic Communication and Computing at Northwestern University. He also holds an appointment as Professor of Physics and Astronomy. Prof. Kumar received a Ph.D. in physics from the State University of New York at Buffalo in 1980 and joined Northwestern in 1986 after spending five years at MIT as a research scientist. He is the author or co-author of numerous publications, including one edited book, one book chapter, six patents, over 170 papers in peer-reviewed journals, 45 articles in hard-bound volumes, and over 80 invited conference papers. His research focuses on the development of novel free-space and fiber-optic devices utilizing the principles of nonlinear and quantum optics. He is a fellow of the OSA, the APS, the IEEE, the IoP (UK), the AAAS, and the SPIE. In 2006 he received the Martin E. and Gertrude G. Walder Research Excellence Award from Northwestern University and in 2004 he received the 5th International Quantum Communication Award from the Tamagawa University in Tokyo, Japan. He was a Distinguished Lecturer for the IEEE Photonics Society from July 2008 to June 2010.

Prem Kumar

“Harnessing the existing telecommunications infrastructure to distribute entangled photons would provide a dramatic reduction in the overhead needed to deploy and operate a quantum network. The traditionally empty 1310-nm telecommunications band is uniquely suited for this task. However, an additional resource is required to realize such a network: a switch capable of routing single photons at high speeds, with minimal loss and signal-band noise, and-most importantly-without disturbing the photons' quantum state. These exacting requirements preclude the use of all previous switching technologies. In this talk I will present a switch that fulfills these requirements. We recently demonstrated such a switch and characterized its performance at the single photon level. It exhibits a 200-ps switching window, a 120:1 contrast ratio, < 1 dB loss, and induces no measurable degradation in the switched photons’ entangled-state fidelity (< 0.002). We also demonstrated its utility for quantum networks by successfully demultiplexing a single quantum channel from a dual-channel, time-division-multiplexed entangled photon stream [1].

[1] M. A. Hall, J. B. Altepeter, and P. Kumar, "Ultrafast Switching of Photonic Entanglement," submitted to Physical Review Letters. See arXiv: 1008.4879v1 [quant-ph] 28 Aug 2010;