Neal Oza
Electrical Engineering & Computer Science
Northwestern University
"Entangled Photon Polarimetry "
Optical quantum information processing holds promise of exponential speedups for certain computational problems, physically guaranteed cryptographic security, and classically impossible communications protocols [1]. In order to realize these next-generation technologies, however, existing quantum communications systems will need to be dramatically improved. Just as real-time classical polarimetry—the in-situ, complete characterization of an optical field’s polarization—has facilitated progress in nearly every branch of modern optics, a real-time system for entangled photon polarimetry—the in-situ, complete characterization of arbitrary two-photon states—would find immediate use in the fields of quantum communication and optical quantum information processing. Previous ultra-bright sources of entangled photons [2] have enabled quantum state characterizations with less than a second of data collection time, but many of these experiments have relied on the automated rotation of bulk waveplates, adding tens of seconds of overhead to every tomography. Here we report on the construction and characterization of a telecom-band entangled photon polarimeter, which we use—for the first time—to record a 3 frame-per-second live video of a two-photon state’s evolution from separability to entanglement. Furthermore, this system is capable of displaying an evolving quantum state in real time.
References
[1] M. A. Nielsen and I. L. Chuang, Quantum Computation and Quantum Information (Cambridge University Press, 2000).
[2] J. B. Altepeter, E. R. Jeffrey, and P. G. Kwiat, “Phase-compensated ultra-bright source of entangled photons", Opt. Exp. 13, p. 8951 (2005).
Prem Kumar
Electrical Engineering & Computer Science
Northwestern University
"Quantum Communication and Information Processing in Telecom Fibers"
We have developed a new technique for generating entangled photons directly in the fiber itself, dramatically improving the prospects for quantum communication applications in optical fiber networks. This technique utilizes the Kerr nonlinearity of optical fiber to produce quantum correlated photons through the spontaneous four-wave mixing process. The correlated photons can then be entangled in various ways by incorporating indistinguishable pathways in the four-wave mixing amplitude. I will review the status of this field by describing experiments that demonstrate the generation and distribution of quantum entanglement is wave-division multiplexed optical fiber systems. I will then present some results on utilizing such entanglement for quantum communications and information processing tasks. I will end by presenting some preliminary results on a newly developed resource for ultrafast low-loss switching of photonic entanglement in fiber-optic quantum communication networks.
Wednesday, April 21, 2010 at 12:00 PM
Room F235, Technological Institute
Refreshments are served at 11:30 PM
