Events Calendar

Decoherence of Polarization Entanglement in Optical Fibers With Polarization Mode Dispersion

Speaker: Misha Brodsky, AT&T Labs

Talk Title: Decoherence of Polarization Entanglement in Optical Fibers With Polarization Mode Dispersion

Abstract: Quantum mechanics permits the existence of unique correlations, or entanglement, between individual particles. For a pair of entangled photons, this means that performing a measurement on one photon appears to affect the state of the other. The ability of entangled particles to act in concert is preserved even when they are separated by large distances and serves as a resource for numerous applications. For example, distributing entangled photon pairs over fiber-optic cables enables secure communication between two remote parties or could offer the possibility of interconnecting quantum computers. The vast transparency band of the installed global fiber-optic network, consisting of over a Gigameter of optical fiber cables, presents a particularly attractive opportunity for this task. The bond between entangled photons is, however, very fragile and could be lost.

Several physical phenomena set limitations on transmission of classical light pulses through optical fibers. An intriguing and crucial question is how some of these well-studied phenomena, for instance Polarization Mode Dispersion (PMD), affect a polarization entangled photon pair. How far could one send entangled photons while still maintaining the connection between them?

We investigate, theoretically and experimentally, how inherent defects and miniscule imperfections in fiber-optic cables degrade entanglement between two photons transmitted over fibers. We show that the loss of entanglement could be either gradual or surprisingly abrupt. In addition, we suggest a novel way to compensate for adverse effects that occur during propagation in fibers. Finally, we define the range of fiber parameters over which entanglement remains sufficient for secure communication. The richness of the observed phenomena suggests that fiber-based entanglement distribution systems could serve as natural laboratories for studying entanglement decoherence.

A brief introduction to the topic of the talk is available on the front page of AT&T Labs website: www.research.att.com


Biography: Dr. Misha Brodsky joined AT&T Labs in 2000. His contributions to fiber optic communications focused on optical transmission systems and physics of fiber propagation, most notably through his work on polarization effects in fiber-optic networks. More recently Misha has been working on quantum communications; single photon detection; where his prime research interest is in photon entanglement and entanglement decoherence mechanisms in optical fibers.

Dr. Brodsky has authored or co-authored over 70 journal and conference papers, a book chapter and about two dozen patent applications. He is a topical editor for Optics Letters and has been active on numerous program committees for IEEE Photonics Society and OSA conferences. Dr. Brodsky holds a PhD in Physics from MIT.


Host: Daniel Lidar

Location: Hughes Aircraft Electrical Engineering Center (EEB) - 248

Audiences: Everyone Is Invited

Contact: Gerrielyn Ramos