Quantum Institute: Visitor Schedule

The Quantum Lunch is regularly held on Thursdays in the Theoretical Division Conference Room, TA-3, Building 123, Room 121.
For more information, contact Diego Dalvit.

September 29, 2006
12:30 PM

Oliver Pfister,
University of Virginia

Sub-shot-noise interferometry with correlated photon numbers: who needs indistinguishability?

Abstract

As is well known in classical physics, interference is a phenomenon specific to waves. When considering the phase sensitivity limit of an interferometer, however, one must consider the quantum nature of the system, which brings in the flip side of the coin, the particle nature of the system whose De Broglie wave is interfering. Indeed, it is the quantum particle (photon, in our case) statistics of the interferometer that determine its ultimate performance. Ways to manipulate those statistics, in order to obtain a sensitivity improvement beyond the shot noise limit of the beam splitter, were first proposed in 1981 by Caves, with squeezed states, and successfully demonstrated in 1987 by the groups of Kimble and Slusher. In this talk, I will present recent experimental realizations of sub-shot-noise interferometry based on the photon-number-correlated light beams emitted above threshold by an ultrastable optical parametric oscillator. The basic physical effect is Fock-state quantum interference that is a generalization of the well known Hong-Ou-Mandel effect at a balanced beam splitter. Recently, we have obtained a record noise reduction of -4.8 dB in a heterodyne polarimetry experiment. I will also point out some fairly counterintuitive subtleties related to squeezing detection and distinguishability.