Physics Colloquium, "Quantum Ghosts Go Bump in the Night"by Dr. David Cyganski, WPI ECE Department

Science / Technology - Colloquium

Monday, April 2, 2012
4:00 PM-5:00 PM

Olin Hall
107

A rather remarkable non-classical effect was first identified by Elitzur and Vaidman in 1993 in which the presence of a perfectly photon absorbing object could, with some probability be detected without absorbing the probe photon. Experiments confirming this interaction-free measurement (IFM) were carried out and and the theory improved upon by Kwiat et al. in 1995. The improved scheme, sometimes called Quantum Seeing in the Dark (QSD,) since no photon illuminates the object which is probed, is based upon the quantum Zeno paradox and can in theory perform an IFM with probability of 1. Tantalizing applications include x-ray imaging without exposure and other forms of imaging of sensitive materials.

In this talk we will describe our novel counterpoint to IFM, an Object Free Interaction (OFI). We will show that a quantum system can determine, with significant probability (and asymptotically with certainty for many tests), whether or not someone is trying to observe our system with an IFM system. In fact we will show that a photon-less, or dark probe, can non-trivially interact with another photon-less IFM probe - that is, two quantum ghosts can go bump in the photon-less night! The development will be motivated by an application to a problem of mythical proportions involving the need to detect an otherwise undetectable detector.

Refreshments will be served at 3:30 in Olin Hall 118

Cost: Free

Suggested Audiences: College

E-mail: physics@wpi.edu
Phone: 508-831-5258

Last Modified: March 27, 2012 at 8:38 AM

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