University of Toronto
Physics Department
Quantum Optics and Condensed Matter

Abstract

How long does tunneling take? This question has been controversial since the 1930s, and the past decade has seen a spate of new work on the issue, teaching us primarily that we aren't even sure how to define the question. Recently, however, a number of experimental tests have become possible, and I will describe an experiment in which we used photon "twins" to measure the group delay for single-photon wave packets to tunnel through a mirror functioning as a 1D photonic bandgap. Agreement with the stationary phase approximation was better than 1 fs, even in the regime where transmission appears to be superluminal.

I will discuss interpretation of this faster-than-light light, and also present a theory based on Aharonov and Vaidman's ideas of "weak measurement," attempting to unify a number of theoretical proposals for the tunneling time. The new proposal suggests that it may be possible to say more about the "history" of quantum-mechanical particles than conventional wisdom would have us believe. An experiment is being built to observe quantum tunneling of atoms, a case in which the theory will be amenable to direct test.

Contact: Prof. Aephraim Steinberg (416-978-0713)