2017-11-20 - Ore 14:30 - Aula 1G09
"Can [optical device]n perform [seemingly unphysical task]n?"
Speaker: Prof. Miguel A. Alonso, Institute of Optics, University of Rochester
Proponent: B. Piccirillo e prof. L. Marrucci
It will be described three separate situations (so n in the title runs from 1 to 3) in which a simple optical device or configuration appears to be able to perform a physically surprising effect. All three situations have caused some level of controversy in the literature (with articles, comments to articles, replies to comments to articles, ...). The first situation deals with whether a monochromatic wave can gain intensity after being totally internally reflected from a gain medium (its Fresnel reflection being larger than unity). The second addresses the question of whether perfect resolution below the diffraction limit is achievable through what is known as "absolute systems", in particular a variant of the Maxwell fisheye lens proposed by Shafer. The third discusses whether one can tell "the past of a photon" and change this past by using a simple Dove prism. Spoiler alert: in all cases common sense prevails (or does it?) even though there are interesting subtleties related to boundary conditions, convergence of series, branch cuts, evanescent waves, wave propagators, modes, and basic interference.