Demonstrating backflow in classical two beam’s interference

by Dr. Anat Daniel

University of Warsaw

at Quantum optics seminar

Wed, 07 Jun 2023, 16:00
ZOOM only

Abstract

Zoom link: https://us02web.zoom.us/j/86850073732

Abstract:
Backflow is a counterintuitive phenomenon that appears in optics (retro-propagating light) and in quantum mechanics. It occurs when the local oscillation of a superposition state is faster than its fastest Fourier component (also known as super (or sub) oscillations) .
In this presentation, I will begin with a brief overview of quantum backflow, and then proceed to our experimental demonstration of the equivalence in optics. In particular, we examine the interference of two Gaussian beams with unequal amplitudes and show that within the wavy wavefront of such a superposition, there are regions where anomalous local phase gradients appear [1]. This is what we certify as optical backflow in the transverse linear momentum. Furthermore, building upon our previous study, we extend our exploration to the interference of light solely carrying negative orbital angular momentum. Remarkably, we observe the manifestation of positive local orbital angular momentum within the dark fringes, providing experimental evidence for what we refer to as azimuthal backflow [2].
[1] Anat Daniel et al 2022 New J. Phys. 24 123011
[2] arXiv:2304.13124 , Azimuthal backflow in light carrying orbital angular momentum – in peer review.

Created on 04-06-2023 by Folman, Ron (folman)
Updaded on 04-06-2023 by Folman, Ron (folman)