Theoretical analysis of quantum random walks with stress-engineered optics

Quantum random walks (QRWs) are random processes in which the resulting probability density of the "walker" state, whose movement is governed by a "coin" state, is described in a non-classical manner. Previously, Q-plates have been used to demonstrate QRWs with polarization and orbital angular momentum playing the role of coin and walker states, respectively. In this theoretical analysis, we show how stress-engineered optics can be used to develop new platforms for complex QRWs through relative simple optical elements. Our work opens up new paths to speed up classical-to-quantum transitions in robust photonic networks

V2_polmaps.avi

Polarization map computed after propagating through a stress-engineered optic (SEO) at angles 0 through 24 degrees. The ellipses are overlaid on the intensity pattern after the beam goes through the circular analyzer, which blocks the RHC polarized light. The handedness of each polarization ellipse is color coded (green: right handed, red: left handed). Bottom panel illustrates the contour lines of equal ellipticity overlaid on the color coded azimuthal angle of each polarization ellipse on the Poincaré sphere

v1_comparison_contours.avi

Comparison between irradiance patterns from experimental images and the simulations involving oblique propagation of light through stress-engineered optic (SEO). The irradiance contour lines obtained from the numerical method have been overlaid on both the corresponding simulated image and the measured image