Azimuthal backflow in light carrying orbital angular momentum

Abstract:
“M.V. Berry’s work [J. Phys. A: Math. Theor. 43, 415302 (2010)] highlighted the correspondence between backflow in quantum mechanics and superoscillations in waves. Superoscillations refer to situations where the local oscillation of a superposition is faster than its fastest Fourier component. This concept has been used to demonstrate backflow in transverse linear momentum for optical waves. In this work, we examine the interference of classical light carrying only negative orbital angular momentum and observe in the dark fringes of such an interference, positive local orbital angular momentum. This finding may have implications for the studies of light-matter interaction and represents a step towards observing quantum backflow in two dimensions.”