How Nonlocal Effects Alter Emission Spectra From Quantum Wells

Even the smallest electron orbit within a gallium arsenide quantum well, created by a magnetic field of a few Tesla, spans tens of nanometers, revealing an inherent “nonlocal” response to electromagnetic excitation. Researchers at Queen’s University and Technische Universität Berlin demonstrate that these nonlocal effects, stemming from the spatial dispersion of Landau levels, modify electromagnetic responses at distances up to hundreds of nanometers, a surprisingly large range for quantum phenomena. From a microscopic theory of the nonlocal susceptibility, they derive the Green’s function, the central quantity governing all electromagnetic interactions, and evaluate Purcell factors, Lamb shifts,…