Comparing the information capacity of Laguerre–Gaussian and Hermite–Gaussian modal sets in a finite-aperture system

Using a spontaneous parametric down-conversion process to create entangled spatial states, we compare the information capacity associated with measurements in the Hermite–Gaussian and Laguerre–Gaussian modal basis in an optical system of finite aperture. We show that the cross-talk imposed by the aperture restriction degrades the information capacity. However, the Laguerre–Gaussian mode measurements show greater resilience to cross talk than the Hermite–Gaussian, suggesting that the Laguerre–Gaussian modal set may still offer real-world advantages over other modal sets.