Absorbers as detectors for unbound quantum systems

Complex absorbing potentials are frequently imposed when simulating unbound quantum systems. While this is usually done solely in order to avoid artifacts at the numerical boundary, we show how absorbers may also be used to probe the characteristics of the particle undergoing absorption. This way, information about the removed particles may be retained. Moreover, we explain how – and when – such absorbers act as detectors in the sense that they allow for simulating the act of measurement in dynamical simulations.