Absorbers as detectors for unbound quantum systems

Complex absorbing potentials are frequently employed in quantum calculations. One of the advantages that such absorbers provide is ability to attenuate outgoing waves simulations unbound systems, thus allowing for truncating numerical domain. Here we argue absorber may also be used probe so physical information about absorbed particles retained. Moreover, under certain conditions, extracted via subject loss coherence, as case when collapsing wave function upon measurement. Both these aspects demonstrate clearly how, and when, effect introducing a complex potential corresponds detector.