Abstract
We present the concept of nonreciprocal interferometers. These two-way devices let particles pass in both directions, but in one direction break the phase of the particles' wave functions. Such filters can be realized by using, for example, asymmetric quantum rings. Furthermore, we propose arrangements of these interferometers to obtain larger interferometers which are expected to exhibit a puzzling behavior that resembles Maxwell demon action. We indicate an opportunity to resolve this puzzle experimentally.