  We present a new optical scheme enabling the implementation of highly stable
and configurable non-Markovian dynamics. Here one photon qubit can circulate in
a multipass bulk geometry consisting of two concatenated Sagnac interferometers
to simulate the so called collisional model, where the system interacts at
discrete times with a vacuum environment. We show the optical features of our
apparatus and three different implementations of it, replicating a pure
Markovian scenario and two non-Markovian ones, where we quantify the
information backflow by tracking the evolution of the initial entanglement
between the system photon and an ancillary one.
