  We test Boltzmann's H-theorem for several models of particle random walk. We
study the influence of interaction between the particle and reservoir/detectors
on entropy and find entropy increasing in time for some models and behaving
non-monotonically for others. The key mechanism affecting the entropy growth is
the quantum entanglement between the system and the reservoir. We discuss the
details of the system-reservoir interaction, such as presence of the
interference in the system and number of interactions with detector parts, and
their impact on the monotonicity of entropy.
