Testing Chameleon Fields with Ultra Cold Neutron Bound States and Neutron Interferometry

Chameleons can play a role in the recent acceleration of the expansion of the Universe. We present results where chameleon fields modify the terrestrial gravitational potential above a mirror and lead to a small perturbation of the energy levels of the neutrons in experimental setups such as GRANIT in Grenoble. With the current sensitivity, these experiments probe chameleon fields in a large coupling to matter regime. We also comment on the possibility of testing chameleon fields with neutron interferometry.