Giant quantum freezing of nanojunctions mediated by the environment

We investigate the quantum heat exchange between a nanojunction and a many-body or electromagnetic environment far from equilibrium. It is shown that the two-temperature energy emission-absorption mechanism gives rise to a giant heat flow between the junction and the environment. We obtain analytical results for the heat flow in an idealized high-impedance environment, perform numerical calculations for the general case of interacting electrons, and discuss giant freezing and heating effects in the junction under typical experimental conditions.