  Thermodynamics dictates that the specific heat of a system is strictly
non-negative. However, in finite classical systems there are well known
theoretical and experimental cases where this rule is violated, in particular
finite atomic clusters. Here, we show for the first time that negative heat
capacity can also occur in finite quantum systems. The physical scenario on
which this effect might be experimentally observed is discussed. Observing such
an effect might lead to the design of new light harvesting nano devices, in
particular a solar nano refrigerator.
