Minimal temperature of quantum refrigerators

A first-principle reciprocating quantum refrigerator is investigated to determine the limitations of cooling to absolute zero. If the energy spectrum of the working medium possesses an uncontrollable gap, then there is a minimum achievable temperature above zero. Such a gap, combined with a negligible amount of noise, prevents adiabatic following during the expansion stage which is the necessary condition for reaching T-c -> 0. Copyright (C) EPLA, 2010