Quantum memory as a perpetuum mobile? Stability v.s. reversibility of information processing

It is argued using a Gedankenexperiment that a scalable quantum memory could be used as a perpetuum mobile of the second kind and hence cannot be realized in Nature. The reasoning is based on the assumption that the Landauer's principle for measurements is a consequence of the second law of thermodynamics and not an independent postulate. This implies a modification of the Landauer's principle when applied for discrimination of equilibrium (metastable) states. While identification of the metastable state can be done at the infinitesimally low cost, a change of such a state involves dissipation of energy proportional to its stability factor.