  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.
