  The quantum measurement problem is revisited and discussed in terms of a new
solvable measurement model which basic ingredient is the quantum model of a
controlled single-bit memory. The structure of this model involving strongly
coupled spin and quantum harmonic oscillator allows to define stable pointer
states as well-separated Gaussian states of the quantum oscillator and analyze
the transition from quantum to classical regime. The relations between accuracy
of measurement, stability of pointer states, effective temperature of joint
thermal and quantum noise and minimal work needed to perform the bit-flip are
derived. They differ from those based on the Landauer principle and are used to
analyze thermodynamic efficiency of quantum Szilard engine and imply more
realistic estimations of minimal amount of work needed to perform long
computations.
