The temperature of an oscillator coupled to the vacuum state of a heat bath
via ohmic coupling is non-zero, as measured by the reduced density matrix of
the oscillator. This paper shows that the actual temperature, as measured by a
thermometer is still zero (or in the thermal state of the bath, the temperature
of the bath). The decoherence temperature is due to "false-decoherence", with
the heat bath state being dragged along with the oscillator.Comment: 6 page