  We proposed the finite-time cycle model of a measurement-based quantum
cooler, where invasive measurement provides the power to drive the cooling
cycle. Such a cooler may be regarded as an alternative thought experiment of
Mawell's demon. The measurement-feedback information is capable of moving heat
from the cold to hot bath without any work input and even making the maximum
coefficient of performance larger than the Carnot limit. The causes that this
seemingly paradoxical result does not violate the laws of thermodynamics can be
clearly explained through the derivation of a generalized Clausius inequality
including the mutual information.
