Maxwell's demon is a thought experiment that explores the relationship between the second law of thermodynamics and information. It involves a hypothetical being capable of observing individual particles and selectively allowing them to pass through a partition in a way that seemingly violates the second law by reducing entropy.
If Maxwell's demon had a quantum computer, it would not inherently enable the reversal of entropy. While quantum computers offer certain computational advantages, including the potential to solve complex problems faster, they still operate within the bounds of physical laws, including the second law of thermodynamics.
The second law of thermodynamics states that in an isolated system, the entropy tends to increase or stay the same over time. Entropy can be locally decreased, but it must be compensated for by an increase elsewhere, ensuring that the overall entropy of the system and its surroundings does not decrease. This concept is known as the "compensation principle."
In the case of Maxwell's demon, even if it had a quantum computer with extraordinary computational abilities, it would still be subject to the laws of thermodynamics. Any reductions in entropy achieved by selectively allowing particles to pass through the partition would require energy expenditure and increase entropy elsewhere in the system, maintaining the overall balance.
Therefore, the presence of a quantum computer in Maxwell's demon does not fundamentally change the underlying principles of thermodynamics and entropy. The demon would still be subject to the same limitations in attempting to reverse entropy.