Penn State scientists build quantum version of Maxwell’s demon

arstechnica.com

37 points·BerislavLopac··6 comments

For those who don't know, the term "daemon" as used in computing is a reference to Maxwell's demon, since it's doing its work in the background.

To be clear: No one is violating the 2nd law of thermodynamics here, nor is anyone trying. The scientists have a mechanism which reduces entropy at one part of a system at the expense of creating more entropy somewhere else. That mechanism could be useful in quantum computing.

Does this essentially make an equivalent of a refrigerator at a quantum scale?

My reading of this (and another article about it the other day), is that they haven’t constructed anything, just come up with a new experimental design that should theoretically be able to do it. Am I wrong?

> "His team used three pairs of laser beams to trap and cool neutral (uncharged) cesium atoms to ultra-cold temperatures (a few degrees above absolute zero) in a 3D lattice with 125 positions (a 5×5×5 cube). They filled half the positions with atoms in random positions and then moved the atoms around by changing the polarization of the laser traps—the equivalent function of Maxwell's demon, except using position to sort them rather than speed. By this means, they were able to create ordered 5×5×2 or 4×4×3 subsets within the originally disordered lattice, thereby reducing the system's entropy."

Quoting directly from the article, note I only skimmed it.

The article seems pretty clear that they did actually perform the experiment, not just design it.

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