Maxwell's demon as a self-contained, information-powered refrigerator

January 12, 2016
An autonomous Maxwell's demon. When the demon sees the electron enter the island (1.), it traps the electron with a positive charge (2.). When the electron leaves the island (3.), the demon switches back a negative charge (4.). Credit: Jonne Koski

In 1867, Scottish physicist James Clerk Maxwell challenged the second law of thermodynamics according to which entropy in a closed system must always increase. In his thought experiment, Maxwell took a closed gas container, divided it into two parts with an inner wall and provided the wall with a small trap door. By opening and closing the door, the creature – 'demon' – controlling it could separate slow cold and fast warm particles to their respective sides, thus creating a temperature difference in contravention of the laws of thermodynamics.

On theoretical level, the has been an object of consideration for nearly 150 years, but testing it experimentally has been impossible until the last few years. Making use of nanotechnology, scientists from Aalto University have now succeeded in constructing an autonomous Maxwell's demon that makes it possible to analyse the microscopic changes in thermodynamics. The research results were recently published in Physical Review Letters. The work is part of the forthcoming PhD thesis of MSc Jonne Koski at Aalto University.

"The system we constructed is a single-electron transistor that is formed by a small metallic island connected to two leads by tunnel junctions made of superconducting materials. The demon connected to the system is also a single-electron transistor that monitors the movement of electrons in the system. When an electron tunnels to the island, the demon traps it with a positive charge. Conversely, when an electron leaves the island, the demon repels it with a negative charge and forces it to move uphill contrary to its potential, which lowers the temperature of the system," explains Professor Jukka Pekola.

What makes the demon autonomous or self-contained is that it performs the measurement and feedback operation without outside help. Changes in temperature are indicative of correlation between the demon and the system, or, in simple terms, of how much the demon 'knows' about the system. According to Pekola, the research would not have been possible without the Low Temperature Laboratory conditions.

"We work at extremely low temperatures, so the system is so well isolated that it is possible to register extremely small temperature changes," he says.

"An electronic demon also enables a very large number of repetitions of the measurement and feedback operation in a very short time, whereas those who, elsewhere in the world, used molecules to construct their demons had to contend with not more than a few hundred repetitions."

The work of the team led by Pekola remains, for the time being, basic research, but in the future, the results obtained may, among other things, pave the way towards reversible computing.

"As we work with superconducting circuits, it is also possible for us to create qubits of quantum computers. Next, we would like to examine these same phenomena on the quantum level," Pekola reveals.

Explore further: Study explains how Maxwell's demon uses mutual information to extract work

More information: J. V. Koski et al. On-Chip Maxwell's Demon as an Information-Powered Refrigerator, Physical Review Letters (2015). DOI: 10.1103/PhysRevLett.115.260602

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5 / 5 (3) Jan 12, 2016
And the result of the experiment was ......
5 / 5 (1) Jan 12, 2016
Maxwell's daemon classically controls the trap door in a barrier between two halves of a box creating an imbalance in the energy of particles on either side of the barrier. This appears to violate the second law of thermodynamics. The argument fails is when the nature of the daemon itself is considered. The daemon has to be able to make observations, make decisions based on the observations and take actions based on the decisions. How does it do this? Using energy. Where does the energy come from? Either the daemon is powered by taking energy away from the contents of the box or it was created with some internal power source. In the first case the energy required to cause the imbalance between the two halves of the box is taken from the contents of the box. In the second case the energy comes from the daemon. In either case the second law of thermodynamics is preserved if the total system, box plus daemon is considered.
Jan 12, 2016
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not rated yet Jan 12, 2016
Simple, charge complies to charge; therefore, seeks a steady state. However, we are dealing with a single revolver. Does all states settle to a single revolver? What if we have a system that does not lose energy? Anyway, this defines charge compliance. Opposite charges closer together and like charge farther apart, or simply repulsion moves away from each other and attraction moves closer together. Mobility in a field of a single charge revolver then limits closeness, i.e. is their a limit to how close atoms may be before instability. Or does the sun have two revolvers defining instability regions at the edge of the given regions. or ... but if you want to play with demons, play. Silly
not rated yet Jan 12, 2016
And the result of the experiment was ......

Second paragraph, page 4 of the paper here:

To summarize, they did measure an increase in entropy of the overall system.
not rated yet Jan 13, 2016
The above scheme could explain self-charging of electrets, http://dispatches...we.html.

Steorn's device and others like (there are multiples) it are manufactured via the creation of some very interestingly balanced alloy systems. They even have internal mechanical pressures at the lattice scale, due to the various materials in the mix.

The combination, if done right, becomes a very long lived trickle level of energy motion, and we can use it as a battery, until the stressing is relieved. Which will take many a year.

So yes, it is similar to what is done here, one might say. However, one does not directly proof the other.
Jan 13, 2016
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not rated yet Jan 17, 2016
It's a transistor, but at the subatomic particle scale. Maxwell's demon is the base.

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