Tag Archives: unifying theory of electricity magnetism optics

Constructing an autonomous Maxwell’s demon as a self-contained information-powered refrigerator

Aalto University (Finland) was the lead research institution for  INFERNOS, a European Union-funded project concerning Maxwell’s demon. Here’s an excerpt from an Oct. 14, 2013 post featuring the project,

An Oct. 9, 2013 news item on Nanowerk ties together INFERNOS and the ‘demon’,

Maxwell’s Demon is an imaginary creature that the mathematician James Clerk Maxwell created in 1897. The creature could turn heat into work without causing any other change, which violates the second law of thermodynamics. The primary goal of the European project INFERNOS (Information, fluctuations, and energy control in small systems) is to realize experimentally Maxwell’s Demon; in other words, to develop the electronic and biomolecular nanodevices that support this principle.

I like the INFERNOS logo, demon and all,

Logo of the European project INFERNOS (Information, fluctuations, and energy control in small systems).

A Jan. 11, 2016 news item on Nanowerk seems to be highlighting a paper resulting from the INFERNOS project (Note: A link has been removed),

On [a] theoretical level, the thought experiment 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 (“On-Chip Maxwell’s Demon as an Information-Powered Refrigerator”). The work is part of the forthcoming PhD thesis of MSc Jonne Koski at Aalto University.

An image illustrating the theory underlying the proposed device has been made available,

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.). Image: Jonne Koski.

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.). Image: Jonne Koski.

A Jan. 11, 2016 Aalto University press release, which originated the news item, provides more technical details,

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.

Here’s a link to and a citation for the paper,

On-Chip Maxwell’s Demon as an Information-Powered Refrigerator by J.V. Koski, A. Kutvonen, I.M. Khaymovich, T. Ala-Nissila, and J.P. Pekola. Phys. Rev. Lett. 115, 260602 DOI: http://dx.doi.org/10.1103/PhysRevLett.115.260602 Published 30 December 2015

This paper is behind a paywall.

One final comment, this is the 150th anniversary of Maxwell’s publication of a series of equations explaining the relationships between electric charges and electric and magnetic fields (featured here in a Nov. 27, 2015 posting).

James Clerk Maxwell and his science mashup unified theories of magnetism, electricity, and optics

It’s the 150th anniversary for a series of equations electric charges and electric and magnetic fields that are still being explored. Jon Butterworth in a Nov. 22, 2015 posting on the Guardian science blog network explains (Note: A link has been removed),

The chances are that you are reading this article on some kind of electronic technology. You are definitely seeing it via visible light, unless you have a braille or audio converter. And it probably got to you via wifi or a mobile phone signal. All of those things are understood in terms of the relationships between electric charges and electric and magnetic fields summarised in Maxwell’s [James Clerk Maxwell] equations, published by the Royal Society in 1865, 150 years ago.

Verbally, the equations can be summarised as something like:

Electric and magnetic fields make electric charges move. Electric charges cause electric fields, but there are no magnetic charges. Changes in magnetic fields cause electric fields, and vice versa.

The equations specify precisely how it all happens, but that is the gist of it.

Butterworth got a rare opportunity to see the original manuscript,

 Original manuscript of Maxwell’s seminal paper Photograph: Jon Butterworth/Royal Society [downloaded from http://www.theguardian.com/science/life-and-physics/2015/nov/22/maxwells-equations-150-years-of-light]

Original manuscript of Maxwell’s seminal paper Photograph: Jon Butterworth/Royal Society [downloaded from http://www.theguardian.com/science/life-and-physics/2015/nov/22/maxwells-equations-150-years-of-light]

I love this description from Butterworth,

It was submitted in 1864 but, in a situation familiar to scientists everywhere, was held up in peer review. There’s a letter, dated March 1865, from William Thomson (later Lord Kelvin) saying he was sorry for being slow, that he’d read most of it and it seemed pretty good (“decidely suitable for publication”).

Then, there’s this,

The equations seem to have been very much a bottom-up affair, in that Maxwell collected together a number of known laws which were used to describe various experimental results, and (with a little extra ingredient of his own) fitted them into a unified framework. What is amazing is how much that framework then reveals, both in terms of deep physical principles, and rich physical phenomena.

I’m not excerpting any part of Butterworth’s description of how Maxwell fit these equations together for his unification theory as I think it should be read in its totality.

The section on quantum mechanics is surprising,

Now, one thing Maxwell’s equations don’t contain is quantum mechanics [emphasis mine]. They are classical equations. But if you take the quantum mechnical description of an electron, and you enforce the same charge conservation law/voltage symmetry that was contained in the classical Maxwell’s equations, something marvellous happens [emphasis mine]. The symmetry is denoted “U(1)”, and if you enforce it locally – that it, you say that you have to be allowed make different U(1) type changes to electrons at different points in space, you actually generate the quantum mechanical version of Maxwell’s equations out of nowhere [emphasis mine]. You produce the equations that describe the photon, and the whole of quantum electrodynamics.

I encourage you to read Butterworth’s Nov. 22, 2015 posting where he also mention two related art/science projects and has embedded a video animation of the principles discussed in his posting.

For anyone unfamiliar with Butterworth, there’s this description at the Guardian,

Jon Butterworth is a physics professor at University College London. He is a member of the UCL High Energy Physics group and works on the Atlas experiment at Cern’s Large Hadron Collider. His book Smashing Physics: The Inside Story of the Hunt for the Higgs was published in May 2014