Tag Archives: 2nd law of thermodynamics

Violating the 2nd law of thermodynamics—temporarily—at the nanoscale

For anyone unfamiliar with the laws of thermodynamics or anyone who enjoys some satire with their music, here’s the duo of Flanders & Swann with the ‘First and Second Law’ in a 1964 performance,

According to a March 31, 2014 news item on Nanowerk, it seems, contrary to scientific thought and Flanders & Swann, the 2nd law can be violated, for a time, albeit at the nanoscale,

Objects with sizes in the nanometer range, such as the molecular building blocks of living cells or nanotechnological devices, are continuously exposed to random collisions with surrounding molecules. In such fluctuating environments the fundamental laws of thermodynamics that govern our macroscopic world need to be rewritten. An international team of researchers from Barcelona, Zurich and Vienna found that a nanoparticle trapped with laser light temporarily violates the famous second law of thermodynamics, something that is impossible on human time and length scale.

A March 31, 2014 University of Vienna news release on EurekAlert, which originated the news item, describes the 2nd law and gives details about the research,

Watching a movie played in reverse often makes us laugh because unexpected and mysterious things seem to happen: glass shards lying on the floor slowly start to move towards each other, magically assemble and suddenly an intact glass jumps on the table where it gently gets to a halt. Or snow starts to from a water puddle in the sun, steadily growing until an entire snowman appears as if molded by an invisible hand. When we see such scenes, we immediately realize that according to our everyday experience something is out of the ordinary. Indeed, there are many processes in nature that can never be reversed. The physical law that captures this behavior is the celebrated second law of thermodynamics, which posits that the entropy of a system – a measure for the disorder of a system – never decreases spontaneously, thus favoring disorder (high entropy) over order (low entropy).

However, when we zoom into the microscopic world of atoms and molecules, this law softens up and looses its absolute strictness. Indeed, at the nanoscale the second law can be fleetingly violated. On rare occasions, one may observe events that never happen on the macroscopic scale such as, for example heat transfer from cold to hot which is unheard of in our daily lives. Although on average the second law of thermodynamics remains valid even in nanoscale systems, scientists are intrigued by these rare events and are investigating the meaning of irreversibility at the nanoscale.

Recently, a team of physicists of the University of Vienna, the Institute of Photonic Sciences in Barcelona and the Swiss Federal Institute of Technology in Zürich succeeded in accurately predicting the likelihood of events transiently violating the second law of thermodynamics. They immediately put the mathematical fluctuation theorem they derived to the test using a tiny glass sphere with a diameter of less than 100 nm levitated in a trap of laser light. Their experimental set-up allowed the research team to capture the nano-sphere and hold it in place, and, furthermore, to measure its position in all three spatial directions with exquisite precision. In the trap, the nano-sphere rattles around due to collisions with surrounding gas molecules. By a clever manipulation of the laser trap the scientists cooled the nano-sphere below the temperature of the surrounding gas and, thereby, put it into a non-equilibrium state. They then turned off the cooling and watched the particle relaxing to the higher temperature through energy transfer from the gas molecules. The researchers observed that the tiny glass sphere sometimes, although rarely, does not behave as one would expect according to the second law: the nano-sphere effectively releases heat to the hotter surroundings rather than absorbing the heat. The theory derived by the researchers to analyze the experiment confirms the emerging picture on the limitations of the second law on the nanoscale.

Given the theoretical descriptions of the applications mentioned in the news release, it sounds like at least one of them might be a ‘quantum computing project’,

The experimental and theoretical framework presented by the international research team in the renowned scientific journal Nature Nanotechnology has a wide range of applications. Objects with sizes in the nanometer range, such as the molecular building blocks of living cells or nanotechnological devices, are continuously exposed to a random buffeting due to the thermal motion of the molecules around them. As miniaturization proceeds to smaller and smaller scales nanomachines will experience increasingly random conditions. Further studies will be carried out to illuminate the fundamental physics of nanoscale systems out of equilibrium. The planned research will be fundamental to help us understand how nanomachines perform under these fluctuating conditions.

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

Dynamic Relaxation of a Levitated Nanoparticle from a Non-Equilibrium Steady State by Jan Gieseler, Romain Quidant, Christoph Dellago, and Lukas Novotny. Nature Nanotechnology AOP, February 28, 2014. DOI: 10.1038/NNANO.2014.40

The paper is behind a paywall but a free preview is available via ReadCube access.

INFERNOS: realizing Maxwell’s Demon

Before getting to the INFERNOS project and its relationship to Maxwell’s demon, I want to share a pretty good example of this ‘demon’ thought experiment which, as recently as Feb. 4, 2013, I featured in a piece about quantum dots,

James Clerk Maxwell, physicist,  has entered the history books for any number reasons but my personal favourite is Maxwell’s demon, a thought experiment he proposed in the 1800s to violate the 2nd law of thermodynamics. Lisa Zyga in her Feb. 1, 2013 article for phys.org provides an explanation,

When you open your door on a cold winter day, the warm air from your home and the cold air from outside begin to mix and evolve toward thermal equilibrium, a state of complete entropy where the temperatures outside and inside are the same. This situation is a rough example of the second law of thermodynamics, which says that entropy in a closed system never decreases. If you could control the air flow in a way that uses a sufficiently small amount of energy, so that the entropy of the system actually decreases overall, you would have a hypothetical mechanism called Maxwell’s demon.

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.

The Universitat de Barcelona (University of Barcelona) Oct. 7, 2013 news release, which originated the news item, provides more details about the project,

Although Maxwell’s Demon is one of the cornerstones of theoretical statistical mechanisms, little has been done about its definite experimental realization. Marco Ribezzi, researcher from the Department of Fundamental Physics, explains that “the principal novelty of INFERNOS is to bring a robust and rigorous experimental base for this field of knowledge. We aim at creating a device that can use information to supply/extract energy to/from a system”. In this sense, the UB group, in which researcher Fèlix Ritort from the former department also participates, focuses their activity on understanding how information and temperature changes are used in individual molecules manipulation.

From the theory side, researchers will work in order to develop a theory of the fluctuation processes in small systems, which would then facilitate efficient algorithms for the Maxwell’s Demon operation.

INFERNOS is a three-year European project of the programme Future and Emerging Technologies (FET). Besides the University of Barcelona, INFERNOS partners are: Aalto University (Finland), project coordinator, Lund University (Sweden), the University of Oslo (Norway), Delf University of Technology (Netherlands), the National Center for Scientific Research (France) and the Research Foundation of State University of New York.

I like the INFERNOS logo, demon and all,

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

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

The INFERNOS project website can be found here.

And for anyone who finds that music is the best way to learn, here are Flanders & Swann* performing ‘First and Second Law’ from a 1964 show,

Enjoy!

* ‘Swan’ corrected to ‘Swann’ on April 1, 2014.

Maxwell’s demon and quantum dots

James Clerk Maxwell, physicist,  has entered the history books for any number reasons but my personal favourite is Maxwell’s demon, a thought experiment he proposed in the 1800s to violate the 2nd law of thermodynamics. Lisa Zyga in her Feb. 1, 2013 article for phys.org provides an explanation,

When you open your door on a cold winter day, the warm air from your home and the cold air from outside begin to mix and evolve toward thermal equilibrium, a state of complete entropy where the temperatures outside and inside are the same. This situation is a rough example of the second law of thermodynamics, which says that entropy in a closed system never decreases. If you could control the air flow in a way that uses a sufficiently small amount of energy, so that the entropy of the system actually decreases overall, you would have a hypothetical mechanism called Maxwell’s demon.

Here’s how Maxwell describes his thought experiment along with a further explanation, from the Maxwell’s demon essay on Wikipedia (Note: I have removed links),

… if we conceive of a being whose faculties are so sharpened that he can follow every molecule in its course, such a being, whose attributes are as essentially finite as our own, would be able to do what is impossible to us. For we have seen that molecules in a vessel full of air at uniform temperature are moving with velocities by no means uniform, though the mean velocity of any great number of them, arbitrarily selected, is almost exactly uniform. Now let us suppose that such a vessel is divided into two portions, A and B, by a division in which there is a small hole, and that a being, who can see the individual molecules, opens and closes this hole, so as to allow only the swifter molecules to pass from A to B, and only the slower molecules to pass from B to A. He will thus, without expenditure of work, raise the temperature of B and lower that of A, in contradiction to the second law of thermodynamics….

In other words, Maxwell imagines one container divided into two parts, A and B. Both parts are filled with the same gas at equal temperatures and placed next to each other. Observing the molecules on both sides, an imaginary demon guards a trapdoor between the two parts. When a faster-than-average molecule from A flies towards the trapdoor, the demon opens it, and the molecule will fly from A to B. Likewise, when a slower-than-average molecule from B flies towards the trapdoor, the demon will let it pass from B to A. The average speed of the molecules in B will have increased while in A they will have slowed down on average. Since average molecular speed corresponds to temperature, the temperature decreases in A and increases in B, contrary to the second law of thermodynamics.

Two scientists, according to a recent study published in Physical Review Letters, have proposed a way of creating Maxwell’s demon, from Zyga’s article,

In a new study, Philipp Strasberg at the Institute of Technology in Berlin, and coauthors have proposed that Maxwell’s demon can be physically implemented with two interacting quantum dots connected to thermal reservoirs, where one dot takes the role of the demon and the other that of the controlled system. The experiment doesn’t violate the second law of thermodynamics, but it provides a very simple, minimalist implementation of the demon.

Here’s the proposition,

In their proposed experiment, the scientists coupled one dot to two reservoirs, which acts as a single-electron transistor, and coupled the second dot to another reservoir. The physicists showed that the second dot can be tuned to detect the transistor’s state, which is either empty (0) or filled (1). In order to do this, the two dots must be perfectly correlated, so that when the first dot (transistor) gets filled up, the second dot (detector) gets emptied, and vice versa. When the detector performs an infinitely fast and precise feedback, then the system receives additional information during entropy production.

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

Thermodynamics of a Physical Model Implementing a Maxwell Demon by Philipp Strasberg, Gernot Schaller, Tobias Brandes, and Massimiliano Esposito. Phys. Rev. Lett. 110, 040601 (2013) [5 pages] DOI: 10.1103/PhysRevLett.110.040601

This paper is behind a paywall.