Tag Archives: Romain Quidant

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.

Nanodiamonds and a broken heart

Nanowerk’s March 3, 2013 news item highlights some research with biomedical applications taking place in Australia,

Researchers at Macquarie University have been perfecting a technique that may help see nanodiamonds used in biomedical applications. PhD student Jana Say has been working on processing the raw diamonds so that they might be used as a tag for biological molecules.

“We are working with nanodiamonds to process them so that they are stable enough to be used as a probe for single-molecule interactions. As diamonds are made from carbon, they are non-toxic which makes them advantageous for many biological applications over other nanoparticles,” says Say.

The Macquarie University Feb. 13, 2013 news release, which originated the Nanowerk news item, provides more detail,

The processing technique has already contributed to the success of research projects that have used the diamonds. Working with an international team, Say’s diamonds were able to be optically trapped and manipulated in three-dimensions – this first time this has been achieved.

The diamonds themselves are incredibly small, 5000 times smaller than a human hair, and so the real strength in Say’s technique is her ability to consistently produce stable samples.

“The real challenge is reliably producing the same sample. It’s a very repetitive and involved process to prepare and characterise these diamonds,” she says.

Say, under the supervision of Dr Louise Brown of the Department of Chemistry and Biomolecular Sciecnes, has plans to continue to develop these diamonds and collaborate with other researchers to explore their full potential.

“Jana’s work is incredibly important,” says Dr Brown. “These diamonds were recently used in a project which won a Macquarie University research excellence award for demonstrating that nanodiamonds can be isolated and made to emit light. With this work, we continue to make real breakthroughs in this area and are contributing to the long term goals in ultrasensitive imaging and sensing technologies.”

For anyone who’s interested, here’s a citation and link to the research paper,

Three-dimensional optical manipulation of a single electron spin by Michael Geiselmann, Mathieu L. Juan, Jan Renger, Jana M. Say, Louise J. Brown,  F. Javier García de Abajo, Frank Koppens & Romain Quidant. Nature Nanotechnology (2013) doi:10.1038/nnano.2012.259 Published online 10 February 2013

The article is behind a paywall. One final comment, I very much enjoyed the fanciful title for the news release about this work, Diamonds may mend a broken heart: Researchers perfect nanodiamonds for use in biomedical applications.