Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

When Nanotechnology Meets Quantum Physics in One Dimension

24.01.2014
New experiment supports long-predicted “Luttinger liquid” model

How would electrons behave if confined to a wire so slender they could pass through it only in single-file?

The question has intrigued scientists for more than half a century. In 1950, Japanese Nobel Prize winner Sin-Itiro Tomonaga, followed by American physicist Joaquin Mazdak Luttinger in 1963, came up with a mathematical model showing that the effects of one particle on all others in a one-dimensional line would be much greater than in two- or three-dimensional spaces. Among quantum physicists, this model came to be known as the “Luttinger liquid” state.

Until very recently, however, there had been only a few successful attempts to test the model in devices similar to those in computers, because of the engineering complexity involved. Now, scientists from McGill University and Sandia National Laboratories have succeeded in conducting a new experiment that supports the existence of the long-sought-after Luttinger liquid state. Their findings, published in the Jan. 23 issue of Science Express, validate important predictions of the Luttinger liquid model.

The experiment was led by McGill PhD student Dominique Laroche under the supervision of Professor Guillaume Gervais of McGill’s Department of Physics and Dr. Michael Lilly of Sandia National Laboratories in Albuquerque, N.M. The new study follows on the team’s discovery in 2011 of a way to engineer one of the world’s smallest electronic circuits, formed by two wires separated by only about 15 nanometers, or roughly 150 atoms.

What does one-dimensional quantum physics involve? Gervais explains it this way: “Imagine that you are driving on a highway and the traffic is not too dense. If a car stops in front of you, you can get around it by passing to the left or right. That’s two-dimensional physics. But if you enter a tunnel with a single lane and a car stops, all the other cars behind it must slam on the brakes. That’s the essence of the Luttinger liquid effect. The way electrons behave in the Luttinger state is entirely different because they all become coupled to one another.”

To scientists, “what is so fascinating and elegant about quantum physics in one dimension is that the solutions are mathematically exact,” Gervais adds. “In most other cases, the solutions are only approximate.”

Making a device with the correct parameters to conduct the experiment was no simple task, however, despite the team’s 2011 discovery of a way to do so. It took years of trial, and more than 250 faulty devices – each of which required 29 processing steps – before Laroche’s painstaking efforts succeeded in producing functional devices yielding reliable data. “So many things could go wrong during the fabrication process that troubleshooting the failed devices felt like educated guesswork at times,” explains Laroche. “Adding in the inherent failure rate compounded at each processing step made the fabrication of these devices extremely challenging.”

In particular, the experiment measures the effect that a very small electrical current in one of the wires has on a nearby wire. This can be viewed as the “friction” between the two circuits, and the experiment shows that this friction increases as the circuits are cooled to extremely low temperatures. This effect is a strong prediction of Luttinger liquid theory.

The experiments were conducted both at McGill University and at the Center for Integrated Nanotechnologies, a U.S. Department of Energy, Office of Basic Energy Sciences user facility operated by Sandia National Laboratories.

"It took a very long time to make these devices," said Lilly. "It's not impossible to do in other labs, but Sandia has crystal-growing capabilities, a microfabrication facility, and support for fundamental research from DOE's office of Basic Energy Sciences (BES), and we're very interested in understanding the fundamental ideas that drive the behavior of very small systems."

The findings could lead to practical applications in electronics and other fields. While it’s difficult at this stage to predict what those might be, “the same was true in the case of the laser when it was invented,” Gervais notes. “Nanotechnologies are already helping us in medicine, electronics and engineering – and this work shows that they can help us get to the bottom of a long-standing question in quantum physics.”

The research was supported by the Division of Materials Sciences and Engineering, Office of Basic Energy Sciences, U.S. Department of Energy; the Natural Sciences and Engineering Research Council of Canada (NSERC); the Canadian Institute for Advanced Research (CIFAR), and the Fonds québécois de la recherche sur la nature et les technologies (FQRNT).

Chris Chipello | Newswise
Further information:
http://www.mcgill.ca

More articles from Physics and Astronomy:

nachricht Spiral arms: not just in galaxies
30.09.2016 | Max-Planck-Institut für Radioastronomie

nachricht Discovery of an Extragalactic Hot Molecular Core
29.09.2016 | National Astronomical Observatory of Japan

All articles from Physics and Astronomy >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: First-Ever 3D Printed Excavator Project Advances Large-Scale Additive Manufacturing R&D

Heavy construction machinery is the focus of Oak Ridge National Laboratory’s latest advance in additive manufacturing research. With industry partners and university students, ORNL researchers are designing and producing the world’s first 3D printed excavator, a prototype that will leverage large-scale AM technologies and explore the feasibility of printing with metal alloys.

Increasing the size and speed of metal-based 3D printing techniques, using low-cost alloys like steel and aluminum, could create new industrial applications...

Im Focus: New welding process joins dissimilar sheets better

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of light metals.
Scientists at the University of Stuttgart have now developed two new process variants that will considerably expand the areas of application for friction stir welding.
Technologie-Lizenz-Büro (TLB) GmbH supports the University of Stuttgart in patenting and marketing its innovations.

Friction stir welding is a still-young and thus often unfamiliar pressure welding process for joining flat components and semi-finished components made of...

Im Focus: First quantum photonic circuit with electrically driven light source

Optical quantum computers can revolutionize computer technology. A team of researchers led by scientists from Münster University and KIT now succeeded in putting a quantum optical experimental set-up onto a chip. In doing so, they have met one of the requirements for making it possible to use photonic circuits for optical quantum computers.

Optical quantum computers are what people are pinning their hopes on for tomorrow’s computer technology – whether for tap-proof data encryption, ultrafast...

Im Focus: OLED microdisplays in data glasses for improved human-machine interaction

The Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP has been developing various applications for OLED microdisplays based on organic semiconductors. By integrating the capabilities of an image sensor directly into the microdisplay, eye movements can be recorded by the smart glasses and utilized for guidance and control functions, as one example. The new design will be debuted at Augmented World Expo Europe (AWE) in Berlin at Booth B25, October 18th – 19th.

“Augmented-reality” and “wearables” have become terms we encounter almost daily. Both can make daily life a little simpler and provide valuable assistance for...

Im Focus: Artificial Intelligence Helps in the Discovery of New Materials

With the help of artificial intelligence, chemists from the University of Basel in Switzerland have computed the characteristics of about two million crystals made up of four chemical elements. The researchers were able to identify 90 previously unknown thermodynamically stable crystals that can be regarded as new materials. They report on their findings in the scientific journal Physical Review Letters.

Elpasolite is a glassy, transparent, shiny and soft mineral with a cubic crystal structure. First discovered in El Paso County (Colorado, USA), it can also be...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

Call for Paper – Panacea Green Infrastructure?

30.09.2016 | Event News

HLF: From an experiment to an establishment

29.09.2016 | Event News

European Health Forum Gastein 2016 kicks off today

28.09.2016 | Event News

 
Latest News

First-Ever 3D Printed Excavator Project Advances Large-Scale Additive Manufacturing R&D

30.09.2016 | Materials Sciences

New Technique for Finding Weakness in Earth’s Crust

30.09.2016 | Earth Sciences

Cells migrate collectively by intermittent bursts of activity

30.09.2016 | Life Sciences

VideoLinks
B2B-VideoLinks
More VideoLinks >>>