Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Quantum Simulator Gives Clues About Magnetism

19.05.2014

Science paper reveals new clues about how ultracold atoms interact, including how they can switch from non-interacting to strongly interacting in only a millisecond.

Assembling the puzzles of quantum materials is, in some ways, like dipping a wire hanger into a vat of soapy water, says CIFAR (Canadian Institute for Advanced Research) Fellow Joseph Thywissen (University of Toronto).

Long before mathematical equations could explain the shapes and angles in the soap foams, mathematicians conjectured that soap films naturally found the geometry that minimized surface area, thus solving the problem of minimal surfaces. They could be created simply by blowing soap bubbles.

At the University of Toronto’s Ultracold Atoms Lab, Thywissen and his team strive to answer what he calls “soap bubble” questions — deep mysteries of the enigmatic quantum materials world that simulations can help us solve. Since the electrons within quantum materials, such as superconductors, zoom far too quickly for careful observation, Thywissen’s team uses ultracold gases instead, in this way simulating one quantum system with another, more easily studied, quantum system.

“Simulation gives you the answers but not the theory behind them,” says Thywissen.

Thywissen’s lab has revealed some of these answers in a new paper about the magnetism and diffusion of atoms in ultracold gases, published in the journal Science. The researchers optically trapped a cloud of gas a billion times colder than air in a very low-pressure vacuum.

They oriented the ultracold atoms, which behave like microscopic magnets, to make them all point in the same direction in space, then manipulated the spins with an effect that’s regularly used in hospitals for MRIs, called a spin echo.

Twisting up the direction into a corkscrew pattern and then untwisting it, they measured the strength of interactions between atoms. They observed that at first the atoms did not interact, but one millisecond later they were strongly interacting and correlated.

This rapid change suggested that something was happening to alter the atoms’ magnetism as the process unfolded.

“The Pauli Principle forbids identical ultracold atoms from interacting, so we knew something was scrambling the spins at a microscopic level,” Thywissen says.

What was happening, the researchers learned next, was diffusion — the same process that takes place when the smell of perfume fills the air of a room, for example.

“If I open a bottle of perfume in the front of the room, it takes a little while for those particles to diffuse to the back of the room,” Thywissen says. “They bump into other particles on the way, but eventually get there. You can imagine that the more particles bump into each other, the slower diffusion occurs.”

Cranking up interactions to their maximum allowed level, the Toronto team tried to see how slow diffusion could be. They lowered temperature below a millionth of a degree above absolute zero. You might guess that the speed of diffusion would eventually reach zero, but instead the experiment found a lower limit to diffusion.

“Whereas cars on the freeway need to drive below the speed limit, strongly interacting spins need to diffuse above a quantum speed limit,” Thywissen says.

Ultracold atoms are just one of a larger family of strongly interacting materials, that also include superconductors and magnetic materials. Thywissen is a member of the CIFAR Quantum Materials program, which is developing an understanding of these materials’ novel properties. Cold atoms offer a promising way to explore the mystery of how electrons self-organize to exhibit unusual and valuable properties, such as superconductivity. Quantum materials contain mysteries that have challenged physicists for decades.

"Our measurements imply a diffusivity bound whose mathematical simplicity is exciting: it hints at a universal principle about spin transport, waiting to be uncovered,” he says.

Thywissen says CIFAR’s support helped make this successful experiment possible.

“CIFAR enabled me to assemble a world-class team.”

***
The authors on the paper “Transverse Demagnetization Dynamics of a Unitary Fermi Gas,” published in Science, are Alma Bardon, Scott Beattie, Chris Luciuk, Will Cairncross, Daniel Fine, Nathan Cheng, Graham Edge, Edward Taylor, Shizhong Zhang, Stefan Trotzky and Joseph Thywissen.

About CIFAR

CIFAR brings together extraordinary scholars and scientists from around the world to address questions of global importance. Based in Toronto, Canada, CIFAR is a global research organization comprising nearly 400 fellows, scholars and advisors from more than 100 institutions in 16 countries. The Institute helps to resolve the world’s major challenges by contributing transformative knowledge, acting as a catalyst for change, and developing a new generation of research leaders. Established in 1982, CIFAR partners with the Government of Canada, provincial governments, individuals, foundations, corporations and research institutions to extend our impact in the world.

CIFAR’s program in Quantum Materials invents and explores materials whose novel and unusual electronic properties, like superconductivity, could revolutionize technology.

For more information including images, contact:

Lindsay Jolivet
Writer & Media Relations Specialist
Canadian Institute for Advanced Research
lindsay.jolivet@cifar.ca
416-971-4876

Joseph Thywissen
University of Toronto
jht@physics.utoronto.ca
416-978-2941 (Office)

Dominic Ali | newswise

Further reports about: CIFAR Magnetism Quantum Simulator Toronto diffuse electrons interactions materials microscopic superconductors

More articles from Physics and Astronomy:

nachricht NUS engineers develop novel method for resolving spin texture of topological surface states using transport measurements
26.04.2018 | National University of Singapore

nachricht European particle-accelerator community publishes the first industry compendium
26.04.2018 | Fraunhofer-Institut für Organische Elektronik, Elektronenstrahl- und Plasmatechnik FEP

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: Why we need erasable MRI scans

New technology could allow an MRI contrast agent to 'blink off,' helping doctors diagnose disease

Magnetic resonance imaging, or MRI, is a widely used medical tool for taking pictures of the insides of our body. One way to make MRI scans easier to read is...

Im Focus: BAM@Hannover Messe: innovative 3D printing method for space flight

At the Hannover Messe 2018, the Bundesanstalt für Materialforschung und-prüfung (BAM) will show how, in the future, astronauts could produce their own tools or spare parts in zero gravity using 3D printing. This will reduce, weight and transport costs for space missions. Visitors can experience the innovative additive manufacturing process live at the fair.

Powder-based additive manufacturing in zero gravity is the name of the project in which a component is produced by applying metallic powder layers and then...

Im Focus: Molecules Brilliantly Illuminated

Physicists at the Laboratory for Attosecond Physics, which is jointly run by Ludwig-Maximilians-Universität and the Max Planck Institute of Quantum Optics, have developed a high-power laser system that generates ultrashort pulses of light covering a large share of the mid-infrared spectrum. The researchers envisage a wide range of applications for the technology – in the early diagnosis of cancer, for instance.

Molecules are the building blocks of life. Like all other organisms, we are made of them. They control our biorhythm, and they can also reflect our state of...

Im Focus: Spider silk key to new bone-fixing composite

University of Connecticut researchers have created a biodegradable composite made of silk fibers that can be used to repair broken load-bearing bones without the complications sometimes presented by other materials.

Repairing major load-bearing bones such as those in the leg can be a long and uncomfortable process.

Im Focus: Writing and deleting magnets with lasers

Study published in the journal ACS Applied Materials & Interfaces is the outcome of an international effort that included teams from Dresden and Berlin in Germany, and the US.

Scientists at the Helmholtz-Zentrum Dresden-Rossendorf (HZDR) together with colleagues from the Helmholtz-Zentrum Berlin (HZB) and the University of Virginia...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

VideoLinks
Industry & Economy
Event News

Invitation to the upcoming "Current Topics in Bioinformatics: Big Data in Genomics and Medicine"

13.04.2018 | Event News

Unique scope of UV LED technologies and applications presented in Berlin: ICULTA-2018

12.04.2018 | Event News

IWOLIA: A conference bringing together German Industrie 4.0 and French Industrie du Futur

09.04.2018 | Event News

 
Latest News

World's smallest optical implantable biodevice

26.04.2018 | Power and Electrical Engineering

Molecular evolution: How the building blocks of life may form in space

26.04.2018 | Life Sciences

First Li-Fi-product with technology from Fraunhofer HHI launched in Japan

26.04.2018 | Power and Electrical Engineering

VideoLinks
Science & Research
Overview of more VideoLinks >>>