Nowadays, they are not only intriguing oddities of nature, but also constitute crucial building blocks of modern technology: Ranging from data storage over medical instrumentation to transportation. And yet, to this day, they continue to puzzle scientists.
A novel experiment at the University of Hamburg utilizes matter waves to understand magnets. Magnets are built of elementary magnets which can point North (red) and South (blue), as can be seen in this computer simulation.
Credit: Center for Optical Quantum Technologies (ZOQ)
A novel approach to understand magnets was taken by a team of scientists lead by Klaus Sengstock and Ludwig Mathey from the Institute of Laser Physics at the University of Hamburg, with collaborators from Dresden, Innsbruck and Barcelona. In a joint experimental and theoretical effort, which was featured as the cover story of Nature Physics in November 2013, quantum matter waves made of Rubidium atoms were controlled in such a way that they mimic magnets. Under these well-defined conditions, these artificially created magnets can be studied with clarity, and can give a fresh perspective on long-standing riddles.
Quantum matter waves themselves are an intriguing state of atomic Rubidium clouds, based on a quantum mechanical effect predicted by Einstein and Bose as early as 1924 and observed for the first time in a ground-breaking experiment in 1995, which was later awarded with the Nobel prize.
Building on that experiment and developing it further, the team of scientists used infrared laser beams to force the atoms into a motion along triangular pathways, creating quantum matter waves that act as if they were magnets, like the ones you stick on your fridge. Speaking of cold, these atoms are about a trillion times colder than outer space.
"The experimental challenges are extraordinary", says lead experimental author Julian Struck. "For the atoms to move along the right trajectories, it is absolutely crucial that the laser beams are precisely stabilized. Otherwise, the motion of the atoms would be completely chaotic."
When a matter wave moves clockwise around a given triangle, as depicted in the illustration, the neighboring triangles are surrounded by counterclockwise motion. The resulting orientation at each triangle corresponds to a magnet pointing in North or South direction. These elementary magnets form domains and are in competition with each other, depicted in red and blue.
Lead theoretical author Robert Höppner explains: "We had to use a supercomputing facility such as the one at Juelich for our computer simulations of the experiment. Otherwise the complexity of the problem cannot be tackled. This allowed us to visualize the triangular magnets created by the condensate of atoms, and we learned about the subtle domain structure and how they respond in a magnetic field."
The results of this study have been published in the November issue of Nature Physics, where an illustration of the magnetic phases from the computer simulation is featured on the cover.
This research was supported by the Deutsche Forschungsgemeinschaft (GRK1355,SFB925), the Hamburg Center for Ultrafast Imaging (CUI) and the Landesexzellenzinitiative Hamburg (supported by the Joachim Herz Stiftung), ERC AdG QUAGATUA, AAII-Hubbard, Spanish MICINN (FIS2008-00784), Catalunya-Caixa, EU Projects AQUTE and NAMEQUAM, the Spanish foundation Universidad.es, the Austrian Science Fund (SFB F40 FOQUS), the DARPA OLE program and the John von Neumann Institute for Computing (NIC).
J.Struck, M.Weinberg, C.Ölschläger, P.Windpassinger, J.Simonet, K.Sengstock, R.Höppner, P.Hauke, A.Eckardt, M.Lewenstein & L.Mathey, "Engineering Ising-XY spin-models in a triangular lattice using tunable artificial gauge fields." Nature Physics (2013)
Robert Höppner | EurekAlert!
Physics boosts artificial intelligence methods
19.10.2017 | California Institute of Technology
NASA team finds noxious ice cloud on saturn's moon titan
19.10.2017 | NASA/Goddard Space Flight Center
University of Maryland researchers contribute to historic detection of gravitational waves and light created by event
On August 17, 2017, at 12:41:04 UTC, scientists made the first direct observation of a merger between two neutron stars--the dense, collapsed cores that remain...
Seven new papers describe the first-ever detection of light from a gravitational wave source. The event, caused by two neutron stars colliding and merging together, was dubbed GW170817 because it sent ripples through space-time that reached Earth on 2017 August 17. Around the world, hundreds of excited astronomers mobilized quickly and were able to observe the event using numerous telescopes, providing a wealth of new data.
Previous detections of gravitational waves have all involved the merger of two black holes, a feat that won the 2017 Nobel Prize in Physics earlier this month....
Material defects in end products can quickly result in failures in many areas of industry, and have a massive impact on the safe use of their products. This is why, in the field of quality assurance, intelligent, nondestructive sensor systems play a key role. They allow testing components and parts in a rapid and cost-efficient manner without destroying the actual product or changing its surface. Experts from the Fraunhofer IZFP in Saarbrücken will be presenting two exhibits at the Blechexpo in Stuttgart from 7–10 November 2017 that allow fast, reliable, and automated characterization of materials and detection of defects (Hall 5, Booth 5306).
When quality testing uses time-consuming destructive test methods, it can result in enormous costs due to damaging or destroying the products. And given that...
Using a new cooling technique MPQ scientists succeed at observing collisions in a dense beam of cold and slow dipolar molecules.
How do chemical reactions proceed at extremely low temperatures? The answer requires the investigation of molecular samples that are cold, dense, and slow at...
Scientists from the Max Planck Institute of Quantum Optics, using high precision laser spectroscopy of atomic hydrogen, confirm the surprisingly small value of the proton radius determined from muonic hydrogen.
It was one of the breakthroughs of the year 2010: Laser spectroscopy of muonic hydrogen resulted in a value for the proton charge radius that was significantly...
17.10.2017 | Event News
10.10.2017 | Event News
10.10.2017 | Event News
19.10.2017 | Materials Sciences
19.10.2017 | Materials Sciences
19.10.2017 | Physics and Astronomy