Using some of the largest supercomputers available, physics researchers from the University of Illinois at Urbana-Champaign have produced one of the largest simulations ever to help explain one of physics most daunting problems.
"This result was a fantastic collaboration between theory and experiment," explained Physics Professor Brian DeMarco, whose group led the experimental phase of the study.
Figure illustrates puddles of localized quasi-condensates found using a quantum Monte Carlo simulation of trapped atoms in a disordered lattice. Individual puddles, consisting of 10-20 particles each, are incoherent relative to each other. The Bose glass is composed of these puddle-like structures.
Credit: Ushnish Ray, University of Illinois
"One of the grandest and most impactful frontiers of physics is the quantum many-particle problem. We do not understand very well what happens when many quantum particles come together and interact with each other. This problem spans some of the largest scales in the universe, like understanding the nuclear matter in neutron stars, to the smallest, such as electron transport in photosynthesis and the quarks and gluons inside a proton."
DeMarco's group experiments with atoms gases cooled to just billionths of a degree above absolute zero temperature in order to experimentally simulate models of materials such as high-temperature superconductors. In these experiments, the atoms play the role of electrons in a material, and the analog of material parameters (like disorder) are completely controlled and known and can be changed every 90-second experimental cycle. Measurements on the atoms are used to expose new physics and test theories.
"In most cases, we lack predictive power, because these problems are not readily computable -- a classical computer requires exponentially costly resources to simulate many quantum systems," added David Ceperley, a professor of physics whose team developed the companion simulation. "A key example of this problem with practical challenges lies with materials such as high-temperature superconductors. Even armed with the chemical composition and structure of these materials, it is almost impossible to predict today at what temperature they will super-conduct."
The different approaches to attacking a particularly important quantum many-particle problem by DeMarco's and Ceperley's groups came together in a new result published in Nature Physics. In their paper, "Probing the Bose glass-superfluid transition using quantum quenches of disorder," Carolyn Meldgin from DeMarco's group and Ushnish Ray from Ceperley's team share a new understanding of how disorder in a quantum material gives rise to an exotic quantum state called a Bose glass.
"A Bose glass is a strange and poorly understood insulator that can occur when disorder is added to a superfluid or superconductor," Meldgin said. In her experiments, Meldgin was able to use optical disorder to induce a Bose glass, and Ray exactly simulated the experiment using the Titan supercomputer.
In this work, Ceperley's group achieved the largest scale computer simulations possible of a disordered quantum many-particle system on the biggest supercomputers in existence. These computer simulations were able to simulate relatively large numbers of particles, such as the 30,000 atoms used in DeMarco's experiments.
Together, Meldgin and Ray were able to show something startling--that a dynamic probe in the experiment connects to the equilibrium computer simulations.
"In both cases, the same amount of disorder is required to turn a superfluid into a Bose-glass," Ray stated. "This result is critically important to our understanding of disordered quantum materials, which are ubiquitous, since disorder is difficult to avoid. It also has important implications for quantum annealers, like the D-Wave Systems device."
Brian DeMarco | EurekAlert!
New design improves performance of flexible wearable electronics
23.06.2017 | North Carolina State University
Plant inspiration could lead to flexible electronics
22.06.2017 | American Chemical Society
An international team of scientists has proposed a new multi-disciplinary approach in which an array of new technologies will allow us to map biodiversity and the risks that wildlife is facing at the scale of whole landscapes. The findings are published in Nature Ecology and Evolution. This international research is led by the Kunming Institute of Zoology from China, University of East Anglia, University of Leicester and the Leibniz Institute for Zoo and Wildlife Research.
Using a combination of satellite and ground data, the team proposes that it is now possible to map biodiversity with an accuracy that has not been previously...
Heatwaves in the Arctic, longer periods of vegetation in Europe, severe floods in West Africa – starting in 2021, scientists want to explore the emissions of the greenhouse gas methane with the German-French satellite MERLIN. This is made possible by a new robust laser system of the Fraunhofer Institute for Laser Technology ILT in Aachen, which achieves unprecedented measurement accuracy.
Methane is primarily the result of the decomposition of organic matter. The gas has a 25 times greater warming potential than carbon dioxide, but is not as...
Hydrogen is regarded as the energy source of the future: It is produced with solar power and can be used to generate heat and electricity in fuel cells. Empa researchers have now succeeded in decoding the movement of hydrogen ions in crystals – a key step towards more efficient energy conversion in the hydrogen industry of tomorrow.
As charge carriers, electrons and ions play the leading role in electrochemical energy storage devices and converters such as batteries and fuel cells. Proton...
Scientists from the Excellence Cluster Universe at the Ludwig-Maximilians-Universität Munich have establised "Cosmowebportal", a unique data centre for cosmological simulations located at the Leibniz Supercomputing Centre (LRZ) of the Bavarian Academy of Sciences. The complete results of a series of large hydrodynamical cosmological simulations are available, with data volumes typically exceeding several hundred terabytes. Scientists worldwide can interactively explore these complex simulations via a web interface and directly access the results.
With current telescopes, scientists can observe our Universe’s galaxies and galaxy clusters and their distribution along an invisible cosmic web. From the...
Temperature measurements possible even on the smallest scale / Molecular ruby for use in material sciences, biology, and medicine
Chemists at Johannes Gutenberg University Mainz (JGU) in cooperation with researchers of the German Federal Institute for Materials Research and Testing (BAM)...
19.06.2017 | Event News
13.06.2017 | Event News
13.06.2017 | Event News
23.06.2017 | Physics and Astronomy
23.06.2017 | Physics and Astronomy
23.06.2017 | Information Technology