Physicists have developed a new method that can quickly follow complex calculations. It can provide new insights into the quantum properties of strong interaction between matter such as atomic nuclei and neutron stars. Illustration: Andreas Ekström and Yen Strandqvist / Chalmers University of Technology. Credit: Andreas Ekström and Yen Strandqvist / Chalmers University of Technology
A calculation that is so complicated that it takes twenty years to complete on a powerful desktop computer can now be done in one hour on a regular laptop. Physicist Andreas Ekström at research intensive University of Gothenburg, Sweden, which was founded in 1829 after a donation by William Chalmers, a director of the Swedish East India Company. It focuses on technology, science, architecture and shipping. “Class =” glossaryLink “> Chalmers University of Technologytogether with international research partners, designed a new method to calculate the properties of atomic nuclei incredibly fast.
The new approach is based on a concept called emulation, where an approximate calculation replaces a complete and more complex calculation. Although the researchers take a shortcut, the solution ends up almost exactly the same. It is reminiscent of machine learning algorithms, but eventually the researchers devised a completely new method. It offers even more possibilities in fundamental research in areas such as nuclear physics.
“Now that we can trace atomic nuclei with this method, we have an entirely new tool to construct and analyze theoretical descriptions of the forces between protons and neutrons in the atomic nucleus,” says research leader Andreas Ekström, associate professor at the Department of Physics. by Chalmers.
Fundamental to understanding our existence
The subject may sound niche, but it is in fact fundamental to understand our existence and the stability and origin of visible matter. The largest atomic mass is in the middle of the atom, in a dense region called the atomic nucleus. The constituent particles of the nucleus, the protons and neutrons, are held together by something called the strong force. Although this power is so central to our existence, no one knows exactly how it works. To increase our knowledge and unravel the fundamental properties of visible matter, researchers need to explore the properties of atomic nuclei with large accuracy.
Andreas Ekström, Associate Professor, Department of Physics, Chalmers University of Technology Photo: Anna-Lena Lundqvist / Chalmers University of Technology. Credit: Anna-Lena Lundqvist / Chalmers University of Technology
The basic research that Andreas Ekström and his colleagues are working on sheds new light on topics ranging from neutron stars and their properties, to the inner structure and decay of nuclei. Basic research in nuclear physics also provides essential input to astrophysics, atomic physics and particle physics.
Open doors for completely new possibilities
‘I’m incredibly excited to be able to do calculations with so much accuracy and efficiency. Compared to our previous methods, it feels like we are now calculating at lightning speed. In our ongoing work here at Chalmers, we hope to further improve the emulsification method and perform advanced statistical analyzes of our quantum mechanical models. With this emulation method, it seems that we can achieve results that were previously considered impossible. It definitely opens doors for completely new possibilities, ”says Andreas Ekström.
More about the mathematical shortcut
The new emulation method is based on something called eigenvector continuation (EVC). It allows for the emulation of many quantum mechanical properties of atomic nuclei with incredible speed and accuracy. Instead of solving the time-consuming and complicated multiple problem directly, researchers have created a mathematical shortcut that uses a transformation into a special subspace. This makes it possible to use some precise solutions to then get much faster approximate solutions.
Plot the energy and radius of the oxygen isotope 16-O for 100,000 different parameterizations of the strong nuclear interaction. Using the new method, the results were generated within a few minutes on a standard laptop. The dotted lines indicate the values of experimental data. Illustration: Andreas Ekström and Yen Strandqvist / Chalmers University of Technology. Credit: Andreas Ekström and Yen Strandqvist / Chalmers University of Technology
If the emulator works well, it generates solutions that are almost exactly – about 99 percent – similar to the solutions to the original problem. These are in many ways the same principles used in machine learning, but they are not a neural network or a Gaussian process – a completely new method supports them. The EVC method of emulation is not limited to atomic nuclei, and researchers are currently investigating different types of applications.
References:
“Continuation of Eigenvector as an Efficient and Accurate Emulator for Quantifying Uncertainty” by S. König, A. Ekström, K. Hebeler, D. Lee and A. Schwenk, 30 September 2020, Physics Letters B.
DOI: 10.1016 / j.physletb.2020.135814
“Global Sensitivity Analysis of Bulk Properties of an Atomic Nucleus” by Andreas Ekström and Gaute Hagen, 20 December 2019, Physical overview letters.
DOI: 10.1103 / PhysRevLett.123.252501