Solve complex physics problems at lightning speed

A calculation so complex that it takes 20 years to complete on a powerful desktop PC can now be done in an hour on a regular laptop. Physicist Andreas Ekström from Chalmers University of Technology, together with international research colleagues, has devised a new method to calculate the properties of atomic nuclei incredibly quickly.

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’s reminiscent of machine learning algorithms, but the researchers finally devised a completely new method. It opens up even more possibilities for basic research in fields such as nuclear physics.

“Now that we can emulate atomic nuclei using this method, we have a whole new tool to build and analyze theoretical descriptions of the forces between protons and neutrons inside the atomic nucleus,” says Research Director Andreas Ekström, Associate Professor in the Department of Physics. in Chalmers.

Fundamental to understanding our existence

The subject may seem like a niche, but it is in fact fundamental to understanding our existence and the stability and origin of visible matter. Most of the atomic mass resides in the center of the atom, in a dense region called the atomic nucleus. The particles that make up the nucleus, protons and neutrons, are held together by what is called the strong force. Although this force is so central to our existence, no one knows exactly how it works. To deepen our knowledge and unravel the fundamental properties of visible matter, researchers must be able to model the properties of atomic nuclei with great precision.

The basic research Andreas Ekström and his colleagues are working on sheds new light on topics ranging from neutron stars and their properties, to the deepest structure and the decay of nuclei. Basic research in nuclear physics also provides essential contributions to astrophysics, atomic physics and particle physics.

Opening doors to whole new possibilities

“I am extremely happy to be able to perform calculations with such precision and efficiency. Compared to our previous methods, I feel like we are now calculating at lightning speed. As part of our ongoing work here at Chalmers , we hope to further improve the emulation method., and perform advanced statistical analyzes of our quantum mechanical models. With this emulation method, it seems that we can get results that were previously considered impossible. This certainly opens the door to completely new possibilities, ”says Andreas Ekström.

Learn more about the math shortcut

The new method of emulation is based on something called eigenvector continuation (EVC). It enables the emulation of many quantum mechanical properties of atomic nuclei with incredible speed and precision. Instead of directly solving the complex and time-consuming multi-body problem, the researchers created a mathematical shortcut, using a transformation into a special subspace. This allows you to use a few exact solutions and then get rough solutions much faster.

If the emulator works fine, it generates solutions that are almost exactly – around 99% – similar to the solutions of the original problem. These are in many ways the same principles used in machine learning, but it is not a neural network or a Gaussian process – a completely new method underpins it. The EVC emulation method is not limited to atomic nuclei, and researchers are currently studying different types of applications in more detail.