Five New Professors at the Department of Physics and Astronomy

The physics of atoms, molecules and materials connects the smallest scales of time and space with the largest, and finds applications in the technology around us. My research concerns charge and material transport across surfaces and boundary layers in materials – fundamental processes that, in applications, increase or destroy the efficiency and lifespan of batteries, solar cells and electronics. The natural scales for these transport processes are nanometres, i.e. one billionth of a metre, approximately ten atoms, and attoseconds (one billionth of a billionth of a second, a light pulse travelling along an atom) to hours. I use electron spectroscopy, which determines the energy of electrons from atoms, alone or in molecules and materials, ionised by X-rays. The X-rays are produced on a laboratory scale or at larger facilities such as electron storage rings for synchrotron light, for example MAX IV in Lund, or free-electron lasers, such as at X-FEL in Hamburg. Larger facilities provide access to a higher quality of X-ray light, which allows for experiments with a higher level of ambition and scope.

By measuring the variation in secondary processes after the supply of X-ray energy, my research group and I have been able to show that an electron jumps from an atom to a surface in around a hundred attoseconds. This time is extremely sensitive to the local energy landscape and can be used to study, for example, how a boundary layer in a solar cell changes over time.

For an astronomer, the night sky acts as a time machine. Due to the vast distances in space, it can take a very long time for light from distant light sources to reach us – we therefore do not see them in their current state, but as they looked long ago. We can see the closest stars as they were just a few years or decades ago, but for the most distant astronomical objects known today, the light has travelled for more than thirteen billion years to reach us. At such distances, we see star clusters, galaxies and black holes that existed when the universe was only a few per cent of its current age.

In my research, I use these extremely distant light sources to understand what happened in the early universe – in the era when the first stars, galaxies and black holes were formed. To capture enough light from these distant celestial objects, we use various giant telescopes, both on the Earth’s surface and in space, to make our measurements.

In addition to researching the early epochs of the universe, I am also interested in the question of whether life exists elsewhere than on Earth, and I am leading a project that searches for other civilisations in our home galaxy, the Milky Way.

In my research, I investigate how electrons in an electron microscope interact with solid materials. As a theorist, I focus on developing new theories and effective methods for simulating how electrons scatter, especially in magnetic materials and during atomic vibrations.

This research contributes to a deeper understanding of innovative experiments performed with electron microscopes, enabling us to reveal the properties of materials with very high spatial resolution – down to individual columns of atoms. This information is invaluable in today’s nanotechnology, which often exploits unusual properties at the interface between two materials or in nanoparticles.

The methods I am developing have applications in several areas, such as heat management in the design of new integrated circuits, magnetic storage devices, or future information technologies under development, such as spintronics, magnonics, and orbitronics.

“Seeing is believing,” as the old saying goes. Every year, around 50,000 researchers worldwide, including several hundred in Sweden, use X-ray photon beams at synchrotron and X-ray free electron laser (XFEL) facilities to explore the structure and dynamics of matter. Thanks to the development of synchrotron light sources, techniques such as protein crystallography and X-ray-driven catalysis in biomolecules have become important tools in modern science.

The advent of XFELs has opened the door to biological imaging with femtosecond X-ray pulses (one trillionth of a billionth of a second), which has revolutionised structural biology by enabling the study of molecules in motion. Technological advances in synchrotrons and FELs have changed how we investigate the microcosm – from atoms and molecules to quasiparticles in advanced materials.

My research focuses on the development of accelerator-based sources of X-ray photon beams with extreme brightness and ultra-short pulse lengths down to the attosecond regime, i.e. one billionth of a billionth of a second. The attosecond is the natural unit of time in the world of atoms and molecules. We can understand how short an attosecond is with the following analogy: there are as many seconds in the history of the universe as there are attoseconds in a second.

Our world follows two very different types of physical laws. The small, light building blocks of matter obey the random rules of quantum mechanics. The large-scale structure of the universe is determined by Einstein’s theory of relativity, which describes how space-time curves around large, heavy objects. My research concerns string theory, which describes the laws of physics when both quantum mechanical and relativistic effects are important – which is the case in the very young universe, or the interior of a black hole – and which reduces to Einstein’s theory of relativity at low energies.

String theory provides models for interesting physics, but with these come new spatial dimensions. I am investigating what these extra dimensions might look like and how their shape determines four-dimensional physics. What geometries describe the physics we observe in the microcosm and macrocosm? Conversely, can string physics be used to increase our understanding of geometry and related fields in mathematics? Together with my colleagues, I am developing methods in physics, mathematics and computer science to answer these questions.