# Research News

## Surprises in the statistics of electronic states of quasi-periodic systems

Quasi-crystals are often alloys of 2-3 metals with a non-periodic arrangement of atoms. Still, they show the highly-peaked diffraction pattern of crystals while also possessing exotic electronic properties such as self-similar electronic spectra and multifractal wave functions usually associated with disordered materials. The level-spacing statistics of energy levels, P(s), with s the difference of adjacent energy levels, is known to be a marker that can distinguish ordered/periodic/metallic from disordered/non-periodic/insulating materials with ordered materials following a so-called Gaussian ensemble statistics. In a recent paper, Grimm and Roemer have shown that the Gaussian ensemble statistics also holds for quasi-periodic systems. Hence quasi-periodic systems seem to defy the usual classification where only ordered/periodic/metallic should show such a Gaussian statistics.

## Upper limit on electron scattering observed

The so-called *Planckian limit* on scattering of charge carriers is experimentally confirmed in a high-temperature superconductor.

## How growing cells process physical information

Cells grow and move. In cancer, the growth of one cell type over another is a key hallmark of the disease. But how do cells actually process information on local physical stresses, like pressure?

## A roadmap for ultrafast spectroscopy

Researchers from the Department have led and contributed to the 2021 Roadmap for Ultrafast Spectroscopy, highlighting trends and opportunities in the science of probing electron and atom motion on the shortest timescales feasible.

## PhD Thesis Prize 2021

Many congratulations to Drs **Elena Cukanovaite**, **James Gott** and **Samuele Ferracin**, for their success in the 2021 PhD Thesis Prize competition. Elena won the Winton Prize for Astrophysics, James was awarded the Springer Thesis Prize, while Samuele is the recipient of the Faculty of Science and Department of Physics Thesis prize. Read on for more details about the prizes and their research.

## Model Independent Simulation Complexity of Complex Systems

What happens at the molecular lever when a photon hits the eye or light shines on a leaf?

Physical processes occurring on nanometre length scales and femtosecond time scales typically undergo complex dynamics involving multilevel quantum systems. Understanding such complex quantum dynamics is a major open challenge. Foremost among them is the dimension of the Hilbert space** ** involved, which determines the number of parameters necessary for understanding the dynamics. This is typically done by fitting models of various degrees of sophistication to experimental data.