New discoveries in quantum materials

BY MICHAEL ZUERCH ILLUSTRATIONS: ELLA MARU STUDIO

Understanding the underlying phenomena is critical for the design of future quantum materials and their integration into complex devices. Traditionally, researchers have focused on modifying these materials’ properties using static methods such as strain, temperature, applied electric and magnetic fields, chemical composition, or advanced geometric assembly. Now researchers are starting to study time-dependent properties in quantum materials by using light pulses to dynamically engineer material properties with response times down to the femtosecond timescale often referred to as “ultrafast timescale”. Such dynamical control is particularly important in applications that require fast switching of a material property such as in memory and computation.

Largely unexplored are such questions as, how tiny energy fluctuations in a system with coupled degrees of freedom can lead to drastic changes of macroscopic properties; how exotic ground or excited states emerge from changes in crystal symmetry or electronic topology; and how quantum materials behave in realistic environments for integration into real-world applications. An example of this is a mysterious phase of matter called strangemetal phase, which exhibits transport phenomena without well-defined quasiparticles. While we know this phase exists and has been observed in many quantum materials, it does not follow known concepts of transport and even a theoretical description is absent. Sparked by curiosity to understand the underlaying physical phenomena, scientists are currently working to describe and measure this phase from a spectroscopic or symmetry point of view.

Ultrafast techniques such as photoemission, scattering, and optical spectroscopies have become powerful tools for studying timedependent properties in quantum materials. However, conventional time-resolved methods