A team from the University of Geneva (UNIGE), in collaboration with the University of Salerno and the CNR-SPIN Institute (Italy), has made a significant breakthrough by discovering a previously unknown geometry that distorts electron trajectories in the same way that gravity bends the path of light. The study, which was published in Science, offers new possibilities for quantum electronics.
A glimpse into how hidden geometry shapes the motion of electrons in quantum materials. Electrons flowing upstream feel an extra resistance that reveals the quantum metric. Image Credit: Xavier Ravinet – UNIGE
How can data be processed at lightning speed and transmit electricity without energy loss? To achieve this, scientists and industry leaders are increasingly looking to quantum materials, which are governed by the strange rules of the quantum world. Designing these advanced materials requires a deep understanding of atomic-scale behavior, much of which remains a mystery.
Future technologies depend on high-performance materials with unique properties grounded in quantum physics. At the heart of this progress is the microscopic study of matter, the foundation of quantum science. Over the past century, exploring how atoms, electrons, and photons behave within materials has paved the way for innovations like the transistor, ultimately giving rise to modern computing.
New quantum phenomena that challenge existing theories continue to be found today. Recent research suggests that when large numbers of particles interact within certain materials, a kind of geometry can emerge. This geometry seems to influence the paths of electrons, much like how Einstein’s theory of gravity describes the bending of light by massive objects.
From Theory to Observation
This geometry, also known as quantum metric, depicts the curvature of the quantum space in which electrons flow. It plays an important part in many microscopic phenomena. However, recognizing its existence and effects remains a significant difficulty.
The concept of quantum metric dates back about 20 years, but for a long time it was regarded purely as a theoretical construct. Only in recent years have scientists begun to explore its tangible effects on the properties of matter.
Andrea Caviglia, Full Professor and Director, Department of Quantum Matter Physics, Faculty of Science, University of Geneva
Recently, a team led by the UNIGE researcher, in collaboration with Carmine Ortix, Associate Professor in the Department of Physics at the University of Salerno, discovered a quantum metric at the interface of two oxides — strontium titanate and lanthanum aluminate, a well-known quantum material.
Its presence can be revealed by observing how electron trajectories are distorted under the combined influence of quantum metric and intense magnetic fields applied to solids.
Giacomo Sala, Study Lead Author and Research Associate, Department of Quantum Matter Physics, Faculty of Science, University of Geneva
Unlocking Future Technologies
By observing this phenomenon, one can more precisely characterize the optical, electronic, and transport characteristics of a material. In addition, the study team shows that, in contrast to earlier theories, quantum metric is an inherent characteristic of many materials.
‘‘These discoveries open up new avenues for exploring and harnessing quantum geometry in a wide range of materials, with major implications for future electronics operating at terahertz frequencies (a trillion hertz), as well as for superconductivity and light–matter interactions,’’ concluded Andrea Caviglia.
Journal Reference:
Sala, G., et al. (2025) The quantum metric of electrons with spin-momentum locking. Science. doi.org/10.1126/science.adq3255