United States has developed a new method for studying disorder in superconductors using terahertz light pulses. By adapting techniques from nuclear magnetic resonance to terahertz spectroscopy, they were able to observe how disorder evolves in superconductors up to the transition temperature for the first time. Their findings, published in *Nature Physics*, shed light on the role of disorder in high-temperature superconductors, like cuprates, where chemical doping introduces variations that influence their properties.
Traditionally, studying such disorder has been challenging, especially near the superconducting transition temperature, as most techniques require extremely low temperatures and offer limited insights at higher temperatures. This new method, however, allows researchers to investigate superconductors near the transition point, using two-dimensional terahertz spectroscopy (2DTS) in a non-collinear geometry to capture terahertz nonlinearities.
In their study of the cuprate superconductor La1.83Sr0.17CuO4, the team observed a phenomenon they called “Josephson echoes,” which revealed that disorder in superconducting transport was lower than previously detected by other methods. Remarkably, disorder remained stable up to 70% of the transition temperature.
This breakthrough opens up new possibilities for exploring other superconductors, quantum materials, and short-lived states of matter that were previously inaccessible with conventional techniques.
