Researchers have developed a new readout scheme for Transition Edge Sensors (TES) that allows probing their timing properties at the sub-nanosecond scale. This advancement is crucial for applications requiring high-speed and high-precision particle detection, such as in particle physics experiments or the search for dark matter. TES are ultrasensitive cryogenic detectors that operate at temperatures near absolute zero, and their ability to measure tiny energy variations makes them ideal for detecting single photons and other low-energy particles.

The method employs a parallel SQUID-semiconductor readout scheme, combining the sensitivity of Superconducting Quantum Interference Devices (SQUIDs) with the speed of semiconductors. This configuration enables a detailed characterization of TES dynamics at extremely short timescales, revealing how they respond to detection events. Understanding these timing properties is fundamental for optimizing the design and performance of TES in future experiments.

The obtained results demonstrate the viability of this technique for unraveling the intrinsic mechanisms that limit the response speed of TES. By accurately characterizing the transient response of these sensors, scientists can identify bottlenecks and develop strategies to improve their speed without compromising their exceptional energy sensitivity. This work lays the foundation for a new generation of cryogenic detectors with unprecedented timing capabilities.