A long-standing problem in seeing fast electron motion is solved, opening new paths for better superconductors and faster wireless systems.
Designers of superconducting systems face a simple problem: they cannot clearly see how electrons move and interact at very small sizes and very high speeds, which slows the development of better materials for efficient power transfer, fast computing, and high-speed communication. At the same time, existing tools cannot properly use terahertz light, which is needed to study these fast processes, because its long wavelength makes it hard to focus on tiny samples, causing important details to be missed.
MIT researchers have addressed these problems by building a new terahertz microscope that can probe quantum-scale motion directly. The system allowed them to observe collective vibrations of superconducting electrons inside a material called BSCCO, revealing behavior that had never been directly measured before.
These measurements exposed a frictionless flow of electrons moving together at terahertz frequencies. This confirms long-standing theoretical predictions and helps explain how superconductivity works at the microscopic level. Such insights are essential for developing materials that could operate as superconductors at higher temperatures.
The microscope overcomes the diffraction limit by generating sharp terahertz pulses using ultrathin spintronic emitters and placing samples extremely close to the source. This confines the terahertz field before it spreads, allowing it to interact with regions much smaller than its wavelength. A multilayer mirror filters unwanted light and protects sensitive samples from laser exposure.
Using this setup, the team scanned a thin BSCCO sample cooled near absolute zero and detected strong changes in the terahertz signal caused by electron motion. The distorted signal revealed that the material itself was emitting terahertz radiation in response, caused by collective electron vibrations.
Beyond superconductors, the same tool can help researchers study fast processes in many advanced materials, including two-dimensional systems, magnetic materials, and nanoscale electronic devices. This could support the design of faster wireless links, compact terahertz sensors, and microscopic antennas.
Terahertz radiation is safe, non-ionizing, and can pass through materials such as plastic, fabric, wood, and ceramics. By making terahertz imaging practical at microscopic scales, this new microscope removes a long-standing barrier in both fundamental research and applied technology development.
