Researchers have achieved a notable advance in materials science, overcoming longstanding limitations in terahertz microscopy to reveal previously unseen quantum behavior. A team at the Massachusetts Institute of Technology detailed in *Nature* today how they’ve refined the technique to observe electron movement within superconducting materials with unprecedented precision. This breakthrough, utilizing a novel method for generating and focusing terahertz pulses, opens new avenues for exploring and ultimately designing advanced materials with possibly revolutionary applications in energy and technology [[2]].
초전도체를 통과하는 전자의 집단적 파동의 모습을 상상해 묘사한 그림. Sampson Wilcox, Emily Theobald 제공
A team of U.S. researchers has overcome technical limitations in terahertz microscopy, a tool used to observe previously unobservable quantum properties of materials. The breakthrough promises to accelerate research in advanced materials and physics, particularly in the study of two-dimensional materials.
Researchers at the Massachusetts Institute of Technology (MIT), led by physics professor Nuh Gedik, successfully made precise observations of electron movement within two-dimensional superconductors using terahertz light. The findings were published on February 4th in the international academic journal Nature. doi.org/10.1038/s41586-025-10082-2
Terahertz light oscillates more than one trillion times per second. Like X-rays, it can penetrate various materials, including fabrics, wood, plastics, ceramics, and thin bricks, but it does so safely for humans and biological tissues. This characteristic makes it a promising technology for applications in security screening and medical imaging.
However, terahertz light’s wavelength – approximately several hundred micrometers (µm, where 1 µm is one millionth of a meter) – has historically limited its use in microscopy due to insufficient resolution for observing the movements of the microscopic world. Observing objects smaller than the wavelength of light is fundamentally impossible. As the researchers explained, this limitation meant missing out on quantum phenomena characteristic of the terahertz frequency range.
The MIT team circumvented this resolution barrier by utilizing a structure capable of generating terahertz pulses. These pulses are bursts of light energy concentrated in a short period of time. The structure consists of multiple, extremely thin layers of metal, which, when illuminated with a laser, create a cascading effect that emits pulses corresponding to terahertz frequencies.
By positioning a sample very close to the pulse-emitting structure and then shining a laser onto it, the terahertz pulses interact with only a small portion of the electrons within the sample. By slightly shifting the laser’s position and scanning the sample, the team effectively scanned a region smaller than the wavelength of the terahertz light. This is analogous to placing a sample on a terahertz light “flashlight” and moving the flashlight around to capture an image.
The researchers implemented their idea by creating a terahertz microscope and using it to image bismuth strontium calcium copper oxide (BSCCO), a two-dimensional material. They cooled the material to extremely low temperatures, inducing a superconducting state where electrical resistance disappears, and then made their observations.
The experiment resulted in the first-ever detection of “two-dimensional superconducting plasmons” – a collective movement of electrons – within BSCCO. This discovery, previously only theorized, could provide a crucial pathway for developing high-temperature superconducting materials, which operate at relatively warmer temperatures. The development of such materials could revolutionize energy transmission and storage.
The research team plans to apply the terahertz microscope to other two-dimensional materials to capture a wider range of quantum phenomena.
