Light slows down carbon nanotubes in water

Researchers demonstrated that water-suspended carbon nanotubes move more slowly when exposed to green light on June 10, 2026. This observation suggests that excited electrons within the nanotubes couple to the surrounding water molecules, a phenomenon they term 'quantum friction.' The study, published in Nature, utilized green light with a wavelength of 532 nanometers, which is known to excite electrons in carbon nanotubes. When these electrons absorb energy from the light, they enter a higher energy state. The researchers observed a measurable decrease in the diffusion coefficient of the nanotubes in water under this specific illumination. This effect was not observed with other wavelengths of light, indicating a specific interaction tied to the electronic excitation of the nanotubes. The team proposes that this quantum friction arises from the interaction between the energized electrons and the polar water molecules, leading to a dissipation of energy and a reduction in the nanotubes' motion. This finding could have implications for nanotechnology applications involving carbon nanotubes in liquid environments, potentially influencing their behavior in sensors, drug delivery systems, or advanced materials.