The science of the very small could lead to a better understanding of something much larger ? the universe itself ? suggests a paper online this week in Nature Nanotechnology.
Of all the photons of light emitted since the Big Bang, 98% have wavelengths in the terahertz region of the electromagnetic spectrum ? a region between far infrared and microwaves. These photons are strongly absorbed by the Earth's atmosphere, which is why terahertz telescopes based in space are crucial for astrophysics research. However, the photon detectors on future advanced telescopes need to be at least 100 times more sensitive than the current state of the art.
Michael Gershenson, Boris Karasik and co-workers have now built such a detector with a nanosized island of titanium connected to niobium nanowires. The titanium nano-island becomes superconducting (which means it loses its resistance to electrical current) when cooled to within 0.2 degrees of absolute zero. The highly sensitive nature of the device ? which is known as a hot-electron superconducting nanobolometer ? is due to its exceptional thermal isolation from its surroundings and its extremely small heat capacity.