MIT
Technology Review: The ability to detect increasingly faint
radio signals is important in a wide range of cutting-edge
technologies, including radio astronomy, navigation, and
medical imaging. At the smallest spatial scales, filtering out
noise often requires cooling detectors with liquid
helium. Tolga Bagci of the University of Copenhagen,
Denmark, and his colleagues have developed a proof-of-concept
nanoscale radio wave receiver that minimizes noise without
cooling and converts the radio signal to light. They created a
capacitor from a silicon nitride membrane coated with a layer
of reflective aluminum and suspended above an electrode. Then
they inserted the capacitor into a circuit that resonates at
specific radio wave frequencies. When the circuit detected
radio waves, it caused the membrane to vibrate. A laser
reflecting off the aluminum layer recorded the vibrations as
optical phase shifts. The result was a receiver with a
room-temperature sensitivity better than any receiver that used
ultralow temperatures.
