Scientists at the National Institute for Standards and Technology in Gaithersburg, Maryland, have brought us one step closer to “atomic radio” by using an atom-based receiver to make a stereo recording of music streamed into the laboratory—namely, Queen’s “Under Pressure.” They described their work in a new paper in AIP Advances.
So-called “Rydberg atoms” are atoms that are in an especially excited state well above their ground (lowest-energy) state. This makes them extra-sensitive to passing electric fields, like the alternating fields of radio waves. All you need is a means of detecting those interactions to turn them into quantum sensors—like a laser. That means, in principle, that Rydberg atoms could receive and play back radio signals.
This isn’t the first time Rydberg atoms have been used for audio recording. Last September, we reported on the development of a new type of antenna capable of receiving signals across a much wider range of frequencies (more than four octaves) that is highly resistant to electromagnetic interference. Scientists at Rydberg Technologies zapped vapor cells filled with excited cesium atoms with laser light tuned to just the right critical frequency, essentially saturating the atoms to prevent them from absorbing any more light. The critical frequency at which this transition happens will change in response to a passing radio wave, so the light from that second laser beam will flicker in response.