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Get Ready For Atomic Radio (technologyreview.com)
An anonymous reader quotes a report from MIT Technology Review: David Anderson at Rydberg Technologies in Ann Arbor, Michigan, and a couple of colleagues, have reinvented the antenna from scratch. Their new device works in an entirely different way from conventional antennas, using a laser to measure the way radio signals interact with certain types of atoms. The secret sauce in the new device is Rydberg atoms. These are cesium atoms in which the outer electrons are so excited that they orbit the nucleus at great distance. At these distances, the electrons' potential energy levels are extremely closely spaced, and this gives them special properties. Indeed, any small electric field can nudge them from one level to another. Radio waves consist of alternating electric fields that readily interact with any Rydberg atoms they come across. This makes them potential sensors.
But how to detect this interaction? A gas made of Rydberg atoms has another property that turns out to be useful -- it can be made transparent by a laser tuned to a specific frequency. This laser essentially saturates the gas's ability to absorb light, allowing another laser beam to pass through it. However, the critical frequency at which this happens depends crucially on the properties of the Rydberg atoms in the gas. When these atoms interact with radio waves, the critical frequency changes in response. That's the basis of the radio detection. Anderson and co create a gas of cesium atoms excited into Rydberg states. They then use a laser tuned to a specific frequency to make the gas transparent. Finally, they shine a second laser through the gas and measure how much light is absorbed, to see how the transparency varies with ambient radio waves. The signal from a simple light-sensitive photodiode then reveals the way the radio signals are frequency modulated or amplitude modulated. The atomic radio can detect a huge range of signals -- over four octaves from the C band to the Q band, or wavelengths from 2.5 to 15 centimeters. It also should be less insensitive to electromagnetic interference due to its lack of conventional radio circuitry. "The atomic radio wave receiver operates by direct real-time optical detection of the atomic response to AM and FM baseband signals, precluding the need for traditional de-modulation and signal-conditioning electronics," say Anderson and co.
But how to detect this interaction? A gas made of Rydberg atoms has another property that turns out to be useful -- it can be made transparent by a laser tuned to a specific frequency. This laser essentially saturates the gas's ability to absorb light, allowing another laser beam to pass through it. However, the critical frequency at which this happens depends crucially on the properties of the Rydberg atoms in the gas. When these atoms interact with radio waves, the critical frequency changes in response. That's the basis of the radio detection. Anderson and co create a gas of cesium atoms excited into Rydberg states. They then use a laser tuned to a specific frequency to make the gas transparent. Finally, they shine a second laser through the gas and measure how much light is absorbed, to see how the transparency varies with ambient radio waves. The signal from a simple light-sensitive photodiode then reveals the way the radio signals are frequency modulated or amplitude modulated. The atomic radio can detect a huge range of signals -- over four octaves from the C band to the Q band, or wavelengths from 2.5 to 15 centimeters. It also should be less insensitive to electromagnetic interference due to its lack of conventional radio circuitry. "The atomic radio wave receiver operates by direct real-time optical detection of the atomic response to AM and FM baseband signals, precluding the need for traditional de-modulation and signal-conditioning electronics," say Anderson and co.
Nobody has cared about radio for 15 years. Inventing a new form of radio is interesting but pointless.
So you don't use a smartphone or a wireless router, or any form of wireless transmission? You don't care because radio is everywhere.
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
actual news for nerds!
doesn't necessarily have to be radioactive to be excited. electrons get excited for a variety of reasons. birthdays, the color periwinkle blue, experience electricity with a potential hot date. that sort of thing.
Why is this better than current radio?
Replace an antenna the size of your hand, your arm, rabbit ears, a tower, ... with something you can mount on a chip in a tiny package on a PC board.
Get rid of the noise, intermodulation, and other pathologies in the high gain amplification and filtering of the tiny amount of energy picked up by that antenna, substituting a direct quantum-mechanical readout of the field, with high signal strength, only competing with noise from variations in the lasers' output as your starting point, feeding a strong signal to a more ordinary amplifier.
If it works out it could be a big deal in a tiny package.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way