Army Builds Wideband DC to 20 GHz Quantum Receiver

Back in July 2019 we posted about a new development in radio technology known as "Atomic Radio" or "Quantum Radio". In that post we discussed an article that explained the concept and science behind the idea and noted how some researchers described the possibility of a very wideband capable receiver.  

Recently the US Army has described how they built a quantum radio that can receive from DC to 20 GHz. If you're interested in the science, the paper is published in the Journal of Physics B: Atomic, Molecular and Optical Physics and it is available on sci-hub. The radio uses something called a Rydberg sensor which they describe below. 

The Rydberg sensor uses laser beams to create highly-excited Rydberg atoms directly above a microwave circuit, to boost and hone in on the portion of the spectrum being measured. The Rydberg atoms are sensitive to the circuit's voltage, enabling the device to be used as a sensitive probe for the wide range of signals in the RF spectrum.

Army researcher Kevin Cox notes how this is the first implementation that can operate over such a wide frequency range:

"All previous demonstrations of Rydberg atomic sensors have only been able to sense small and specific regions of the RF spectrum, but our sensor now operates continuously over a wide frequency range for the first time," said Dr. Kevin Cox, a researcher at the U.S. Army Combat Capabilities Development Command, now known as DEVCOM, Army Research Laboratory. "This is a really important step toward proving that quantum sensors can provide a new, and dominant, set of capabilities for our Soldiers, who are operating in an increasingly complex electro-magnetic battlespace."

Quantum radios may be one of the next big leaps in radio technology. However as they require lasers and the space of a small laboratory the technology will probably be restricted to the military and institutions for the time being.

A Rydberg sensor setup (LEFT), The experimental setup for a Rydberg Quantum Radio Receiver (RIGHT)
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I hear quantum radio receivers are suppose to be much more sensitive than conventional receiver designs. I wonder what kind of sensors and detection devices could be made from this technology? Certainly ground penetrating radar, radio astronomy and SIGINT would benefit greatly from this. I wonder what else?


Happy to see that – apparently – this gadget requires no cryogenics … that spoils a lot of QM device fun. Can’t wait to see it out in a chipset!

Interested to see what the actual path will be for a typical (HF) antenna into the Rydberg device.


I’ve read the paper. The novel part of this is not so much a receiver as a tuner. And it’s a tuner with 4 MHz bandwidth. Yes, it can tune over a wide range but it’s bandwidth is slightly less than 2x of an rtl-sdr. Furthermore, it requires a normal antenna to feed the coplanar waveguide/rydberg atom device. That means it’s tunable range is constrained by the antenna and not the tuner as is normal.

Kenneth Coble

let me know when i can buy one for less than 300 american dollars, plug a usb or ethernet cable into it and get a nice spectrum & waterfall with all mode reception


Given our ability to make laser diodes and the remarkably uncomplex beam path up there, I wouldn’t be surprised to see this portable and commercialized in less than 10 years.

It’s lab sized because it’s experimental and one-off.


What will you use for your power source to vaporise the rubidium they used as the atom in their Rydberg sensor.


Diode laser and a battery. When it’s a production device, we’re talking about vaporizing a few atoms in a vacuum chamber the size of a pinhead, not a giant lab chamber.


Once the Chinese get a hold of this, we’ll see it in a USB dongle for $20 on Amazon.


probably already available – as a dud


Show me the DC to 20GHZ antenna connected to it and I will sit up and take some notice.


It is shown in the image above, it is nothing like a traditional antenna. The Rydberg sensor is detecting oscillating electric fields. From the paper “Highly excited Rydberg atoms are perturbed by an incident RF field. These perturbations shift the atomic energy levels and are detected using optical spectroscopy and directly produces optical spectroscopy”. In theory with no Johnson–Nyquist noise, this could be one super sensitive receiver.


Oh, so…magic. All you had to say was “it’s magic.” 🙂

Seriously, though, this is pretty impressive, even if the science is beyond my ken.


From the paper:

Attaching a standard rabbit-ears antenna, the spectrum analyzer detects weak ambient signals including FM radio, AM radio, WiFi, and bluetooth.