Scientists Create Quantum Sensor That Covers Entire Radio Frequency Spectrum (phys.org) 64
A quantum sensor could give Soldiers a way to detect communication signals over the entire radio frequency spectrum, from 0 to 100 GHz, said researchers from the Army. Such wide spectral coverage by a single antenna is impossible with a traditional receiver system, and would require multiple systems of individual antennas, amplifiers and other components. Phys.Org reports: In 2018, Army scientists were the first in the world to create a quantum receiver that uses highly excited, super-sensitive atoms -- known as Rydberg atoms -- to detect communications signals, said David Meyer, a scientist at the U.S. Army Combat Capabilities Development Command's Army Research Laboratory. The researchers calculated the receiver's channel capacity, or rate of data transmission, based on fundamental principles, and then achieved that performance experimentally in their lab -- improving on other groups' results by orders of magnitude, Meyer said.
"These new sensors can be very small and virtually undetectable, giving Soldiers a disruptive advantage," Meyer said. "Rydberg-atom based sensors have only recently been considered for general electric field sensing applications, including as a communications receiver. While Rydberg atoms are known to be broadly sensitive, a quantitative description of the sensitivity over the entire operational range has never been done." To assess potential applications, Army scientists conducted an analysis of the Rydberg sensor's sensitivity to oscillating electric fields over an enormous range of frequencies -- from 0 to 1012 Hertz. The results show that the Rydberg sensor can reliably detect signals over the entire spectrum and compare favorably with other established electric field sensor technologies, such as electro-optic crystals and dipole antenna-coupled passive electronics. The findings have been published in the Journal of Physics B: Atomic, Molecular and Optical Physics.
"These new sensors can be very small and virtually undetectable, giving Soldiers a disruptive advantage," Meyer said. "Rydberg-atom based sensors have only recently been considered for general electric field sensing applications, including as a communications receiver. While Rydberg atoms are known to be broadly sensitive, a quantitative description of the sensitivity over the entire operational range has never been done." To assess potential applications, Army scientists conducted an analysis of the Rydberg sensor's sensitivity to oscillating electric fields over an enormous range of frequencies -- from 0 to 1012 Hertz. The results show that the Rydberg sensor can reliably detect signals over the entire spectrum and compare favorably with other established electric field sensor technologies, such as electro-optic crystals and dipole antenna-coupled passive electronics. The findings have been published in the Journal of Physics B: Atomic, Molecular and Optical Physics.
Soldiers? (Score:5, Insightful)
Is it only "soldiers" that would need this?
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Is it only "soldiers" that would need this?
Like FM radio, it will be built into your cell phone, but inaccessible by any apps.
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Is it only "soldiers" that would need this?
Like FM radio, it will be built into your cell phone, but inaccessible by any apps.
I assume you're joking, but just in case... There's at least one app that can access the FM receiver in your Android phone, if it has one -- Apple iPhones apparently don't have an FM chip, or it's locked down. My Kyocera HydroVIBE has an FM chip and I use the Next Radio [google.com] app to listen to over-the-air radio. Unfortunately, while the app is still available on the Google Play Store, I believe development has ceased as, according to a quick Google search, the company wasn't able to sufficiently monetize the app
Re: Soldiers? (Score:1)
Soldiers. David works for the army. He doesn't care about anything else.
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I was bother by the phrase "...giving Soldiers a disruptive advantage" as well. His wording suggests he's after some more pork.
Re: Soldiers? (Score:2)
This type of pork requires more study though.
Building radios smaller benefits everyone
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Is it only "soldiers" that would need this?
The insane ones want their wars and their ability to apply violence whenever they chose.
Re:Soldiers? (Score:4, Interesting)
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And passive radar/lidar that works on ambient radiation.
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Re: Soldiers? (Score:1)
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The police and other security will definitely want this.
Most civilians do not need to know what everyone else is saying or where they are.
But I can easily see law enforcement and corporate security wanting to know what and where everyone is broadcasting.
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Might be kinda nice to have a receiver that can pick up AM, FM, digital radio, digital TV and mobile phone signals though, hey?
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The thing is, an ordinary antenna somewhat filters the incoming signal. The attached variable capacitor is used to determine which wavelengths will be amplified.
It sounds as if this approach would have a real problem with noise. Perhaps digital signal processors have gotten good enough that this wouldn't matter, though.
OTOH, if it can, as I expect, transmit as well as receive it would make a great spread spectrum transmitter, and to read the signal you'd need the correct decryption key. Perhaps that coul
Re: Soldiers? (Score:1)
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Can you give me a link? The antennas I'm familiar with all depend on being resonant with the wavelength of interest. Well, the series of wavelengths...full, half, quarter, etc.
Practical? (Score:1)
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Replying to remove accidental mod. The stupid Javascript locks in the first mod in the list if navigating by keyboard.
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And are we talking room temperature sensor, or are you going to have to feed your radio on liquid helium? Quantum anything usually means cold.
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But I haven't read and comprehended the entire thing yet. If you're inclined to do, I've found the full paper here: https://arxiv.org/pdf/1910.006... [arxiv.org]
In a different paper by different authors: https://iopscience.iop.org/boo... [iop.org] on page 21 of the PDF reader or respectively 11 of the paper they write:
Correction to quoted frequency range. (Score:1)
> ... oscillating electric fields over an enormous range of frequencies -- from 0 to 1012 Hertz.
No -- according to the linked article, it's 0 to 100 GHz (meaning 100 * 10^12 Hz). The quoted range of 0 to 1012 Hz would not be enormous, it would be trivial.
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Sorry, I meant 100 * 10^9 Hz.
Re:Correction to quoted frequency range. (Score:5, Informative)
Source: https://iopscience.iop.org/art... [iop.org]
Those are really impressive ranges.
Also don't just trust the articles. Always also check out the scientific paper if possible.
Re: Correction to quoted frequency range. (Score:5, Informative)
This is Slashdot.
You'd be lucky if they read TFS!
Re: Correction to quoted frequency range. (Score:4, Funny)
Normal Slashdot user: Does not RTFA.
Advanced Slashdot user: Does not RTFS.
Expert Slashdot user: Does not read the headline and just starts posting endless swastika banners.
Re: Correction to quoted frequency range. (Score:2)
Nah mate.
Guru Slashdot reader: Never reads even TFHeadline, but can predict what it's about from the first comments, and comment accordingly, ... or just post a comment that fits everything.
Everything that happens, has happened before. You learn to smell the patterns.
Haven't read anything but comments in five years. True story. *lifts glass*
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Cool. BTW: I really miss your swastika banners.
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Actually, the range 0...1012Hz has the same size as 0...100GHz, as there is no lower limit here and hence both are infinite. As to usefulness, RF communication starts meaningfully somewhere in the kHz range.
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0 is a lower limit, it accounts for no EM oscillation at all, still if you aren't specifying the increment... But 1khz isn't going to detect a wifi signal. The 0 to 10^12hz in the article will though, which if you copy and paste without paying attention the carat gets eaten and it becomes 0 to 1012hz
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You are wrong. You need to use log-scale for a frequency range and then 0 is not a lower limit. But I guess you do not have a background in signal processing.
Incidentally, I very much intentionally copied the 1012Hz as stated to make a point.
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You are wrong, negative frequencies have no meaning in this context. 0, infinite wavelength, is the lower limit of the EM spectrum. Incidentally, a wavelength longer than the observable universe's diameter is impossible.
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You still do not understand. The lower limit is indeed 0, but it cannot be reached and hence you have an infinite "amount" of spectrum between any non-zero frequency and that lower limit. (I never said anything about "negative" frequencies....) As I said, you obviously have no understanding of signal processing.
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Funny I do signal processing every day, get off your high horse. Your log scale is not appropriate for many real world situations. I'm only saying theoretical lower limit is 0 Hz and not any other number of Hz.
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Funny I do signal processing every day
Well, that makes it worse. In that case you are _incompetent_. Not really a surprise.
I'm only saying theoretical lower limit is 0 Hz and not any other number of Hz.
Yes, obviously. Has anybody here claimed any different?
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Indeed. I was merely pointing out that "size" of a frequency range starting a 0 is not a meaningful measure.
Re: Correction to quoted frequency range. (Score:1)
SETI (Score:4, Interesting)
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Re:SETI (Score:5, Insightful)
I think the utility of this is the small size. They compare its sensitivity to dipole antennas but don't give numbers.
How useful it would be for the extremely weak signals being picked up by radio telescopes I don't know. For them sensitivity is the most important factor.
So they have an antenna... (Score:5, Insightful)
Ok, they can detect signals over a huge range. It is going to take a heck of a lot to process all that noise and find the signals. Modern spread spectrum and frequency hopping protocols aren't exactly the shiny beacon on the hill that old analog radio signals were, so a broad range sensor is just the first step in developing technology that will be disruptive on the battlefield.
It will be immediately useful to allow much more versatile receivers for our own transmissions, but that is just another incremental step in miniaturization and versatility. The real disruption potential here is listening in on the enemy, and that will require some pretty smart AI to find the signals in the noise, then a huge amount of number crunching to decrypt it.
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"The real disruption potential here is listening in on the enemy, and that will require some pretty smart AI to find the signals in the noise, then a huge amount of number crunching to decrypt it."
Or... quantum computation of all the possibilities in parallel
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In fairness this sensor technology is the result of somebody looking into pixieland and quantum computing does exist in reality even if quantum supremacy hasn't been achieved. I don't know that anybody is claiming this actually works well enough to be feasible yet anyway.
https://thenextweb.com/artificial-intelligence/2018/03/06/google-reclaims-quantum-computer-crown-with-72-qubit-processor/
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So wow to process that enormous channel capacity is indeed a good question to which quantum computing doesn't sound like an informed answer.
As far as I understand Rydberg atoms only work as receivers so far. Hence we can't produce such a wide spectrum for transmitters. For that we have to rely on more traditional methods that produce narrow bandwidths.
So unless we have trans
Ridiculous (Score:2)
Let's not act as if that possibility was so far off.
This doesn't even require a general quantum computer. Just a specific object that transforms the incoming wavefunction. E.g. a prism is an object that does fit that description. (But offers a different functionality than needed here.)
Re:So they have an antenna... (Score:4, Interesting)
The breakthrough is a wide bandwidth receiver that goes effectively from DC to daylight as a single small module. Typical radio receivers don't offer that much bandwidth, and even the fancy SDR radios often need a prescaler in front (a tuner) to select a narrower range of frequencies you're interested in before putting it into the ADC. The tuner basically discards the undesired frequencies.
If you can receive DC-Daylight without needing a tuner, you can record the entire spectrum at once for later decoding
And yes, the big thing with spread spectrum technology is noise immunity by basically being noise, and letting others in. All you see on any receiver is a slightly raised noise floor on the bands. The magic of spread spectrum is being able to recover a signal embedded in the noise below the noise floor. And yes, it works, since modern 3G (W-CDMA), 4G/LTE, old school CDMA, and GPS all effectively raise the noise floor and the signal is recovered from the noise. GPS is particularly interesting given the signal emitted by the satellite isn't particularly powerful and by the time your receiver gets it, it's below the natural noise floor, and there are up to 12 different satellites in that noise.
And yes, it's also why SETI is interesting because the Earth's radio transmissions have been diminishing - whereas maybe 100 years ago we were transmitting powerful narrowband signals well above the noise floor, these days we've increased transmission efficiency and used less and less power to transmit such that the vast majority of emissions are barely above the noise floor. It's easy to detect beacons because it's a distinct signal, but spread spectrum looks like noise unless you know what you're looking for.
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>>If you can receive DC-Daylight without needing a tuner, you can record the entire spectrum at once for later decoding
That is good in theory, but how exactly do you record that? The analog world is gone, and there was never an analog medium with that bandwidth anyway. An antenna does not a receiver make. To "record" that complete spectrum would require a AtoD device with a sample rate of vaguely twice the period of the highest frequency you wanted to examine.
I don't know much about DSP, but my gen
Decrypt it, or destroy it (Score:2)
There are applications where the military wishes to destroy the radar site pinging your plane, or find the enem troops. Sometimes finding the signal from the guys trying to kill you is enough - no decryption needed.
Having said that, now I have to go figure out how to decrypt some public key crypto. Post grad classes at top institutions are hard :(
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Sometimes all you need to do is locate the transmitter with a simple direction finder.
And whatever one side can disrupt, so can the other, I hope. I don't want to be at such a disadvantage to the average fascist dictator.
ahem... (Score:2)
There is a rather obvious and large copy and past error here.
"from 0 to 10^12 Hertz"
not
from 0 to 1012 Hertz
Capital (Score:2)
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Because the citation actually comes from the Army Research Laboratory.
SciFi Haters (Score:1)
"Scan on all frequencies" used to be derided by some nerds who "knew" that antennas of different lengths were required for such "nonsense".
If anything the phrase is redundant now because "scanning" will just become all frequencies by default.
Suck it, killjoys.
Noise Temperature (Score:4, Insightful)
Mistake or fake news? (Score:1)
Heathkit (Score:1)
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(Somehow the edit link has disappeared.)
Go back to facebook (Score:1)