3 ms·

What we've got here is a lot of marketing fluff around a Rydberg spectrum analyzer.[1][1a]. This is essentially an RF mixer[2] which, according to [1a]: riva

What we've got here is a lot of marketing fluff around a Rydberg spectrum analyzer.[1][1a]. This is essentially an RF mixer[2] which, according to [1a]: rivals the performance of commercially-available spectrum analyzers with high sensitivity, 4 MHz instantaneous bandwidth, and over 80 dB of linear dynamic range. While 80 dB of linear dynamic range is good, there are other designs, such as the Tayloe mixer[3][4] that are more sensitive and have a better dynamic range due to their inherently linear nature. Careful reading of the linked paper shows that their best sensitivity measurements rely on conventional external low noise amplifiers. So, this is mostly grant writing driven marketing. We've been getting signal detection this good with tube based WW2 and later ham gear my friend repairs. It's not uncommon to detect 0.1 μV signals, which is -127 dBm. These receivers have approximately 2khz of bandwidth -127 dBm - 10*Log(2000) --> -160dBm/Hz. So, lots of interesting tangents, but nothing world changing as of now. [1] https://arxiv.org/abs/2009.14383 https://arxiv.org/abs/2009.14383 [1a PDF] https://arxiv.org/pdf/2009.14383.pdf https://arxiv.org/pdf/2009.14383.pdf [2] https://en.wikipedia.org/wiki/Frequency_mixer https://en.wikipedia.org/wiki/Frequency_mixer [3 pdf] https://www.norcalqrp.org/files/Tayloe_mixer_x3a.pdf https://www.norcalqrp.org/files/Tayloe_mixer_x3a.pdf [4] https://pa3fwm.nl/technotes/tn17c.html https://pa3fwm.nl/technotes/tn17c.html

fsh 4y ago
One principal advantage is that the laser-cooled atoms are unaffected by Johnson noise which sets the ultimate limit in semiconductor (or vacuum tube) based systems. However, their stated sensitivity of -120 dBm/Hz is more than 50 dB above the Johnson noise at room temperature. They have a lot of work to do until this becomes relevant.
rpaddock 4y ago
The Tayloe et.al. look a lot like Dr Sutton's work for NASA on his Synchronous Demodulator. "Improved Analog Synchronous Demodulator: Output ripple is suppressed without an output filter" GSC-13179, NASA Tech Briefs, March 1992. Uses dual op-amp and 4053 CMOS switches. "Digital Synchronous Demodulator: The digital version offers greater speed, precision, and reliability." GSC-13273. Here Dr Sutton corrects me for mixing two of his unrelated NASA projects: "Hi Bob, The synchronous detectors were used in temperature monitors and temperature controllers designed to control temperatures on spacecraft at 60 milliKelvin +/- a few ucroKelvin. The preamplifier had to have a gain of 10E5 after which the demodulated signal had to be converted by a 16 bit ADC, with +/- 1LSB allowable error.... so of course, you can see that we were working with extremely small signals buried in the noise, and we had to go all out in an effort to beat down the noise. That's why we had to use a new improved synchronous demodulator. This project was as close to being impossible as you can get! I still have trouble believing that we actually made it work. The active ("Black Hole") antenna was developed in another project, where we didn't want to transport a two meter long antenna that weighed 200 pounds.....so we miniaturized the hardware while simultaneously expanding the antenna field cross section. We wanted to receive the entire ELF-VLF bands all at once, so we had to have an extremely broadband antenna....like four decades of bandwidth or more. You wouldn't believe the arguments I had with the reviewer at Physics Essays. He just couldn't believe that one could do what we did....and if it was indeed true, then why hadn't someone done it years ago?.., "and what makes you so smart", .so, of course, "this must be nonsense, etc....." Progress in physics is so bloody difficult because most physicists think that everything worthwhile has already been discovered....so they expect nothing new. This is negative feedback which, of course, makes the system stable, I suppose." - John Sutton, Ph.D. https://web.archive.org/web/20101201225337/http://unusualresearch.com/Sutton/sutton.htm https://web.archive.org/web/20101201225337/http://unusualres...
- mikewarot 4y ago
  There are some strong similarities, that's for sure. The phasing is wired completely different between the two, leading to different behavior. It looks like Suttons work is a new variation of the chopped amplifier, a classic scheme for canceling out DC bias in instrumentation amplifiers.
rpaddock 4y ago
"...marketing fluff around a Rydberg spectrum analyzer..." How about the price point? The paper speaks of DC to 1 THz. Any good spectrum analyzer I know of for anything close to that range, is going to have a lot of zeros in the price tag that puts it out of the budget of just about everyone. Even covering all of 5G or newer automotive RADAR at 77 GHz is out of most budgets.
- mikewarot 4y ago
  Marketing is not always about retail sales. Its a necessary evil ever since the Golden Fleece awards were used to neuter basic research. Grant proposals are more about a marketing push than science these days. The article and associated paper are really just fluff so that they can keep doing research in spite of incompetent oversight.

fsh 4y ago

One principal advantage is that the laser-cooled atoms are unaffected by Johnson noise which sets the ultimate limit in semiconductor (or vacuum tube) based systems. However, their stated sensitivity of -120 dBm/Hz is more than 50 dB above the Johnson noise at room temperature. They have a lot of work to do until this becomes relevant.

rpaddock 4y ago

The Tayloe et.al. look a lot like Dr Sutton's work for NASA on his Synchronous Demodulator. "Improved Analog Synchronous Demodulator: Output ripple is suppressed without an output filter" GSC-13179, NASA Tech Briefs, March 1992. Uses dual op-amp and 4053 CMOS switches. "Digital Synchronous Demodulator: The digital version offers greater speed, precision, and reliability." GSC-13273. Here Dr Sutton corrects me for mixing two of his unrelated NASA projects: "Hi Bob, The synchronous detectors were used in temperature monitors and temperature controllers designed to control temperatures on spacecraft at 60 milliKelvin +/- a few ucroKelvin. The preamplifier had to have a gain of 10E5 after which the demodulated signal had to be converted by a 16 bit ADC, with +/- 1LSB allowable error.... so of course, you can see that we were working with extremely small signals buried in the noise, and we had to go all out in an effort to beat down the noise. That's why we had to use a new improved synchronous demodulator. This project was as close to being impossible as you can get! I still have trouble believing that we actually made it work. The active ("Black Hole") antenna was developed in another project, where we didn't want to transport a two meter long antenna that weighed 200 pounds.....so we miniaturized the hardware while simultaneously expanding the antenna field cross section. We wanted to receive the entire ELF-VLF bands all at once, so we had to have an extremely broadband antenna....like four decades of bandwidth or more. You wouldn't believe the arguments I had with the reviewer at Physics Essays. He just couldn't believe that one could do what we did....and if it was indeed true, then why hadn't someone done it years ago?.., "and what makes you so smart", .so, of course, "this must be nonsense, etc....." Progress in physics is so bloody difficult because most physicists think that everything worthwhile has already been discovered....so they expect nothing new. This is negative feedback which, of course, makes the system stable, I suppose." - John Sutton, Ph.D. https://web.archive.org/web/20101201225337/http://unusualresearch.com/Sutton/sutton.htm https://web.archive.org/web/20101201225337/http://unusualres...

mikewarot 4y ago
There are some strong similarities, that's for sure. The phasing is wired completely different between the two, leading to different behavior. It looks like Suttons work is a new variation of the chopped amplifier, a classic scheme for canceling out DC bias in instrumentation amplifiers.

rpaddock 4y ago

"...marketing fluff around a Rydberg spectrum analyzer..." How about the price point? The paper speaks of DC to 1 THz. Any good spectrum analyzer I know of for anything close to that range, is going to have a lot of zeros in the price tag that puts it out of the budget of just about everyone. Even covering all of 5G or newer automotive RADAR at 77 GHz is out of most budgets.

mikewarot 4y ago
Marketing is not always about retail sales. Its a necessary evil ever since the Golden Fleece awards were used to neuter basic research. Grant proposals are more about a marketing push than science these days. The article and associated paper are really just fluff so that they can keep doing research in spite of incompetent oversight.