
A new antenna using single atoms could usher in the age of atomic radio - vezycash
https://arstechnica.com/science/2018/09/a-new-antenna-using-single-atoms-could-usher-in-the-age-of-atomic-radio/
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deckar01
The phrase "single atoms" seems misleading. The article describes the primary
device as a cell containing a vapor that needs a laser to activate the gas and
a laser to measure the gas. As far as I can tell the only thing "single" here
is that the vapor consists of one type of element, which doesn't seem like an
important piece of information for the title.

Edit: "single atoms" -> "gas and lasers"

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deckar01
Here is an alternate source with more concise details and a nice diagram of
the lasers and the cell.

[https://www.technologyreview.com/s/611977/get-ready-for-
atom...](https://www.technologyreview.com/s/611977/get-ready-for-atomic-
radio/)

~~~
yazan94
This is really interesting, but I am a bit confused on the practical
implementation. How could this be used to replace real-life systems? If I
understood it correctly, a potential system would be made up of lasers at the
transmitters, and a cloud of Rydberg atom gas at the receiving end plus a
specifically tuned laser to saturate the gas.

But this design runs into line-of-sight issues between the receiver and
transmitter. Also, the Rydhberg gas needs to be contained in some way that
will hold the gas in whatever place it needs to be but also be transparent
such that the transmitting laser can impact the gas as required without
interference from the containing medium.

I feel like this is conceptually cool, but not useful/practical outside of a
lab or unrealistically perfect outdoors environment. Does anyone know of any
uses for this new tech?

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deckar01
The signals are not transmitted with lasers, they are transmitted with
traditional RF broadcasting equipment. This is just an AM/FM radio receiver
that detects RF with lasers. The breakthrough is that it doesn't require a
physical antenna proportional in size to the wavelength of the frequency it is
detecting.

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princekolt
Interesting. But I had never before heard a description of RF ranges in
octaves. I suppose it makes sense, but that completely threw me off because I
thought they were talking about sound waves for a second.

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bcaa7f3a8bbc
> never before heard a description of RF ranges in octaves

you can read something about filter designs...

> _It is usual to measure roll-off as a function of logarithmic frequency,
> consequently, the units of roll-off are either decibels per decade (dB
> /decade), where a decade is a 10-times increase in frequency, or decibels
> per octave (dB/8ve), where an octave is 2-times increase in frequency. _

[https://en.wikipedia.org/wiki/Roll-off](https://en.wikipedia.org/wiki/Roll-
off)

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aj7
The market price for a pair of tunable lasers to do this is more than $100k.

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jtbayly
Very small, but needs a large “backup system”? So, not very small. And what
exactly is this backup system?

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jtbayly
Ok, I've been downvoted. But I'm still curious what in the world could be
considered a "backup system" but also necessary for implementing the
technology. Anything necessary for it to work isn't a "backup" is it?

And I'm also still curious what this particular large "backup system" is.

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rdlecler1
Does that mean we should have SETI looking into other channels?

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madengr
Antenna engineer here. The metal antennas mentioned in the article are
resonant (standing wave) antennas. There is another class of antennas called
traveling waves, but still need to be about 1/2 wavelength to operate
efficiently.

That being said, antennas can be much smaller than 1/2 wavelength, but their
efficiency goes down. There is a theoretical limit trading off bandwidth and
efficiency for volume, called the Chu limit.

So it would be interesting how this technique compares. It says it’s narrow
band, so like a laser, which means it may still be limited.

There are other methods, such as bouncing a laser off a thin metal membrane,
which supposedly has very low noise. Wonder how noisy this method is?

Antenna noise temperature is related to efficiency, but this is an active
antenna. So it really boils down to bandwidth vs. noise temperature per
volume. That metric would give an indication of how it compares to classical
antennas.

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dredmorbius
Any introductory reading you might recommend?

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madengr
There are a couple of books on electrically small antennas, but those are not
introductory. Stutzman and Theile is a good antenna textbook, and there are
many others; John Krause for example.

You could start with the ARRL Antenna Compendium, for non-engineering books.

Steven Best has some good papers (i.e. the spherical folded dipole), if you
have access to IEEE Xplore. The APS magazine articles are very good.

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dredmorbius
I meant basic, standard, antenna engineering.

Though the small stuff is also interesting.

Thanks.

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escherplex
Might want to try

 _Antenna Theory - Analysis and Design - Balanis (2016)_

But noticed a 2005 3rd edition is available in .pdf for download gratis at:

[https://archive.org/details/AntennaTheoryAnalysisAndDesign3r...](https://archive.org/details/AntennaTheoryAnalysisAndDesign3rdEd)

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dredmorbius
Thanks, this and the above are a good start.

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megamindbrian2
We can create life in a lab. And we also create new realities on a computer.
How long before we create a new reality in a lab and life on a computer?

