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Entangled Photons Maintained Under New York Streets

physics.aps.org

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Re: Entangled Photons Maintained Under New York Streets

#21

This is great but why can’t i get fiber internet in my bk apartment. Still struggling with spectrum coaxial pulling less than 5mbps today. No options on my block. Sheesh

Find a new apartment? Here's the FCC broadband map: https://broadbandmap.fcc.gov/home

[deleted]

Re: Entangled Photons Maintained Under New York Streets

#22
post #8

Earlier quoted context omitted.

Find a new apartment? Here's the FCC broadband map: https://broadbandmap.fcc.gov/home

Is this solution to every issue in the US? Like if something is shit then instead of fixing just run from the problem? I guess that’s why you are stuck choosing between republicans and democrats every 4 years lol.

"Why doesn't _EVERYONE_ move where broadband is!"

Except, uhhhhhhhhhhh, they can't.

Silicon Valley moment from gp

Re: Entangled Photons Maintained Under New York Streets

#23
post #7

Interesting, a sort of quantum eruv https://en.wikipedia.org/wiki/Eruv Does anyone have any additional context on the throughput numbers? It says 20k photons per second at 99% fidelity and 500k at 90%, but what is the actual bandwidth needed for reasonable usage / computation?

20k (10^4) photons/sec is a TINY amount. An ordinary flashlight emits something like 10^18 photons per second. Even a star in the night sky sends around 10^8 to your eye. That few photons is not going to have much bandwidth.

"20k photons at 99% fidelity" usually means "we can detect each of these 20k photons separately with 1% error rate", which would be roughly 20kb/s. Low bandwidth, but it has little to do with how much light comes from a flash light or from the night sky, because they are using detectors that detect each photon (as opposed our eyes or typical network equipment which might need a large average number of photons per bit).

Re: Entangled Photons Maintained Under New York Streets

#24
post #7

Interesting, a sort of quantum eruv https://en.wikipedia.org/wiki/Eruv Does anyone have any additional context on the throughput numbers? It says 20k photons per second at 99% fidelity and 500k at 90%, but what is the actual bandwidth needed for reasonable usage / computation?

20k (10^4) photons/sec is a TINY amount. An ordinary flashlight emits something like 10^18 photons per second. Even a star in the night sky sends around 10^8 to your eye. That few photons is not going to have much bandwidth.

AIUI, this sort of system is likely to end up a lot like TLS negotiation and asymmetric crypto in general. Even if it never has very much bandwidth, the ability to share secrets on a channel that is not just declared secure by engineers, but declared secure by physics has some advantages. Asymmetric crypto is generally atrociously slow too, but incredible useful because we can use it to bootstrap symmetric crypto which is very fast.

Of course, if it does upgrade to the point that it can move gigabits per second, they'll use it for that. I don't know of a particular reason why this would be fundamentally impossible. I'm just saying that's not a necessary condition for the technology to be useful.

Re: Entangled Photons Maintained Under New York Streets

#26
post #11
post #6

Earlier quoted context omitted.

In a public area you can not transport objects, the intention being that the Sabbath is a day of rest, and you should stay home or at least near your home and not do work. Note: Jewish law very carefully defines "public area", and it would take several pages of text to fully explain it, so before objecting be aware you may be lacking background knowledge.

I’m guessing it’s the cubits that gave pause more than the restriction. I first became aware of eruvim thanks to an article in the L.A. Times which talked about a new eruv being constructed in Venice. The article talked about the restriction on carrying and how the eruv allowed congregants to bring their keys¹ with them while attending synagogue. ⸻ 1. Doubtless someone reading this is thinking, well, they could just…

Keys on shabbat is doable without an eruv¹²³. (It's not considered carrying if it's an integral part of your clothing.) Eruvs are more for strollers/carrying small kids, dessert/wine when invited for lunch, etc.

¹https://thekeybelt.com

²https://www.judaica-world.com/index.php/adjustable-shabbos-k...

³https://maps.app.goo.gl/ptpGhwLeckdUTjUd7

Re: Entangled Photons Maintained Under New York Streets

#27

Earlier quoted context omitted.

Find a new apartment? Here's the FCC broadband map: https://broadbandmap.fcc.gov/home

Doesn't that map consider an entire region serviced if a single residence in that entire region can get the advertised speeds?

That is technically true but usually companies don't invest the kind of resources to support fiber just to service a handful of residences. Once the infrastructure is in place, you usually try to deploy it to as many homes as possible.

Re: Entangled Photons Maintained Under New York Streets

#29

How does one detect whether a pair is still entangled?

Easy-peasy. They will periodically see if the photons, when measured had already been measured by an eavesdropper. In quantum world measurement will affect the entangled system, so it’s impossible for someone to measure (read) the data in between without it being detected at both ends.

Re: Entangled Photons Maintained Under New York Streets

#30
post #26
post #11

Earlier quoted context omitted.

I’m guessing it’s the cubits that gave pause more than the restriction. I first became aware of eruvim thanks to an article in the L.A. Times which talked about a new eruv being constructed in Venice. The article talked about the restriction on carrying and how the eruv allowed congregants to bring their keys¹ with them while attending synagogue. ⸻ 1. Doubtless someone reading this is thinking, well, they could just…

Keys on shabbat is doable without an eruv¹²³. (It's not considered carrying if it's an integral part of your clothing.) Eruvs are more for strollers/carrying small kids, dessert/wine when invited for lunch, etc. ¹ https://thekeybelt.com ² https://www.judaica-world.com/index.php/adjustable-shabbos-k... ³ https://maps.app.goo.gl/ptpGhwLeckdUTjUd7

Yeah, this is covered in the Eruv wikipedia article as well, but was not mentioned in the L.A. Times article (at least as far as I can remember—it’s been 15+ years since I read it).
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