Quantum Internet Edges Closer As Researchers Teleport Photons Six Kilometers Away

Status
Not open for further replies.

alextheblue

Distinguished
Apr 3, 2001
3,078
106
20,970
2
If we build too many quantum systems and networks, we're going to lag the simulation. :( Keep it simple guys. Nobody likes stuttering. Imagine everything lagging while you're in traffic. Terrible!
 

Simon Anderson

Distinguished
Sep 22, 2013
76
0
18,630
0
hmm "dark fibre" is an existing term that just means a piece of fibre you own or lease, instead of purchasing bandwidth on someone else's existing network (more common). Are they adding a new definition or just using their dark fibre in a new way?

But something I don't understand about these entanglement experiments is how the two photons in the pair are actually separated... in layman's terms: do you put a photon in some sort of fancy "jar" that stops it from flying off and bouncing off the nearest cat photo, and physically transport it the 6 kilometers away to City Hall?

Perhaps their "dark fibre" is still traditional definition: it's a piece of fibre they own, and like article says, they have kept it "bare" without any equipment because that's what's needed for their experiment? The photon from the pair is actually transported on this dark fibre?

In order to be considered teleportation, whatever photon was sent down the dark fibre, would have to then be stored/contained in preparation for the experiment: the quantum transfer on information from university photon and the city hall photon... otherwise it's just sending light down fibre like any other fibre connection, but measuring it differently?

In other words, I would imagine, the eventual "end game" is to have a large number of permanent photo pairs spread all around the world: you change one half of pair and the other half changes *bam* instant information transfer... if you need to transfer the photons to their destination before hand, via "dark fibre" or whatever, it kinda defeats the purpose right? Or maybe there's an initial send of say 64 photons from 64 pairs via normally fibre optics, and then those 64 photon pairs are used for information transfer for a certain period of time?
 

InvalidError

Titan
Moderator

The entangled photons are generated through fancy beam-splitting optics. The photons themselves travel the 'slow' speed-of-light way through optical delay lines and fiber. It is only their entangled state which transmits instantaneously.
 

bit_user

Splendid
Ambassador
I'm no physicist, but I've read that quantum communication still doesn't exceed the speed of light. I think the main benefits are the supposed security (yeah, I saw the link but didn't click it), as well as needing neither line of sight nor a physical link.

Being able to send entangled photons on lasers through space or dark fiber solves an important problem of how to keep replenishing the supply of entangled particles, as they eventually become disentangled.
 

Nolonar

Honorable
Dec 17, 2013
107
3
10,685
0
For those who are curious: according to Google, it takes a little over 20 microseconds for light to travel 6 km.
This is 2 million times longer than 10 picoseconds.
 
"one trillionth--that is, one millionth of one millionth--of a second"

No, I'm pretty sure "a million of a million" is a "billionth". When are you people from the USA going to get it right? What you refer to of as a "billion" is "thousands of millions" when it should be "millions of millions".

In any case, very interesting news. I wonder how they are actually measuring the behavior of the protons. In my simple and very limited knowledge of quantum physics, all I know it's not about accurate measurements, but statistical measurements.

Cheers!
 

Lucian Armasu

Contributing Writer
Sep 10, 2014
1,181
3
5,285
0
H Yuka,

You're right, some countries use "billion" to describe "a million millions," but internationally trillion seems to be the preferred term, and it's also what the Canadian researchers themselves used.
 

sinality

Distinguished
Aug 1, 2010
7
0
18,510
0
What the article actually states is the following:
1) We will still be sending photons down a piece of fiber. nothing different than today
2) however we will be able to entangle a single photon with one left behind, send one on to the other side. Once it arrives the data on both photons will the same, entanglement.

Basically this is only serving one purpose, trying to use photon entanglement as a method to encrypt data. Nothing changes are far as latency, capacity, etc.
 

McWhiskey

Reputable
Sep 23, 2015
41
0
4,530
0
Today is the first day I have heard of an alternate naming scheme for numbers. Right up until moments ago I thought the entire world worked the same way.
1,000 - thousand
1,000,000 - million
1,000,000,000 - billion
10^12 - trillion
10^15 - quadrillion
10^18 - quintillion
Meaning 1,000 multiplied 1,000,000 times would equal 1,000,000,000.
So a thousand millions would be a billion.
Sub kilo, mega, giga, tera, penta and so on for metric.
This all fits. Nice and tidy. Logical in my own little brain

But then I learn after a quick Wikipedia search the above is "short scale." And only applies to U.S., English Canada, and modern British. While "long scale" applies to continental Europe, older British, and French Canada.

Long scale confuses me a little. there is something called a "milliard" but other than that every "named" number is in increase of 10^6 instead of 10^3.

Mind blown.
 

husker

Distinguished
Oct 2, 2009
945
16
18,985
0
@Sinality
Yes, this would be a good way to know if there is anyone "sniffing" the data packets being sent, and therefore provide a secure means of communication. The Heisenberg principle would effectively guarantee that that if the packet was sniffed, the entanglement would be compromised, thus alerting the sender and reciever. However, thinking further down the line, I can see them using the concept of alternating the state of a pair of entangled particles to send messages instantaneously over long distances, say, from Mars to Earth or something -- assuming the pair was able able to survive such a trip without losing entanglement. No speed of light limitations as someone else suggested in this thread, the quantum world has it's own rules that defy classical physics. That is the whole point of entanglement and why Einstein called it "spooky action at a distance.
 

bit_user

Splendid
Ambassador
I fail to see why you'd rather say "four thousand million", than "four billion", for instance. I think it's best to use the "short" scale, and then switch to scientific notation for anything beyond.

Anyway, he could've just used scientific notation to clarify the scale of picoseconds.

Then please fix the wikipedia entry:

https://en.wikipedia.org/wiki/Quantum_teleportation
https://en.wikipedia.org/wiki/Faster-than-light#Quantum_mechanics

I wish faster-than-light communications were possible, but the only scheme I've read about that has withstood rigorous analysis is the idea of sending information through a wormhole (which is a bit impractical). I hope I'm wrong, because it seems like it would allow computers to scale without bound.
 

husker

Distinguished
Oct 2, 2009
945
16
18,985
0
@BIT_USER
You and I are both simultaneously correct and incorrect (some quantum humor there). The Wikipedia articles point out that entangled particles affect each other with faster than light timing (as I stated) but this effect, alas, cannot be used to transmit data as we know it, which I did not realize.

From the Wikipedia article on entanglement:
"Recent experiments have measured entangled particles within less than one hundredth of a percent of the travel time of light between them.[7] According to the formalism of quantum theory, the effect of measurement happens instantly.[8][9] It is not possible, however, to use this effect to transmit classical information at faster-than-light speeds[10] (see Faster-than-light § Quantum mechanics)."
 
Very confusing. The entangled particle has to start of as complete, and while it can be separated this is very difficult.

Also, you can't send the entangled half faster than normal transmission speeds. AFTER you do this you can get FTL communication (spooky action at a distance) but you can't transmit actual data. As said somewhere this may be to enable some sort of Quantum encryption but since it's all dumbed down to layman's terms (then further digested for us by people who don't understand the phenomenon) I wouldn't expect to get much out of this.

I am not clear on how Quantum Encryption is supposed to work. I guess I "spin" the particle which causes a "spin" in the entangled half. So then what? The receiving computer tells the sending PC that "yep, it spun"... how does this translate into a MORE secure system? Is this doing something that regular encryption can't do? I just don't see a good explanation.

So far, I've seen little evidence that we're on the verge of massive boosts in transmission or processing speed due to Quantum techniques.
 

bit_user

Splendid
Ambassador
Why not?

As husker said, if you can test for entanglement, then you can know whether there's a man-in-the-midlde attack, on that link. You would only need to do this for some small subset of the photons sent.

I'm not claiming that's what people mean by quantum encryption, though. Honestly, I thought it meant communicating via entanglement, itself.
 
Status
Not open for further replies.

ASK THE COMMUNITY