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A rudimentary quantum network link between Dutch cities

tudelft.nl

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Re: A rudimentary quantum network link between Dutch cities

#21

Post by metropolbadger »

ziofill wrote: post #3

I've worked in quantum nonlinear optics during my first postdoc 12 years ago, and back then we could only dream of the efficiency of frequency conversions that are used here. So many advances in just a decade, and most of them don't even make the news.

All those incremental changes is what made my research work indeed. As we described in the paper, the margin we had on amount of signal (dependent also on the conversion efficiency!) was small, so every % of loss anywhere in this chain of photon from emission to detection mattered.

Re: A rudimentary quantum network link between Dutch cities

#22

Post by ko27 »

fi358 wrote: post #15
knoke wrote: post #14

Earlier quoted context omitted.

As far as In understand it (not very much) you can listen in on the transmitted keys, but the interaction can be statistically(!) measured and suspicious bits can me omitted (the wiki is quite comprehensible: https://en.wikipedia.org/wiki/Quantum_key_distribution?wprov... ). There are different protocols, some more and some less quantum and most rely on classical, encrypted channels and trusted nodes in addition to t…

As far as I know, they still need classical encryption methods (with something like shared secret key or public key for authentication) to detect active man in the middle attacks where the attacker prevents the parties connecting to each other and then pretending to both parties to be the other party by creating his own "messages" as if they came from the other party. Or at least to have some kind of additional trust…

You don't need "classical encryption" for quantum key distribution. With QKD you can provably detect if a MITM attack happened. With classical methods you can never be 100% sure, although how much of that matters in practice is another question.

Re: A rudimentary quantum network link between Dutch cities

#23

Post by Havoc »

metropolbadger wrote: post #20

Hi all! I'm one of the co-authors. Honestly it's a dream to end up on HN with my research. As mentioned in the video we made, it has been a long road (6-7 years) to achieve this absolute moonshot of a project. I think we'll look back on this demonstration as the first experiment that truly made a distributed and real-world deployed quantum network. Not only did we use a (quantum) hardware platform capable of quantum…

It says over fiber. I assume that has to be a straight shot point to point non-routed? Or could this deal with repeaters and routers etc

Re: A rudimentary quantum network link between Dutch cities

#24

Post by bawolff »

ccppurcell wrote: post #17
bawolff wrote: post #6

What is actually the usecase for "quantum internet"? Like at most i hear about quantum key distribution, but quite frankly the classical equivalents to that are just as good if not better, so what is the actual benefit?

I don't know about use case but in various distributed computing models there are problems that are provably easier for quantum computers. Unlike the classical setting where the best we have is factoring where we don't know an efficient deterministic algorithm and various problems which experimentally seem to be faster for QC (and those results often don't last long as we get better at simulating quantum algorithms c…

I agree that quantum computers are useful. Its quantum internet that seems pointless.

As far as i am aware, none of the problems faster on a QC are helped in anyway by quantum internet.

Re: A rudimentary quantum network link between Dutch cities

#25

Post by bawolff »

p_l wrote: post #19
bawolff wrote: post #6

What is actually the usecase for "quantum internet"? Like at most i hear about quantum key distribution, but quite frankly the classical equivalents to that are just as good if not better, so what is the actual benefit?

Safer mechanisms of distributing and establishing "root" keys for identify verification (so you can then use them easier with normal D-H on normal internet) is one use case I recall from 1990s. But few years ago I heard of some other interesting uses where quantum properties were used to essentially enable DWDM-like virtual circuit routing with higher capacity - though I would have to look again if it went anywhere o…

> Safer mechanisms of distributing and establishing "root" keys for identify verification

Except it doesn't solve the mitm problem, so its not really safer.

Re: A rudimentary quantum network link between Dutch cities

#26

Post by bawolff »

ko27 wrote: post #22
fi358 wrote: post #15

Earlier quoted context omitted.

As far as I know, they still need classical encryption methods (with something like shared secret key or public key for authentication) to detect active man in the middle attacks where the attacker prevents the parties connecting to each other and then pretending to both parties to be the other party by creating his own "messages" as if they came from the other party. Or at least to have some kind of additional trust…

You don't need "classical encryption" for quantum key distribution. With QKD you can provably detect if a MITM attack happened. With classical methods you can never be 100% sure, although how much of that matters in practice is another question.

> You don't need "classical encryption" for quantum key distribution. With QKD you can provably detect if a MITM attack happened.

This is incorrect. QKD can detect passive mitm only. It cannot detect an active mitm.

Which is the main reason its overhyped, since as cool as QKD is, you still need active mitm prevention, so you have to rely on classical crypto anyways.

Re: A rudimentary quantum network link between Dutch cities

#27

Post by fulladder »

bawolff wrote: post #16
portaouflop wrote: post #11

Earlier quoted context omitted.

There is no obvious benefit yet, they are just researching for the sake of it. I think over time they will discover a benefit but the hype is obviously not warranted.

I guess, but benefits should be more theoretical. Like i don't think building one will give any insight into ideas for protocols. We already understand how it would work in theory and have for a long time.

Just because their work is not of immediate practical importance does not mean it lacks value.

Re: A rudimentary quantum network link between Dutch cities

#29

Post by andai »

metropolbadger wrote: post #20

Hi all! I'm one of the co-authors. Honestly it's a dream to end up on HN with my research. As mentioned in the video we made, it has been a long road (6-7 years) to achieve this absolute moonshot of a project. I think we'll look back on this demonstration as the first experiment that truly made a distributed and real-world deployed quantum network. Not only did we use a (quantum) hardware platform capable of quantum…

Layman here! I have no idea what's going on but I have many questions!

- Are the photons themselves carrying quantum information?

- Does the photon link result in entangled particles in Delft and Den Haag?

- Can these entangled particles be used for communication without the optical link?

Also, I tried looking this stuff up and ran into something about quantum "repeaters" and a plans for a whole quantum network. Is this research part of working towards that? How far are we now, and what steps are still missing? Thanks!

Edit: Looks like you guys built a multi-node quantum network 2 years ago! I will have to do some more reading.

Re: A rudimentary quantum network link between Dutch cities

#30

Post by pclmulqdq »

Havoc wrote: post #23
metropolbadger wrote: post #20

Hi all! I'm one of the co-authors. Honestly it's a dream to end up on HN with my research. As mentioned in the video we made, it has been a long road (6-7 years) to achieve this absolute moonshot of a project. I think we'll look back on this demonstration as the first experiment that truly made a distributed and real-world deployed quantum network. Not only did we use a (quantum) hardware platform capable of quantum…

It says over fiber. I assume that has to be a straight shot point to point non-routed? Or could this deal with repeaters and routers etc

All of the quantum networking stuff is point-to-point. It's not clear to me whether fiber amplifiers are even allowed on these links.
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