Earlier quoted context omitted.
They don’t need to hack the network, just turn some people or beat them with rubber hoses.
Obligatory xkcd https://xkcd.com/538/
Cambridge launches UK’s first quantum network
11–20 of 33 posts
Re: Cambridge launches UK’s first quantum network
#12Re: Cambridge launches UK’s first quantum network
#13Re: Cambridge launches UK’s first quantum network
#14Earlier quoted context omitted.
Yes. Can these be used in cases where traditional radio systems can't be used? Like deeply submerged submarines?
Having a bunch of entangled particles doesn't actually let you communicate. You still need to exchange particles with your interlocutor. If you can't communicate classically, you can't communicate with quantum states either- this is the no-communication theorem. Quantum mechanics allows for superdense coding, where you get a bit more than one bit per particle, but it's probably not really helpful.
But you can then twiddle with these photons after exchange right?
Use them to communicate after?
Otherwise what's the point?
Re: Cambridge launches UK’s first quantum network
#15quantum computers arent real though are they
Re: Cambridge launches UK’s first quantum network
#16Earlier quoted context omitted.
Having a bunch of entangled particles doesn't actually let you communicate. You still need to exchange particles with your interlocutor. If you can't communicate classically, you can't communicate with quantum states either- this is the no-communication theorem. Quantum mechanics allows for superdense coding, where you get a bit more than one bit per particle, but it's probably not really helpful.
But you can then twiddle with these photons after exchange right? Use them to communicate after? Otherwise what's the point?
[deleted]
Re: Cambridge launches UK’s first quantum network
#17I wonder how intelligence services around the world are planning to combat the rise of these allegedly "unhackable" communication networks.
Here's a start (hint: they're not "unhackable" nor are they actually "guaranteed by the laws of physics")
Re: Cambridge launches UK’s first quantum network
#18I wonder how intelligence services around the world are planning to combat the rise of these allegedly "unhackable" communication networks.
> allegedly "unhackable" communication networks
they are unhackable using classical methods. So the hacks would be QM based as well (so DefCon will be like QM physicists symposium). Like something along the lines of entangling with (yet not measuring) the signal and performing "shadow" ("counterfactual quantum communication") read of a that signal (entanglement transitivity/swapping, especially if the read/measurement is done after Alice&Bob had already got satisfied with the integrity of the signal as there are also interesting possibilities with that "entanglement in the future affecting the past". Or like this QM analog of NSA Google fiber splitter https://www.extremetech.com/extreme/156673-the-first-quantum... : the photon 4 would be injected back into the channel and Alice and Bob would never know the difference [between the pair 1,4 and the original pair 1,2] while the photon 3 would go into Eve's pocket ).
Re: Cambridge launches UK’s first quantum network
#19Earlier quoted context omitted.
Having a bunch of entangled particles doesn't actually let you communicate. You still need to exchange particles with your interlocutor. If you can't communicate classically, you can't communicate with quantum states either- this is the no-communication theorem. Quantum mechanics allows for superdense coding, where you get a bit more than one bit per particle, but it's probably not really helpful.
But you can then twiddle with these photons after exchange right? Use them to communicate after? Otherwise what's the point?
> Having a bunch of entangled particles doesn't actually let you communicate. [...] this is the no-communication theorem.
Re: Cambridge launches UK’s first quantum network
#20Can someone with more knowledge on this topic speak to whether this is likely to take off, or is it just a research toy?
It's not likely to take off.
Do you want pre-shared secrets and the expense of a quantum network to, in theory, have infinite security (in theory!), or are you okay with tried and tested RSA which gives you >1000000000 years security at a much cheaper cost, that actually works in practice?