Dirty carbon nanotubes offer telcos chance at secure quantum comms

Single-photon emitters aren't a new thing in physics labs, but they usually require liquid-helium-chilled freezers. America's Los Alamos National Laboratories (LANL) reckons it's cracked a difficult double: a telecom-frequency single photon emitter that works at room temperature. This has potential because the two key …

[Charles 9]

The article seems incomplete. After all, what's to stop Eve emitting a new proton to Bob to replace the one she read?

[Anonymous Coward]

You mean other than the fact he's expecting a photon, not a proton?

[Dave 126]

To explain it reasonably well requires more room than the article can give it. Try here:

http://gva.noekeon.org/QCandSKD/QCandSKD-introduction.html

[Doctor Syntax]

"To explain it reasonably well requires more room than the article can give it."

Dammit. The margin wasn't big enough.

[Doctor Syntax]

"After all, what's to stop Eve emitting a new proton to Bob to replace the one she read?"

It seems to be a bit more complicated than that but I'm still not clear why, by intercepting all the channels Alice and Bob use rather than simply eavesdropping, a MITM attack becomes impossible.

[John Smith 19]

ARyl --> Contains a benzene ring

Very impressive.

Single unit (photon or electron) X Room temperature operation --> Very hard to do.

The question then becomes can you do a single photon detector at room temp and how far can you transmit that photon in ordinary FO cable?

[Dave 126]

Re: ARyl --> Contains a benzene ring

Presumably the range of the photon in FO cable doesn't depend on how that photon was generated.

[John Smith 19]

"Presumably the range of the photon in FO cable doesn't depend on how..photon was generated."

It doesn't, but normal light pulses in conventional systems (despite the Gbs data rates) are made up of millions (billions?) of photons.

Obviously you can then afford to lose quite a few before their loss is noticed.

[Pascal Monett]

"aryl sp3 is an organic molecule [..] bound to the surface of the nanotube"

And that's how the Borg got started . . .

[Alan Brown]

reason for the wavelengths

nothing to do with the amplifers(*) and everything to do with the windows of tranparency in optical fibre

(*) The amplifiers are (of course) created to operate at the optimal frequencies, not the other way around.

[Anonymous Coward]

Dirty Carbon is the name of my favourite stripper.

[Rocketist]

The di-- what?

“The diazonium reaction chemistry allowed a controllable introduction of benzene-based defects with reduced sensitivity to natural fluctuations in the surrounding environment.”

Sounds a bit like "the dilithium reaction chemistry allowed a controllable introduction of defects which results in an field inversion in the surrounding..."

Where's a Star Trek icon when you need one?

[Kernel]

What happens when you amplify this photon

An optical amplifier does its magic by emitting a second, identical, photon when an incoming photon hits an atom of the doping material which has an electron at a higher than normal energy level, without destroying the original photon - these two then go on to cause other photons to be similarly emitted, thus ensuring that the egress signal is at a higher level than the ingress.

I might be missing something here, but it seems to me that once the single photon has been through an amplifier there will now be considerably more than one of them, giving Eve plenty of opportunity to listen in without Bob noticing anything wrong.

On the other hand, the little I've read about soliton transmission systems suggests that perhaps a single photon traveling alone may have a range of thousands of km without amplification, so maybe this is the answer.

[Charles 9]

Re: What happens when you amplify this photon

Those optical amplifiers IIRC also don't work at the quantum level. Meaning the copy photons emitted don't carry the same quantum properties as the original, spoiling your effort as it's those quantum properties that are the key to reading the message, and as best as I can tell, there is (1) no way to detect those quantum properties without absorbing the photon first, and (2) you can only detect one set of properties or another, meaning you have a 50/50 chance of getting nothing at all unless you already know the way it's coming in (a shared secret).

[Kernel]

Re: What happens when you amplify this photon

Fair enough, that explanation works for me. Thanks.