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> It's hard to say. Industry experts like Scott Aaronson have gone back on forth with regards to whether or not it's 1) truly a quantum computer and 2) capable of real improvements over classical computers for anything nontrivial. Point #2 is perhaps more important for practical purposes.

I down-voted this. I have only a layman's understanding but from what I have read particularly #2 is demonstratively false, D-Wave has not achieved any improvements over classical computers for anything (including it's very own domain problem, which Alex Selby's classical algorithm outperforms D-Wave on). [0][1]

[0] http://www.scottaaronson.com/blog/?p=2555#comment-974407

[1] http://www.scottaaronson.com/blog/?p=1400

I should clarify - I agree with you in that #2 is demonstrably false. But Aaronson has gone back and forth on his skepticism for D-Wave.[1] He is now rightfully back in the skeptical camp, however.

My main point was that acknowledged experts have gone back and forth on this and there have been conflicting publications about D-Wave's computers. Now that I review the research again, it looks like it's been experimentally shown to have legitimate entanglement implemented in the computers, but the consensus is indeed that there is no quantum speed up or improvement or classical computers.

Thanks for the reply though, I've edited the original comment.

[1]: http://www.scottaaronson.com/blog/?p=639

The parent said capable of real improvements over classical computers, not whether it has achieved it. Of course some hold the opinion that it's at least capable of it (Google, NASA, D-Wave employees) but the jury seems to remain out.

No point to refer to "industry experts". Either data shows speedup, or it doesn't. Things will become clear after they release the next version [0]. If there's x1000 speedup, as claimed, it's a real deal, no matter if it's "really quantum" or otherwise.

[0] http://www.dwavesys.com/media-coverage/techrepublic-quantum-...

>If there's x1000 speedup, as claimed, it's a real deal, no matter if it's "really quantum" or otherwise.

Except not, because constant time speedup isn't interesting, 1000x classical computers will get you the same effect probably for less $ than d-wave. The entire point is that a genuine quantum computer should achieve an asymptotic speed-up not a constant factor one, which no one really cares about.

> The technology is apparently impressive enough that Google, NASA and Lockheed Martin have partnered with D-Wave to test its capabilities

As someone who has actually worked in the research divisions of NASA and Lockheed, I wouldn't assign this form of social proof any value. There is absolutely nothing to infer from fact that NASA and Lockheed bought prototypes. I don't have personal experience with Google, but it is not unlikely that the same effects are at work.

Scott Aaronson's posts on D-Wave are worth reading in full, including the discussion in the comments. He's a brilliant guy and his intellectual honesty is commendable. In other words, he's willing (and excited) to be proved wrong.

> That said, I mostly follow quantum cryptography,

Which is also a field full of bullshit and nonsensical claims, and it still has to prove that it provides a solution for any real problem.

If you're interested, the Quantum Key Distribution [0] sub-field has already likely bore fruit that is a "ready in the medium-term" useful solution to a real problem. It's probably already deployed somewhere in the national security/defense space.

[0] https://en.wikipedia.org/wiki/Quantum_key_distribution

DJB is still skeptical of Quantum Key Distribution.

https://sidechannels.cr.yp.to/qkd/holographic-20160326.pdf

Which problem exactly does QKD solve? (It is used by some banks afaik, but that it's used doesn't mean it solves any problem - it just means someone bought the marketing claims from ID Quantique and co)

A quick response (so forgive the brevity): Let's say worst case, that a quantum computer does not currently exist, but its basic logical operation has been fleshed out to a reasonable extent. Now, what if a practical implementation shows up in the 5-10 yr timeline. The issue is that some quantum computers could, in theory, pose a real threat to many currently used classical encryption systems. QKD + one time pad could provide, in theory if not already also in practice, a reasonable stand-in solution to counter this perceived threat.

This is not true. Quantum cryptography is frequently conflated with concepts that are not possible and don't make sense, but quantum key distribution is a legitimate area of research. In fact, it has already been experimentally implemented (Los Alamos, UCambridge, UGeneva, etc).

It might not be mature enough yet for widespread adoption, and it doesn't revolutionize all parts of a cryprosystem, but it is definitely progress in the narrower problems of key distribution and perfect forward secrecy for one-time pads.

Unless I'm misunderstanding you and what you mean is that the field has many people opportunistically using the term for marketing things that are not really quantum cryptography; if that's the case, I agree with you.

> but quantum key distribution is a legitimate area of research

If you used that with the meaning "we don't know how to do anything useful with it, but it is worth looking because there may be some use", I would grant you this point. But:

> In fact, it has already been experimentally implemented (Los Alamos, UCambridge, UGeneva, etc).

No. The existing protocol for quantum key distribution is insecure bullshit.

Maybe it's a legitimate area of research. But I hear frequently obvious bullshit claims from these researchers, like that they want to build a quantum internet.

And I don't see how quantum key distribution solves any problem. It's kinda circular - it requires an existing authenticated channel to work, which needs math-based crypto. At the same time the whole field is built on the claim that they're needed because they don't trust math-based crypto.

"It might not be mature enough yet for widespread adoption, and it doesn't revolutionize all parts of a cryprosystem, but it is definitely progress in the narrower problems of key distribution and perfect forward secrecy for one-time pads"

I'm not sure. The best minds I've talked to in high-assurance security don't believe it. One, Clive Robinson on Schneier's blog, predicted we'd see classical attacks on it. Something like that happened. I pointed out there would still be software, endpoints, interception, subversion, etc for bypass whereas the tech itself was little understood versus effects of regular electronics. Tried and true beats novel and new if it's high-security I always say.

No, these devices are not trustworthy or even necessary that I can tell. High-assurance key exchange is a solved problem if the organization is the simpler, hierarchical designs likely to use QKD. Many solutions available with the most reliable being a courier and key-handling hardware you can trust that only has part of the secret + another transmitted over various medium with it all using several layers of symmetric to work (eg my polymorphic schemes). All on dedicated, low-TCB devices.

I don't know what QKD costs today but I bet it's still cheaper to courier the pre-shared keys and use tamper-resistant hardware. Do you have numbers on it in terms of amount of keys negotiated over time and at what cost for hardware w/ HA setup?