Quantum prime numbers

Guys: So when, in a few years time(!), we do have quantum computers which can do that prime number factorization thingie via a parallel universe in less time than it takes you to shake a leg, what exactly is going to happen about encryption & privacy?

@JonB said in Quantum prime numbers:
So when, in a few years time(!), we do have quantum computers
I'd likely be dead by the time we have such things, if we have them at all.
which can do that prime number factorization thingie via a parallel universe in less time than it takes you to shake a leg, what exactly is going to happen about encryption & privacy?
It's going to become quantum cryptography?

@kshegunov
Yes, I kind of thought there might a quantum way of adding some more security instead of cracking it. So it'll be calculations going on in your quantum parallel universe against those going on in my quantum parallel universe...!I don't know why you're so sceptical about the arrival of quantum computers. They're only just around the corner! Look, when they first introduced trains they said they couldn't go above 20 miles per hour with women on board as women's bodies could not cope with any higher speeds without blowing apart, and now look where we are... :)

@JonB said in Quantum prime numbers:
I don't know why you're so sceptical about the arrival of quantum computers.
Because I've studied quantum mechanics; as a matter of fact I have to do some calculations regularly for my work. Anyway, I'll crunch some problems for you to think about:
 QM is so entirely different from what you'd expect that if we ever have quantum anything it'd probably be a "module" inside an ordinary computer that's done for one specific task, e.g. crypto. This doesn't mean normal computers are magically going to go away, just that we may amend them.
 There are a multitude of technical problems, most of which boil down to keeping quantum coherence, that aren't easy or straightforward to solve. The research is mostly rudamentary  think the first computers we had  a room of machinery to do something very simplistic.
Now to the more fundamental level:
 QM is a mathematical discipline!
 QM is nonlocal  things happen in all space and time instantly, which is a major drag, and also the reason it's not apparent how it can be integrated with classical fields (think "how to put gravity into it").

@kshegunov
They said we could never fly anything heavier than air, they said we could never go faster than sound.... Quantum computers are here already! They have a onebit one or fourbit one which can factor numbers up to 16 already, it's just a matter of immersing it in an ice bucket and we're good to go commercially....

@JonB said in Quantum prime numbers:
They said we could never fly anything heavier than air, they said we could never go faster than sound....
I have not said we are not going to get anything, I just advised healthy skepticism. Some people used to say we are one step from commercially viable fusion ... 50 years ago ... and we still are 50 years after. The point is  pushing the boundaries of physics and engineering is not easy and takes time & money. Especially if you consider the context  a reactor isn't just some plasma that gets ignited, it's a complicated machinery, which depends on many things being on par with the theory/physics  materials, computers, lasers and what not. We've been doing fusion in a lab for many years, it's easypeasy, making it commercially viable is another kettle of fish altogether.
They have a onebit one or fourbit
That's qbit, which is nothing like an ordinary bit. :)

@kshegunov
So is Qt already planning for its quantum interface?QBit
sounds like a readymade class name for Qt....

This question you have to direct at the head troll; it's way above my paygrade. :D
Yeah, qbit (also qubit) is a nasty thing it's either 0 or 1, or anywhere in between ...

@kshegunov
I can already see the Qt docs for this class & its constructor:QBit(int bit): Creates a new QBit. May or may not initialize it to the bit value specified....
:)

QBit(int bit):
Creates a new QBit. May or may not initialize it to the bit value specified....
See also: Shrödinger's cat, quantum superposition, Physics induced suicide:]

@kshegunov
For the "physics" one, in one of the popular physics books I'm so fond of the author said he believed that no matter what if he were shot, say, then in the universe he lives in he would always come out unharmed [or at least, not dead], somehow. But he said he wasn't brave enough to put his belief to the test.... :)

@JonB the multivers theory is technically not a scientific theory.
A scientific theory is an explanation of an aspect of the natural world that can be repeatedly tested and verified in accordance with the scientific method, using accepted protocols of observation, measurement, and evaluation of results.
Before that you have a hypothesis that is just barely more then a believe ;)

@JonB said in Quantum prime numbers:
But he said he wasn't brave enough to put his belief to the test.
Good idea. Principally, and this is by memory from my school year's thermodynamics, you could put a kettle on a cold plate and wait for it to boil, and it's going to. The problem is that the probability the thermodynamic fluctuation is going to happen is so small, the characteristic time needed for it to occur is immensely (many orders of magnitude) longer than the observed and expected lifetime of the universe. So, while theoretically plausible, it's practically meaningless.
So yes, he could expect the bullet may tunnel through with some probability, he rightfully shouldn't bet his life on it.

@kshegunov
His point was: he would always find "himself" after the shot in one of the universes where all the guns jammed or the bullets missed etc. He could never "find himself" in one of the universes where he died.

@J.Hilk
That may be a little unfair. People work on finding tests for this theory. Some would say that quantum behaviour shows that "parallel universes" actually is the repeatable test/theory/verification/explanation for the behaviour observed.

@kshegunov said in Quantum prime numbers:
This question you have to direct at the head troll; it's way above my paygrade. :D
Yeah, qbit (also qubit) is a nasty thing it's either 0 or 1, or anywhere in between ...I'd love to properly address this but I may, or may not, have a dead cat to deal with.

@JonB said in Quantum prime numbers:
People work on finding tests for this theory.
So? They may be misguided, this doesn't prove or disprove a theory. It's either right or wrong. If it's wrong it either can be corrected or it can't. In the latter case it's just discarded. People worked on the idea that aether is somehow involved with light transmission, this by itself doesn't make it correct.
Some would say that quantum behaviour shows that "parallel universes" actually is the repeatable test/theory/verification/explanation for the behaviour observed.
Some would be wrong. :)

Some would be wrong. :)
Well, I've yet to read a better proposed explanation for quantum phenomena like Young's Slit or Feynman's Path Integral, or even Schroedinger's Cat, so there! Maybe, just maybe, if it walks like a duck and it quacks like a duck then....

Does the explanation matter, though? If numbers add up, theory works and gets confirmed experimentally, then that's good. Humans do no need to intuitively understand it.

@sierdzio
Sorry, I could not agree with you less on this. To me this is like saying that Thor sends thunderbolts rather than physical processes cause them, because the Thor theory "works". I accept that with Bohr's "Shut up and compute" "interpretation" we can get on with the necessary technology, but I believe science is about more than that; and eventually, hopefully, a better understanding will open up new vistas we would not get without it.BTW, I never intimated that our understanding should be intuitive. Much of physics etc. has been about supplying non intuitive explanations, and we have worked at understanding these to our eternal betterment.

@JonB said in Quantum prime numbers:
Maybe, just maybe, if it walks like a duck and it quacks like a duck then....
it could be anything until you measure it. And I know, if those results indicate, that it's a duckrobot you'll say the measuring changed the result
;)

@J.Hilk
Firstly, for asyetunknown reasons, duckrobots will not collapse the wave function, only real fleshandblood ducks will....And secondly, I don't have any "measurement problems" or "measuring changed the result" issues. Nothing got changed, instead I simply discovered my current consciousness happens to be in the universe where the duck quacked left rather than right. An interpretation with which my other infinite selves in parallel universes agree, and another bunch of my infinite selves disagree....
;)

@JonB said in Quantum prime numbers:
duckrobots will not collapse the wave function
And here we have a crux of sorts. The wave function does not collapse per se, and moreover wave functions aren't real, both metaphorically and mathematically. The second one is also the reason you can't ever measure a wave function, nor any of its prescribed properties; it's imaginary (pun intended)!
Well, I've yet to read a better proposed explanation for quantum phenomena like Young's Slit or Feynman's Path Integral, or even Schroedinger's Cat, so there! Maybe, just maybe, if it walks like a duck and it quacks like a duck then ...
Young's experiment shows what you observe, which is not the state of the system but the averaged out of all the photons (electrons, neturons, etc.) passing through the slit. As a matter of fact this has been replicated by using an electron gun that fires single photons and the result is exactly the same (after enough time to acquire enough events). Pretty cool, right?
The path integral is the same idea  getting all the possibilities and averaging them out, that is a single particle does not behave in deterministic fashion, it's the averaged you can observe and measure.
And the similarly with Schrödinger's cat  until you measure something the state of the system is undetermined, that is to say it exists in a superposition of its pure states. When you measure it you break the coherence as the system is no longer conservative and the state collapses in one of the two possible pure states. It's an illustration more than anything.
The uncertainty principle is actually nothing QM specific. If you account that the momentum is the Fourier image of the coordinate(s), you're probably going to realize that there's an uncertainty principle in good ol' electronics:
Take a signal and do itss Fourier transform, what's the spectrum at a specific time of that signal? Nobody can say. The spectrum of the signal pertains to the whole time, not to a specific point. One point of the spectrum relates to the frequency you'd observe if you had an infinitely long signal. So it's not hard to realize that dirac's delta (an infintely short impulse) generates all frequencies equally and vice versa  a dirac's delta as a spectrum just means a constant signal.

@JonB said in Quantum prime numbers:
@sierdzio
Sorry, I could not agree with you less on this. To me this is like saying that Thor sends thunderbolts rather than physical processes cause them, because the Thor theory "works".That's not what I meant. Ideas are tested and they work, this is different than saying "Thor did it". It's rather "Thor did it, and here's the proof".
What I mean was rather to say that the Universe is under no obligation to make sense to us. Thus, I view these quantumrelated ideas similar to wave vs. particle  particles are both waves and particles, and it does not make sense, but that's just how nature works. In "reality" it only does not make sense to us, because we lack a good analogy for it in our "big" world. It's us who lack the proper dictionary.
And in any case, an "explanation" is always oversimplified. "Lies to children", as Ian Stewart says. They are just tools to get us to some better understanding of the phenomena, but they are not true and not right, for the most part. The equations are.
... eh I have a feeling I'm not explaining this properly and you'll misunderstand me again :D Well, no problem.
BTW, I never intimated that our understanding should be intuitive. Much of physics etc. has been about supplying non intuitive explanations, and we have worked at understanding these to our eternal betterment.
Yep. I think we agree here, we just didn't understand each other ;)

I thought Google had a 72 bit quantum computer? As in 72 individual bits they could manipulate.
I have to imagine that if there is a 4th dimensional (or higher) being that their view of the universe is quite different than ours. So when I hear about wave vs particle inconsistencies I think that our current understanding of how the universe is structured might be based on assumptions we don't even see as assumptions. From our viewpoint we see the world as solid. However, to gamma the world is swiss cheese. Is our viewpoint just skewed?

I thought Google had a 72 bit quantum computer? As in 72 individual bits they could manipulate.
I've always marvelled at how fast my Google searches are, now I know!