Quantum Physics

whats a quantum computer?

One way to look at it is ordinary computers do everything in 0 and 1 known as binary, so to represent '9' in binary you have to write 1x(2x2x2) + 0x(2x2) + 0x(2) + 1 => 1001, or 4 bits of information.  Each bit is a placeholder of 1 or 0.

A quantum computer is continuous (I know it's odd saying a quantum computer is continuous while a classical computer is quantized) so it can write 9 as easily as it can write 1, so calculations become much faster.

But then the quantum subtlety comes in.  A quantum computer is actually keeping all these 4 bits of information found in the ordinary computer, but it allows you to see them all at once, hence the speed up.  But because it's quantum, it actually doesn't allow  you to see the order, it just lets you know there's 2 placeholders that have 1 in them, without telling you where.  So you could have 0011 = 3, or 0101 = 5, or 1100 = 12.....as well as 1001 = 9.  The trick is how to use lower quality information that gets to you faster.  Maybe you have to see it divides evenly by 2; is it less than 10, etc.  Eventually you'll get there.

Some examples are given in https://plus.maths.org/content/how-does-quantum-commuting-work

You have to do more work to get your answer, but since the work goes so much faster the end result is faster.

As to how to build the damn thing, there are several ways. One is you'll need to make an array of "quantum boxes", which can be no more than holes in metal that could hold electrons, or photons, what have you.  In a classical computer if they have or don't have a particle it's a 0 or 1; in a quantum computer they have to somehow have communicated with each other so that it's a superposed state, and what's going on in one is related to the others.  One way to do this is to shoot them through a beam splitter so that if a particle goes one way it can't have gone the other.  Reading one box tells you what's in the other.  The trick then is to program your beam splitter to reflect your problem.   Maybe it's a 50/50 beam splitter, or a 30/70 reflecting the chances of going one way or another.

In reality people use electrons that can have "spin up" or "spin down", like little magnets oriented pointing north or south. But that's getting tricker to visualize if you're not used to it.

yikes! I understood about 5% of that, but thanks anyway.

{{ Same Figg, but with any luck you understood a differnt 5% than me and so between us we can understand 10% of it!! }}

What, you think I understood any of it?

I neither understand nor fail to understand most of it...
or at least some of it...
I think...
 

I understood the words ' its faster' and that's about it really.

Dave is in a state of quantum superposition.

David H wrote:I neither understand nor fail to understand most of it...
or at least some of it...
I think...
 

To think that even around 1900 it was still possible to debate if atoms existed (Einstein settle it with his calculations of Brownian motion), and here we have our first moving picture at atoms moving around and even binding.  rhenium atoms in a carbon nano tube.



I'd post the journal link but I don't think reading it is all that enlightening.

Hey David, saw this and read a lot of words. Care to translate into laymen terms what this means?

Heisenberg limit gets a meaningful update

Arg, the Bayesian approach is only different from the frequentist approach if you have incomplete information but new evidence is coming in. Unless they specify how the available information is being limited I don't see the advantage. This has shades of Einstein's real versus Bohr's experimentally realized universe. I may come back and comment in full later, no time now.

the kid at the beginning is brilliant. I'll see about the rest.

The students they got are so totally NYC: racially indeterminate and smart.

I like that she keeps pulling in (young) women to talk to. I always preferred female students when teaching physics. They're less distracted by male intellectual BS. (I know I'll get some flack from this).

I think mens brains are easily distracted Ive seen so many young boys at school, including my son, who drifted off into another world & yet the girls at least showed a bit of interest

this will be interesting:

https://www.smithsonianmag.com/science-nature/new-experiment-hopes-solve-quantum-mechanics-biggest-mystery-180974132/

Sorry Nagual, your earlier question about Bayesian uncertainty principle gets so far into abstractions that I just haven't had time to clarify it.

halfwise wrote:The students they got are so totally NYC: racially indeterminate and smart.

I like that she keeps pulling in (young) women to talk to. I always preferred female students when teaching physics.  They're less distracted by male intellectual BS.  (I know I'll get some flack from this).

I should add that this difference vanishes by mid career college. But in high school, yeah, it's girl power all the way. The funny thing is, the boys think they're so smart in high school, and that's their downfall.

Something doesn't add up. there'd be much more dark matter than ordinary matter, so why don't we see it routinely on earth? Granted a hexaquark is a sort of super neutron so doesn't interact much with EM waves, but one would think they'd bind in nuclei via the strong force and so they'd be noticed.

{{ I'm just going to nod in the assumption the words you used Halfy make sense to someone and in the hopes I dont seem as stupidly drunk as I am! }}

{{ Right where are the brainy people?!!

Turns out Ive been pondering a mathmatical quandary all my life without really knowing it was one.
You see when I was a kid it was the days of the record player still, lp's especially are the point as when a kid I found record players lots of fun for things other than music, such as sitting action figures on the record as it spun.
And it was doing this I hit a bit of a puzzler- if I put an action figure near the edge, and assuming it didnt spin right off, and then put another action figure near the middle of the record and spun the record at one of its two set speeds, they both go round 1 revolution at same time- which even to my kid brain didnt make sense, as surely the one near the middle is travelling a lot less further than the one on the edge, so how can they, whilst travelling at same speed butover different distances, go round exactly once at same time?

Anyhow this has bubbled away at back of my head for about 40 years now as one of lifes unanswered mysteries.
Today I stumbled on this youtube vid giving an explanation of why this occurs-



So if it explains it why do I need the brainfolk? To explain the explination!!!! There are infiintie numbers between numbers and that somehow means my action figures, despite travelling different distances do so in the same amount of time travelling at same speed? What? How does that even help?!! I hate maths, it might be right but it doesnt make a blind bit of human sense. }}}

azriel wrote:I think mens brains are easily distracted  Ive seen so many young boys at school, including my son, who drifted off into another world & yet the girls at least showed a bit of interest

Of course, while the girls were studying physics, I was looking at the girls thinking of chemistry....

Pettytyrant101 wrote:{{ Right where are the brainy people?!!

Turns out Ive been pondering a mathmatical quandary all my life without really knowing it was one.
You see when I was a kid it was the days of the record player still, lp's especially are the point as when a kid I found record players lots of fun for things other than music, such as sitting action figures on the record as it spun.
And it was doing this I hit a bit of a puzzler- if I put an action figure near the edge, and assuming it didnt spin right off, and then put another action figure near the middle of the record and spun the record at one of its two set speeds, they both go round 1 revolution at same time- which even to my kid brain didnt make sense, as surely the one near the middle is travelling a lot less further than the one on the edge, so how can they, whilst travelling at same speed butover different distances, go round exactly once at same time?

Anyhow this has bubbled away at back of my head for about 40 years now as one of lifes unanswered mysteries.
Today I stumbled on this youtube vid giving an explanation of why this occurs-



So if it explains it why do I need the brainfolk? To explain the explination!!!! There are infiintie numbers between numbers and that somehow means my action figures, despite travelling different distances do so in the same amount of time travelling at same speed? What? How does that even help?!!   I hate maths, it might be right but it doesnt make a blind bit of human sense.   }}}

I’ll get to your post once I’ve found the brainy people. Ummmm... do we get a clue about where to start looking...as that would seem only fair to me...