Does Quantum Computing Actually Work?

[Bloo Loo]

I wonder if the Quantum computing is subject to observer Bias... as in the quantum state has to be effected by the act of observation, for example, the World as observed isnt gone one second, here the next, we observe it in constant state all the time.

[Gigantic Purple Slug]

I wonder if the Quantum computing is subject to observer Bias... as in the quantum state has to be effected by the act of observation, for example, the World as observed isnt gone one second, here the next, we observe it in constant state all the time.

Well you're getting deep into the mysteries of qm and how it should be interpreted there.

For me I don't have time for the philosophical musings - I see the point of them but the labour involved in getting to a stage where you can meaningfully debate them is too much.

My approach is that if it walks like a duck and quacks like a duck then it most probably is a duck. I haven't seen this happen in public yet, although I suspect it has (some powerful organisations have significant interests in obtaining a practically useful quantum computer).

[knock out johnny]

I wonder if the Quantum computing is subject to observer Bias... as in the quantum state has to be effected by the act of observation, for example, the World as observed isnt gone one second, here the next, we observe it in constant state all the time.

What happens when you turn it off and on again?

[dgul]

What happens when you turn it off and on again?

You just can't do that on a quantum computer. The computer is simultaneously on, off and all possible states in between, at all times.

The computer support unions are up in arms against it, apparently, as they can't use their normal methods to do IT support. But the unions have not yet realised that QCs are quite good for them, as when they're not actually being observed (eg, while having a nice cup of tea) they cease to exist (or, at least, appear to cease to exist) and thus can't break down (or, at least, appear to not be able to break down).

[debtlessmanc]

I googled this and you get myriad pages of what quantum computers are supposed to do, Qubits being the quantum bit on which we can encode much more info, apparently

I read that whatever algorythm you put in, it produces all anwers at once.good for decryption perhaps.

My problem is, does this actually happen, and how do you know what the right answer is?

Incredibly difficult problem- the real interest is from the military as you could crack every public key code system straight away

My guess is that is it is 30 years away and then will be too expensive for mass production for another 20. But as usual some smart ass might find a way to do it sooner.

As to what it can do- basically it can access an infinitely large set of solutions to a problem. So it could solve chess of factorise any number- if you have a enough qbits to encode the number

[Bloo Loo]

Incredibly difficult problem- the real interest is from the military as you could crack every public key code system straight away

My guess is that is it is 30 years away and then will be too expensive for mass production for another 20. But as usual some smart ass might find a way to do it sooner.

As to what it can do- basically it can access an infinitely large set of solutions to a problem. So it could solve chess of factorise any number- if you have a enough qbits to encode the number

I see it could crack all the possible codes, (at least that is the main app it seems to do well wherever you read), but the problem remains, it has given all possible answers, how do you output the one that is correct instantly...?

[happy_renting]

I see it could crack all the possible codes, (at least that is the main app it seems to do well wherever you read), but the problem remains, it has given all possible answers, how do you output the one that is correct instantly...?

Ha! You obviously have no grasp of how Quantum computing works!

Nor do I.

[Scunnered]

I see it could crack all the possible codes, (at least that is the main app it seems to do well wherever you read), but the problem remains, it has given all possible answers, how do you output the one that is correct instantly...?

Because there's only one correct answer. The way public-key cryptography works is that you take two large (dozens/hundreds of digits) prime numbers p and q, and multiply them together to get a number k which is your public key. You can tell everyone what that is, and they can use it to encode a message that they send to you, but you can only decode it if you know p and q (your private key, which you don't tell anyone). So if someone can look at k and work out what p and q are, then they can decode any messages sent to you. The problem is that it seems (although no-one's managed to prove this one way or the other, at least as far as the public knows) that you can't do much better on a classical computer than to try all the possibilities for p: 2,3,5,7,11,13,17,... and see which one divides k. To do this for the kind of numbers used in current public-key systems would take many times the lifetime of the universe, so it seems to be pretty safe. The thing is that a quantum computer can more or less try all of the possibilities at once, so it can split k into p and q very quickly.

I think.

[happy_renting]

Because there's only one correct answer. The way public-key cryptography works is that you take two large (dozens/hundreds of digits) prime numbers p and q, and multiply them together to get a number k which is your public key. You can tell everyone what that is, and they can use it to encode a message that they send to you, but you can only decode it if you know p and q (your private key, which you don't tell anyone). So if someone can look at k and work out what p and q are, then they can decode any messages sent to you. The problem is that it seems (although no-one's managed to prove this one way or the other, at least as far as the public knows) that you can't do much better on a classical computer than to try all the possibilities for p: 2,3,5,7,11,13,17,... and see which one divides k. To do this for the kind of numbers used in current public-key systems would take many times the lifetime of the universe, so it seems to be pretty safe. The thing is that a quantum computer can more or less try all of the possibilities at once, so it can split k into p and q very quickly.

I think.

So good security is a matter of minding your P's and Q's.

[The XYY Man]

What happens when you turn it off and on again?

That talentless twät Phil Collins gets some more friggin' royalties..!

XYY

[knock out johnny]

Because there's only one correct answer. The way public-key cryptography works is that you take two large (dozens/hundreds of digits) prime numbers p and q, and multiply them together to get a number k which is your public key. You can tell everyone what that is, and they can use it to encode a message that they send to you, but you can only decode it if you know p and q (your private key, which you don't tell anyone). So if someone can look at k and work out what p and q are, then they can decode any messages sent to you. The problem is that it seems (although no-one's managed to prove this one way or the other, at least as far as the public knows) that you can't do much better on a classical computer than to try all the possibilities for p: 2,3,5,7,11,13,17,... and see which one divides k. To do this for the kind of numbers used in current public-key systems would take many times the lifetime of the universe, so it seems to be pretty safe. The thing is that a quantum computer can more or less try all of the possibilities at once, so it can split k into p and q very quickly.

I think.

So what happens when my password is my pet dog? Which it is!

[Bloo Loo]

So what happens when my password is my pet dog? Which it is!

confound them NSA bods by adding capitals in odd places.

[Scunnered]

So what happens when my password is my pet dog? Which it is!

Schrödinger's dog...

[knock out johnny]

Schrödinger's dog...

You only know if it's taken a sh!t in the hallway once you've opened the front door and stepped in it

[Gigantic Purple Slug]

Has Dr Evil got a Quantum computer yet?

In fact, who does claim to have them? Do the Russkis and Chinese. Has the DM run any stories yet on the possibilities if ISIS had one?

If you look at a lot of this sort of stuff it is invented by various agencies often before it is in the public domain, take RSA encryption for example :

https://en.wikipedia.org/wiki/RSA_(cryptosystem)

There would be two reasons why you wouldn't want the world to know. First would be that people would then know RSA is not safe, or at least not as safe as they thought it was. Second is that if you knew someone had a quantum computer and how many qbits it had you could beef up the length of your encryption key to make decoding impractical still.

There is plenty of precident for decoding computer technology to be kept secret. You can read about Bletchley Park and the enigma machines for example.

I doubt though there is a QC in a tora bora style cave complex with a slidey pole down to a stable of horses ready for the operators to make a quick getaway.

[Bloo Loo]

[happy_renting]

Schrödinger's dog...

You can only tell if it is alive or dead by opening the box.

Or by the smell.

[Bloo Loo]

You can only tell if it is alive or dead by opening the box.

Or by the smell.

bit like Schroedingers Fat Cats....they are dead but kept alive by quantum bailouts