Amazing!!!!

"That is at the heart of quantum interrogation schemes, and to my mind, quantum mechanics doesn't get any more mysterious than this."

Makes me appreciate my favorite quantum physics quote all over again:

"If one has to stick to this damned quantum jumping, then I regret ever having been involved in this thing."

Erwin Schrödinger

But it also reminds me that someone (forget who) prophesied that it would take at least a couple generations to take good advantage of quantum physics because earlier scientists had preconceived concepts of reality that inhibited them.

You know, the intern working while sweeping up the lab, who figures out exactly how improbable the device would be, and it suddenly appears?

So... these people have managed to run calculations on a quantum computer they haven't even turned ON?

...I understand enough about quantum mechanics to see how that makes sense quantum mechanically, but it still blows my mind.Edited 2006-02-23 20:36

and

if you cant prove something, prove its oposite.

quite over simplified rules, and everyone knows ever rule has an exception....

So the computer DID run but it didn't like a photo can be in multiple places at once even though it appears only in one place at a time? Phheww, Boeing!!

But then I realised: This makes "Deep Thought" look pathetic.

Deep Thought took millions of years to calculate an answer to a question that wasn't known.

This thing almost instantly gave the answer to a question that wasn't asked!

Basically, the problem with Quantum Mechanics as opposed to Regular Mechanics is that Quantum Mechanics is "non-deterministic". What non-deterministic means is that you can't actually just determine what state something is going to be in, just a probability.

One other bizarre related prediction of this theory is that observing something

It's Schrodingers' Cat: Imagine a cat in a box, with a bottle of poison and a radioactive source. If the radioactive source happens to decay (there's only a probability that it will or it won't, like flipping a coin), a hammer will smash the bottle and kill the poor kitty.

Until you open the box, you won't know if the radioactive source decayed and killed the cat. The catch is, according to Quantum Mechanics,

Once you check, the "waveform collapses" into one possibility at random. This has actually been tested and observed (the Stern-Gerlach device, I can't find a good explanation of that actual experiment online), fortunately not with cats (that thought experiment was invented to highlight how absurd the whole idea was)

Albert Einstein hated the idea ("God does not play dice with the universe"), and spent a large portion of his later years trying to prove, essentially, that you really could tell whether or not the cat was dead without checking. (The Einstein-Podolsky-Rosen Paradox) Unfortunately, he wasn't successful.

They have built up a quite clever experiment which **when interpreted as an algorithm** behaves like stated.

I would not draw any more complicated conclussions from that. Quantum **systems** are just that: complicated systems with random behaviour (though statistically sound, usually, in the long run).

The summary, though, is quite bad:

Although a photon can occupy multiple places simultaneously, it can only make an actual appearance at one location.

Typicall mistake. It is a quantum object; it is not in multiple places but everywhere as a function wave. And in "all the states" at once (ibid.)

We are still to have a Shor's factoring machine. That will be a great day.

What's new here?

Not running Windows also solves many problems.

Maybe one day a computer will find the question to an answer that will not have been given.

Methinks my brain windings are becoming straight.

Quantum Mechanics is not an ivory-tower science as perceived by most laymen: without it, your classical computers (yes, the one you are staring at right now!) won't even run.

Personally, I like to keep the intuitive part to a minimum and stick to the equations: What's wrong with probability patterns that just happen to match the wavefunction? We will probably need the String Theory to really explain what really is a photon/electron/etc. (In the mean time, I am hoping the LHC will be finished soon)

Can't wait to see Windows run on any of these future quantum systems (no, I will not make fun of it).

Reading this and related text on Wiki, gives a good insite to quantun computers and science.

http://en.wikipedia.org/wiki/Quantum_computerEdited 2006-02-24 16:58

Its already been done.

http://atomchip.com/_wsn/page4.html

>

> http://atomchip.com/_wsn/page4.html

This is simply incorrect. What is described behind this link is not quantum computer. It doesn't utilize superposition and entanglement, which means it's power is just that of a classical computer.

- Morin

- Morin

It was meant to be a JOKE as we've had many long discussions on these forums about the AtomChip.

> discussions on these forums about the AtomChip.

Oops... sorry then!

- Morin

- Morin

No biggie dude. its all good

A more direct example of quantum mechanics is the experiment with lasers and mirrors.

The setup is a laser fireing into a semi-transparent mirror, where the resulting rays are later collected in another semi-transparent mirror with two detectors on either exit path.

As long as you don't measure anything except the detectors at the end both detectors get 50% of the laser photons.

The quantum weirdness starts when you block one of the two paths. Common sense dictates that 50% of the photons would be lost and the other 50% would be divided in by the last mirror so that the detectors get 25% of the photons each.

But what happends is that 100% of the photons goes to one of the detecors.

I don't know if quantom logic is involved but it certainly seems similar.

In quantum logic there is a concept of a sqrt!() (that is square root of not) function with the properties that

sqrt!(x) == random(2) (where x is 0 or 1)

and

sqrt!(sqrt!(x)) == !x

This also shows why it's impossible to measure quantum systems. If the result of the inner sqrt!() was know the result of the outer sqrt!() would be random, and thus unknown.Edited 2006-02-25 06:06

> philosophical.

I don't really know, but isn't it actually incorrect? The whole example assumes that the box-cat-system doesn't 'collapse' into a specific state, but with macroscopic systems like a cat this is (practically) always the case.

If I remember correctly, then for the same reason quantum computers don't work yet. Their computation is based on superposition of states, but as soon as something interacts with this mess-of-states, it collapses (by biased random choice) into one of those states, destroying the computation (that's as if your computer's RAM lost all its data at random intervals).

- Morin