Quantum Computing: No Turning Back

[Telos]

http://www.physorg.com/news3394.html

This article is actually about an article in Nature, but the actual Nature article is still too new for it be up on their website. It's very short, so I'll paste it all right here.

The first realizations of 'cluster states' and cluster-state quantum computation are reported in Nature this week (10 March issue, pp169-176). This represents a significant move from theory to reality for an alternative approach to quantum computing first proposed in 2001.

Anton Zeilinger and colleagues (University of Vienna, Austria) take Robert Raussendorf and Hans Briegel's ideas for computing, based on highly entangled clusters of many particles - in this case photons - and demonstrate that modifications to the entangled photons in such a state allows them to perform certain computing tasks. The entangled photons allow the system to encode information before computations begin and imprint a quantum logic circuit on the state, destroying its entanglement and making the process irreversible. Hence the name 'one-way quantum computing' for the system.

This article reports the first experimental demonstration of the one-way quantum computer, which radically changes how we think about quantum physics and opens up exciting possibilities for the experimental implementation of quantum computation.

It's just stuff like this that orients me back to thinking that quantum mechanics really is mechanical.

[beavis]

which side a coin lands on is random until you know the laws of physics controlling its movement

but quantum still might be random at its core

[Ybom]

Beavis,
Which of the three sides of a coin do you usually end up landing on?

[Nay]

Hehehe...Three sides, ybom... would that be not, tails, heads but middle?

Nay

[beavis]

ybom, the most common 2 sides




Why should I think I know if quantum is random or not? Science doesnt know a deterministic equation for it so it says its random, but that doesnt mean no deterministic equation exists that can describe what science overlooks.

[Telos]

Yes, and it's not *completely* random either.

Statistical quantum mechanics has been incredibly successful. Probability functions have been standing the test of time for about 80 years now. There is some type of regularity.

[Psan]

Nobody says it random. At least in a good book.
They call it unpredictable.
So some things are predictable by equations some are not.

[Telos]

Nobody says it random. At least in a good book.

Brian Greene must not be a very good author then.

[Psan]

He must have said it in public.
You know, to simplyfy things.

Btw, you must have read about the RNG experiments that prove some kind of collective consciousness. That implies that they are not random at all. Ironic.

[Telos]

He must have said it in public.
You know, to simplyfy things.

Nope. I've quoted a passage in the entanglement thread where he italicizes it. And, as I look at the book now, he has probably used the word more than 30 other times to describe the results of quantum measurement.

There is an equal probability that the "spin" of a particle will be changed to clockwise or counterclockwise after a measurement. The axis of the spin also changes within a probabilistic degree. If we cannot predict it, statisticians say randomness is at work.

Btw, you must have read about the RNG experiments that prove some kind of collective consciousness. That implies that they are not random at all. Ironic.

I have. The RNG experiments don't "prove" anything other than a correlation between global events and changes in RNGs. It's definitely worth investigating, but it's premature to close our minds over conclusions such as yours.

And, actually, yes - they're still random. We cannot predict what the outcomes will be without a degree of chance. That says there is a random element.

I'm sure we're just mincing definitions. Mathematicians and scientists refer to def #2. You might be interpreting the word in the context of the phrase "at random," which implies no governing system at all. Quantum probability waves do not occur "at random" but behave randomly.

Unlike pregnancy, you can be a little bit random.

1. Having no specific pattern, purpose, or objective: random movements. See Synonyms at chance.

2. Mathematics & Statistics. Of or relating to a type of circumstance or event that is described by a probability distribution.

3. Of or relating to an event in which all outcomes are equally likely, as in the testing of a blood sample for the presence of a substance.

Sorry to be snotty.

[beavis]

Psan

Nobody says it random. At least in a good book.
They call it unpredictable.

Anything thats not predictable (with good enough measuring equipment, including nonphysical devices) must be random.

If something doesnt depend on anything that exists, it must be random. If it does, the thing it depends on can be used to predict it.

So some things are predictable by equations some are not.

Just because you dont know the equations doesnt mean they dont exist.

I'm sure we're just mincing definitions. Mathematicians and scientists refer to def #2. You might be interpreting the word in the context of the phrase "at random," which implies no governing system at all. Quantum probability waves do not occur "at random" but behave randomly.

Lets talk about the random parts.

Absolute value of any random number, repeatedly subtract 1.0 until its in range 0.0-1.0. Now it behaves "randomly" instead of "at random", but the truly random number can still be behind it and in a very specific and localized way.

There is a purely nonrandom part and maybe a purely random part, but partially random is a bad description.

[Telos]

There is a purely nonrandom part and maybe a purely random part, but partially random is a bad description

You're right. I apologize.

I guess this whole global consciousness thing is making me think of a randomness "fudge factor."

[Psan]

Telos,
Nothing against Mr Greene, he is a good man , but calling a result random actually means that we dont know how we got that result, not that there are no laws working behind it.

Its a separate argument altogether -  whether pure randomness exists or not. But scientists do assume randomness to make calculations simpler and even possible. For example, we usually assume that the motion of molecules in a gas inside a container is random and proceed to calculate the macro quantities. Its better to assume such than to calculate a result of 10^100 interactions and add them up

If we cannot predict it, statisticians say randomness is at work.

When the number of variables is huge, we must resort to statistics to avoid a mental breakdown.

There is an equal probability that the "spin" of a particle will be changed to clockwise or counterclockwise after a measurement.

When you talk in terms of probability you have already assumed randomness. Logic says that you cannot derive it again from the same statement.

The RNG experiments don't "prove" anything other than a correlation between global events and changes in RNGs.....<snip>...And, actually, yes - they're still random. We cannot predict what the outcomes will be without a degree of chance.

You are self contradictory here. A correlation rules out randomness necessarily.
But thats right that its premature, it can be something else. Anyway the involvement of human consciousness is proved, if not of an existence of global one.

[Telos]

Psan, I aced a year of college-level business statistics (although to be fair that isn't saying much). "Randomness" is a model element, and Greene uses the term this way (as scientists generally do) as an aid for description and explanation.

All models are provisional. There are no crises about assumption.

correlation rules out randomness necessarily.

No it doesn't. "Correlation does not imply causation." I think our statistics professor said that to us every single day. No joke.

If you're interested in reading more, the statement you just made is discussed in academia as magical thinking.

[Psan]

If something doesn't depend on anything that exists, it must be random.

Or that we are not aware of existence of a thing on which the so called random event depends, and must assume that its truly random.

Given that non-causality and backward causation exits, we need a better definition of randomness.

[Psan]

"Correlation does not imply causation."

Its when you falsely assume that one of the two co-related quantities is a cause of the other. It may happen that both are caused by a third quantity. And I totally agree. Still it doesnt make any of the events random.
Even if you assume that global events are not causing RNG deviations, you cannot say they are random, because they are not independent. If they were independent, we'd have got insignificant correlation or a pseudo-correlation at most.

[Telos]

It may happen that both are caused by a third quantity

Or by 6.5 billion other quantities - in this case, the population of the world. Or, to be extreme, by every other quantity in the universe. Randomness is generally believed to be caused by an obscenely large number of inputs.

Statistical "independence" is a term for narrow contexts. In the widest context, nothing is independent, and this can be shown both theoretically and empirically, albeit to very small extents. So, in the absolute widest context, nothing is "random," because randomness loses its applicable context.

We're both preaching to the choir on this one.

[Psan]

Or, to be extreme, by every other quantity in the universe.

Now that you've said it, let me second it.
Everything in universe is affected by every other thing, including the non-physical and past/present/future events.

[Rob]

Psan - the founders of quantum mechanics (was it Bohm who argued this against Einstein? I think so) considered the very basis to be statistical. Ie that it is impossible to get beyond the statistics, and that they are at the very core of how the quantum world works.