Defeating Heisenberg's Uncertainty Principle

eldavojohn writes "As we strive closer and closer to quantum computing, physics may need to be improved. A paper released in Nature Physics suggests that the limit defined by Heisenberg's Uncertainty Principle can be beaten with quantum memory. From the article, 'The cadre of scientists behind the current paper realized that, by using the process of entanglement, it would be possible to essentially use two particles to figure out the complete state of one. They might even be able to measure incompatible variables like position and momentum. The measurements might not be perfectly precise, but the process could allow them to beat the limit of the uncertainty principle.' Will we find out that Heisenberg was shortsighted in limiting the power of quantum physics or will the scientists be surprised to find that such a theoretical scenario — once conducted — performs unexpectedly in Heisenberg's favor?"

Comments

1st and second post :-)

[Stooshie]

1st and second post simoultaneously :-)

Re:1st and second post :-)

[Arancaytar]

I was able to observe your post, but not how fast you typed it. The limit remains unbroken, I guess.

Re:1st and second post :-)

[Tubal-Cain]

Report just in: It wants and does not want a cheeseburger.

Re:Sounds as if...

[shikaisi]

well, it is and it isn't.

Related Funny On Top Gear Last Night

[Richard_at_work]

They demoed the Ferrari 458, and one of the "features" that Jeremy Clarkson highlighted was that the dash mounted display could show you either the speedo or the GPS Sat Nav, but not at the same time - my immediate thought was "Heh, someone at Ferrari has a sense of humour and knows what the Heisenbergs Uncertainty Principle is." :)

Re:So was Heisenberg right or wrong?

[Eudial]

Heisenberg's uncertainty principle is still a fundamental cornerstone in quantum physics. Incompatible observables remain incompatible. What the article says isn't that the principle is wrong, but that there is a work-around for a technical problem which the principle was causing. Much the same way the invention of airplanes did not imply gravity is wrong.

That's all I can say without seeing some math.

Re:So was Heisenberg right or wrong?

[NevarMore]

That's all I can say without seeing some math.

2+2=5. There you've seen some math, now please continue.

Bad choice of names?

[Krokant]

For those interested, the preprint of the Nature article can be found at: http://arxiv.org/abs/0909.0950

However, I don't really see what the fuzz is about. What they are in fact demonstrating is a relationship between conditional von Neumann entropies, which they claim is a measure of "uncertainty" (it is in a specific meaning of the word "uncertainty"). However, there is a difference between von Neumann entropy and the variance of a physical observable as used in the Heisenberg uncertainty principle. On the other hand, if you label a physical property such as entropy "uncertainty" and demonstrate a relationship between those entropies, then you can indeed call that an "uncertainty relation" but that's just a cheap way of attracting attention.

Also, I am not sure if it is possible to obtain the Heisenberg uncertainty relation from their equation. I would expect that, for example by entering pure, disentangled states in their equation, that Heisenberg should be recoverable (because of course, Heisenberg also applies to pure states). I don't immediately see how that can happen since the von Neumann entropy for a pure state is zero. Perhaps I am just missing something and perhaps my QM is a bit rusty :).