This article gets the paper totally wrong. Learning that the uncertainty principle gives rise to phenomena that popular science calls "wave-particle" duality was taught to me in quantum 101.

From the abstract: "This idea...upper bounds the sum of the interference visibility and the path distinguishability. Such wave-particle duality relations (WPDRs) are often thought to be conceptually inequivalent to Heisenberg's uncertainty principle, although this has been debated."

I'm quite surprised that anyone would think that those relationships wouldn't be direct consequences of uncertainty. They are directly analogous to position and momenta quantities.

"Here we show that WPDRs correspond precisely to a modern formulation of the uncertainty principle"

No surprises here.

Perhaps I was mistaken, but I thought this was sort a necessary revelation when learning about QM. It's been years since I took Atomic Physics, so perhaps this is something much ... deeper?

Was it a serious idea that upon measurement the particle literally lost it's wave properties? Like, there were actually two separate approaches to the math? I know we made some efforts to simplify in class, approximating as particles and such due to the drastically simplified math, but we all knew that was happening; the professor was reasonably explicit about it. EDIT: As in, I remember us going over the evolution of a waveform, and how boundaries affect the solutions, and how uncertainty causes the particles to have field distributions that just happen to be the wave solution of the particle.

I'm completely serious about being confused here: QM is super easy to misunderstand, and I'd love to feel the eureka this article is trying to convey.

<armchair physicist>

I love reading about these things. It seems like information is slowly being raised to the same level as energy and matter (All being different ways to look at the same phenomenon)

The universe does care about preserving information, and there are physical limits on it's propagation and consumption. This is similar to formalizing energy as a concept, which can manifest itself in many different ways (kinetic, potential, radiation, etc) Once we wrapped it up in a concept we were able to reason about it in a more abstract way. The same process is now happening with the concept of information. This is leading to breakthroughs in computing (ML, pattern recognition, etc) and physics. I am excited for the future of information theory.

</armchair physicist>

I'm no theoretical physicist, but I thought wave-particle duality was solved a long time ago by quantum field theory. Feynman, for instance, was able to formulate electromagnetism fully in terms of particles, using his path integral formulation. Since this formulation computes probability amplitudes, it seems to fit well with the uncertainty principle. This approach gave rise to QED, the most accurate physical theory ever developed.

In other words, without more detail, and not being a physicist myself, I can't tell what's actually new here.

http://arxiv.org/pdf/1403.4687v2.pdf is the actual preprint.

I'm finding it pretty hard to parse. It seems to be a reformulation of what we already know about non-commuting observables in terms of entropy/ignorance. I might need to read some of the cited papers to understand exactly if that's significant and why.

I know that many people feel that you have to write like this to get anyone to pay attention (maybe they're right), but after enough years in physics, the breathlessness of this kind of reporting really starts to grate.

> international team of researchers has proved

> made the breakthrough

> discovered the 'Rosetta Stone'

I haven't read this particular article carefully, but I think it's safe to assume that words like "reformulated," "clarified," "extended," or "embedded in a new framework" would be more appropriate. Which is fine. New and better explanations are useful and important.

But despite what you may read, we don't find a new Rosetta Stone for quantum physics every year.

I get much more excited about science writing where the reader can come away with a better understanding of an actual concept, rather than just a sense that someone somewhere is doing something hard and smart.

http://arxiv.org/pdf/1403.4687v2.pdf

Feynman on the "work" of gravity theorists: "something correct that is obvious and self-evident, but worked out by a long and difficult analysis, and presented as an important discovery"

To be fair, this case is the fault of the journalist(s), not necessarily the research itself.

> The particles pile up behind the slits not in two heaps as classical objects would, but in a stripy pattern like you'd expect for waves interfering. At least this is what happens until you sneak a look at which slit a particle goes through - do that and the interference pattern vanishes.

Could any of the physicists here verify whether it is the case that detecting the slit the particle passes through destroys the interference pattern. I had the impression that the path of the photons could be determined without destroying the pattern.

Tangential comment: if you are interested in quantum mechanics then you may be interested to read about "Bohmian Mechanics".

I became interested in Bohmian Mechanics after reading an email exchange between Sheldon Goldstein & Steven Weinberg [1]. It contains a few quite entertaining quotes, in particular:

    > And since Bohm’s equations make exactly the same
    > predictions as those of ordinary quantum mechanics,
    > it is not clear what is accomplished by adding the
    > complication of guiding waves, except to restore a
    > sense of sanity to the whole affair.

    > Again, the amazing thing about this theory is that it's
    > deterministic: specify the "actual" positions of all the
    > particles in the universe at any one time, and you've specified
    > their "actual" positions at all earlier and later times.

Some proponents of Bohmian Mechanics point out that the theoretical predictions of deterministic particle trajectories for the famous double-slit experiment agree with recent experimental results.

Theoretical predictions: see Figure 1, page 14 of [3], which is an adaptation of a figure from [4].

Experimental results: see Figure 3, page 1171 of [5].

Note that [5] carefully frame their experimental results as "Using weak measurements, however, it is possible to operationally define a set of trajectories for an ensemble of quantum particles".

For further reading, please see [6] for links to introductory writing about Bohmian Mechanics.

[1]: http://inference-review.com/article/on-bohmian-mechanics

[2]: http://www.scottaaronson.com/democritus/lec11.html

[3]: http://www.mathematik.uni-muenchen.de/~bohmmech/BohmHome/fil...

[4]: "Quantum interference and the quantum potential" -- Philippidis, Dewdney, Hiley -- Il Nuovo Cimento B, 1979; [paywalled article] -- http://link.springer.com/article/10.1007/BF02743566

[5]: "Observing the Average Trajectories of Single Photons in a Two-Slit Interferometer" -- Kocsis, Braverman, Ravets, Stevens, Mirin, Shalm, Steinberg; Science, 2011 -- [PDF] http://materias.df.uba.ar/labo5Aa2012c2/files/2012/10/Weak-m...

[6]: http://www.bohmian-mechanics.net/whatisbm_introduction.html

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