El Naschie works on entanglement now

El Naschie (top), shown photoshopped in with three Nobel laureates.

The Journal of Quantum Information Science will not be getting any of my papers starting today, because today is when I learned that they recently published the following gemA Resolution of Cosmic Dark Energy via a Quantum Entanglement Relativity Theory, by M. El Naschie.
Upon closer inspection, it isn’t hard to see why they published this paper. It’s because  “El Naschie is very highly regarded in the community” and is “always spoken of as a possible Nobel prize candidate”. And as the great man himself has said, “Senior people are above this childish, vain practice of peer review”, so there was no need for that.
Oh, but despite the apparent lack of peer review, they do have a $600 article processing charge for open access. I wonder what costs these charges are meant to offset if the “submit” button just puts the article straight into the publication? Hmmm, I hope that the journal didn’t simply accept money in exchange for publishing the paper under the pretense of “open access”! Golly, that would be unethical.

Pop goes the discord bubble

Well, the rat is out of the bag; Schroedinger’s Rat, that is. That’s the new quantum blog by Miguel Navascues and boy is it snarky! I was keeping it under my hat for a while so I could enjoy it privately, but the time has come to announce it to the world. Miguel is fearless about shouting his colorful opinions from the rooftops, and I can respect that, even if I don’t agree with everything he says.
Miguel’s second post is all about quantum discord. As anyone who reads quant-ph knows, there are around two or three papers per week about discord for years now. Unfortunately, a huge number of these are nearly worthless! Quoth the Rat:

The quantum discord of a bipartite state was first defined by Ollivier and Zurek as the difference between its original quantum mutual information and the same quantity after we perform a rank-1 projective measurement on one part.
Now, what does that mean? Probably, nothing. But lack of motivation has never prevented investigation at international scale. And so we ended up with one more research topic that clearly goes nowhere, in the line of entanglement sudden death…

If you thought he was exaggerating, here is a paper that has been cited 263 times since May 2009: Robustness of quantum discord to sudden death. Wow, discord is immortal! And in case you want more, you can just go to quantumdiscord.org and find a list of discord papers and see for yourself.
Before we can treat the patient we have to understand the disease, and this is exemplified by a typically test case: Quantum discord for two-qubit X-states (cited 256 times). The authors compute the quantum discord and a few other entanglement measures for a family of two-qubit states and conclude that there is no obvious relationship between the various measures. Why did they do this? “Because it’s there” might have been a good reason to scale Everest, but this feels more like a homework assignment for a graduate course. Wait, I take that back: Scott’s students’ homework is much more interesting and relevant.
But Steve! What about all the good discord papers? You can’t just trash the entire field! 
You’re absolutely right, there are good discord papers. I can even name about 5 of them, and I’m willing to bet there are as many as 12 or 15 total. My intention is definitely not to trash the subject as intrinsically uninteresting; rather, I want to highlight the epidemic of pointless papers that constitute the discord bubble. I hope that thinning the herd will increase the quality of the results in the field and decrease the hype surrounding it, because it has really gotten completely out of control.
Here are some good rules of thumb for those moments when you find yourself writing a discord paper. If you are calculating something and you don’t know why you are calculating it, then close your latex editor. You do not have one of the good discord papers. If the discord you calculated is not related to a resource (physical, computational, etc.) in a quantifiable way, you probably don’t have a good discord paper. If it is related to a resource, but you had to concoct that relationship in a totally ad hoc way that doesn’t generalize, then you do not have a good discord paper. Ditto if the relationship is via a protocol that literally nobody cares about. If you only have two qubits, you almost certainly don’t have a good discord paper. Good theory papers usually have n qubits. And if your weak theory result suffers from one or more of the above but you add in some equally unimpressive experimental results to cover up that fact, then you absolutely, unequivocally do not have a good discord paper. I don’t care what journal it’s published in, it is not a good paper and you should be ashamed of yourself for inflating the bubble even further.
As bad as the authors are, this bubble is also the fault of the referees. Simply being correct is not enough to warrant publication. It also has to be new, non-trivial, and interesting. Please referees, “Just Say No” to papers that don’t meet this standard!
Enough of this bad medicine. In the comments, feel free to mention some of the actually good discord papers, and why they deserve to keep their value after the bubble bursts.

Physics World gets high on Tel Aviv catnip

It should be no surprise that loose talk by scientists on tantalizing subjects like backward causality can impair the judgment of science writers working on a short deadline.  A recent paper by Aharonov, Cohen, Grossman and Elitzur at Tel Aviv University,  provocatively titled “Can a Future Choice Affect a Past Measurement’s Outcome?” so intoxicated Philip Ball, writing in Physics World,  that a casual reader of his piece would likely conclude  that  the answer was  “Yes!  But no one quite understands how it works,  and it probably has something to do with free will.”  A more sober reading of the original paper’s substantive content would be

  •  As John Bell showed in 1964, quantum systems’ behavior cannot be explained by local hidden variable models of the usual sort, wherein each particle carries information determining the result of any measurement that might be performed on it.
  • The Two State-Vector Formalism (TSFV) for quantum mechanics,  although equivalent in its predictions to ordinary nonlocal quantum theory, can be viewed as a more complicated kind of local hidden variable model, one that, by depending on a final as well as an initial condition, and being local in space-time rather than space, escapes Bell’s prohibition .

This incident illustrates two unfortunate tendencies in quantum foundations research:

  • Many in the field believe in their own formulation or interpretation of quantum mechanics so fervently that they give short shrift to other formulations, rather than treating them more charitably, as complementary approaches to understanding a simple but hard-to-intuit reality.
  • There is a long history of trying to fit the phenomenology of entanglement into inappropriate everyday language, like Einstein’s “spooky action at a distance”.

Surely the worst mistake of this sort was Herbert’s 1981 “FLASH” proposal to use entanglement for superluminal signaling, whose refutation may have hastened the discovery of the no-cloning theorem.  The Tel Aviv authors would never make such a crude mistake—indeed, far from arguing that superluminal signalling is possible, they use it as a straw man for their formalism to demolish.   But unfortunately, to make their straw man look stronger before demolishing him, they use language that, like Einstein’s,  obscures the crucial difference between communication and correlation.  They say that the initial (weak) measurement outcomes “anticipate the experimenter’s future choice” but that doing so causes no violation of causality because the “anticipation is encrypted”.  This is as wrongheaded as saying that when Alice sends Bob a classical secret key, intending to use it for one-time-pad encryption,  that the key is already an encrypted anticipation of  whatever message she might later send with it.   Or to take a more quantum example, it’s like saying that half of any maximally entangled  pair of qubits is already an encrypted anticipation of whatever quantum state might later be teleported through it.
Near the end of their paper the Tel Aviv group hits another hot button,  coyly suggesting that encrypted anticipation may help explain free will, by giving humans “full freedom from both past and future constraints.”  The issue of free will appeared also in Ball’s piece (following a brief but fair summary of my critique) as a quote attributing to Yakir Aharonov, the senior Tel Aviv author, the opinion that  humans have free will even though God knows exactly what they will do.
The authors, and reviewer, would have served their readers better by eschewing  the “concept” of  encrypted anticipation and instead concentrating on how TSVF makes a local picture of quantum evolution possible.  In particular they could have compared TSVF with another attempt to give orthodox quantum mechanics a fully local explanation,  Deutsch and Hayden’s 1999 information flow formalism.

Hoisted From the Comments: Quantum Marriage

Charlie Bennett comments about an novel use of quantum entanglement:

Tracy Staedter describes a quantum wedding apparatus built by conceptual artist Jonathon Keats, which briefly entangles two people by illuminating them with entangled photons. Staedter quotes Keats as saying the resulting quantum marriage would literally be broken up by skepticism about it.

Speaking of which, who was it who introduced the idea of monogamy of entanglement?
(Anyone want to go into business selling a device which shoots entangled photons at you and a nearby person? “The Quantum Entangler” could be used to entangle you with that nearby hottie who you really want to get to know 🙂 )

Entangled in the Membrane, Entangled in the Brain?

Bad New Scientist has an article up today entitled Brain ‘entanglement’ could explain memories, which certainly must have sent Roger Penrose’s brain into a state of multiple correlated back-flips (twistor flips?) However, from the article:

Subatomic particles do it. Now the observation that groups of brain cells seem to have their own version of quantum entanglement, or “spooky action at a distance”, could help explain how our minds combine experiences from many different senses into one memory.

First of all, damnit New Scientist, entanglement is not just between “subatomic particles.” Second of all, the effect described is as similar to spooky action at a distance as the fact that when you look at my feet you’ll most likely see that I have the same color sock on both of my feet. To suggest that the effect described in this PLOS biology paper where they observed correlated local field potential mesurements in a monkey’s brain has got anything to do with quantum entanglement is…well…just plain wrong.
(Which is not to say that quantum effects might not arise in the brain: we simply don’t have any evidence of such effects and speculations about such effects arising are, so far, physically implausible. I.e. that’s how a scientist says: probably not, but I’m always ready to change my opinion with some good hard evidence.)

New York Times Film Review Fail

This morning Mrs. Pontiff read me a review out of the New York Times for the film “A Serious Man.” The opening paragraph of the review gives you an idea why she thought it might be relevant to me:

Did you hear the one about the guy who lived in the land of Uz, who was perfect and upright and feared God? His name was Job. In the new movie version, “A Serious Man,” some details have been changed. He’s called Larry Gopnik and he lives in Minnesota, where he teaches physics at a university. When we first meet Larry, in the spring of 1967, his tenure case is pending, his son’s bar mitzvah is approaching, and, as in the original, a lot of bad stuff is about to happen, for no apparent reason.

Cool, a physicist playing Job. But then she read me the second paragraph and it all soured for me:

At work, Larry specializes in topics like Schr√∂dinger’s Paradox and the Heisenberg Principle — complex and esoteric ideas that can be summarized by the layman, more or less, as “God knows.” Because we can’t. Though if he does, he isn’t saying much.

Egads New York Times (okay maybe that should be a singular “egad” given the context) what are you trying to do to this old physics curmudgeon and literature major pedant early in the morning, give him a heart attack?!?
Dear Mr. New York Times reviewer A. O. Scott, the proper words you were looking for here are “Schr√∂dinger’s Cat Paradox” and “Heisenberg’s Uncertainty Principle.” If you’re going to take a mocking tone in your review about “complex and esoteric ideas” it would be useful, you know, if you actually got the names of those “complex and esoteric ideas” correct. Second isn’t it sad how a film critic can get away with calling these two ideas “complex”? Compared to what Mr. Scott? Compared to the proof of the PCP theorem? Compared to doing a calculation in quantum field theory? Um, I don’t think so. And finally, because standing on this upside down can is getting kind of wobbly, isn’t it a little presumptuous of you to say that God knows the position and the momentum of a particle? I mean might it be that even God doesn’t know the hidden variables of our universe. Or even, heaven forbid, that there are no such variables, and that *gasp* he is not in control of the universe that he supposedly created?

Through The Eye of the Beholder

Scott the optimizer asks a question on a wim:

Come up with a catchy name for growth rates of the form 2^(n^&alpha) , 0< &alpha<1.

I thought the answer was obvious: “probably in BQP.”
update: does html superscript not work in a blockquote? I guess the answer is yes.