Visiting Princeton, the American home to Albert Einstein, I’m reminded of one of my favorite “paradoxes” of special relativity. And, even more so, one of my favorite versions of this paradox which, when I first heard it, it blew my mind. What paradox is this of which I speak? The twin paradox of course! Really just the plain old twin paradox? No. Much better than that: the twin paradox in donut space!
Continue reading “Twins in Donut Space”
The Same Title?
On the arxiv Friday:
arXiv:0802.4248
Title: Coexistence of qubit effects
Authors: Peter Stano, Daniel Reitzner, Teiko Heinosaari
Comments: A paper with identical title is being published on the arXiv simultaneously by Paul Busch and Heinz-Jurgen Schmidt. These authors solve the same problem independently with a different method.
and
arXiv:0802.4167
Title: Coexistence of qubit effects
Authors: Paul Busch, Heinz-Jürgen Schmidt
Comments: A paper with identical title is being published on the arXiv simultaneously by Teiko Heinosaari, Daniel Reitzner and Peter Stano. These authors solve the same problem independently with a different method
Chosing the same title seems a bit strange to me. I mean simultaneous result posting happens quite frequently, but with the same title? But at least this answers a question I’ve always had which is whether the arxiv allows papers with the same title.
"Filming" an Electron
On the intertubes today I’m seeing a lot of references to “Electron filmed for the first time” (digg, msnbc, Live Science.) For a decent explanation that doesn’t involve radically distorting quantum theory, I recommend this Physical Review Focus article (and, of course, nothing compares to the original PRL…although it must be said, as always, that four pages is not enough, damnit!) Note that, if I understand correctly, the movie “filmed” above is a movie in “momentum space” and, of course, we’re not really talking about the observation of a single electron, but of the momentum distribution of the coherent electron wave packets. But what really confuses me is what the actual “movie” is supposed to represent.
Continue reading “"Filming" an Electron”
SqUINT Live Blogging – Saturday Talks
Yes we work on Saturdays. Okay work may be the wrong word. Updated as the day goes along and my brain doesn’t fill up (plus I’m chairing a session, so is it ethical to chair and blog at the same time?)
Continue reading “SqUINT Live Blogging – Saturday Talks”
SquinT Live Blogging – Friday Talks
Live blogging from day one of the talks at SquInT 2008. Updated as the day goes along. So hit that refresh button 🙂
Continue reading “SquinT Live Blogging – Friday Talks”
Superconducting Qubit Fidelities Improve
New results out of the Martinis lab at UCSB have shown single qubit gate fidelities of 0.98 for a superconducting phase qubit. This is significantly better than previous single qubit gate fidelities in their system and in any other superconducting qubit system. It is an extremely impressive number. (Seems that carefully crafted microwaves pulses were a big help in getting the gate fidelity to this level.) Martinis is speaking at SQUINT 2008, but just in a tutorial section. Maybe we will get lucky and a bit of these new fidelities will leak into his talk.
Pseudonyms in Science?
A while ago a message from Kris Krogh appeared on Scirate.com about ariXiv:0712.3934 stating Kris’ belief that the paper appeared under a pseudonym (the comment contains the contents of the link which was sent to the arxiv’s administrator.) Today I checked with the arxiv and found that the paper had been removed:
This submission has been removed because ‘G.Forst’ is a pseudonym of a physicist based in Italy who is unwilling to submit articles under his own name. This is in explicit violation of arXiv policies.
Roughly similar content, contrasting the relative merits of the LAGEOS and GP-B measurements of the frame-dragging effect, can be found in pp. 43–45 of: this http URL
Humorously (I guess) while the statement goes to pains to not name the Italian physicist, the link is to a Nature article…by an Italian physicist.
Continue reading “Pseudonyms in Science?”
The Contextuality of Quantum Theory in Ten Minutes
Through my computer science “information is king” eyeglasses, there are really only two notions which thoroughly distinguish quantum theory from classical theories of how the world works: the nonlocal nature of quantum correlations as exemplified by Bell’s theorem and the much less well known contextual nature of quantum measurements as exemplified by the Bell-Kochen-Specker theorem. While the former is well known (and hence, to paraphrase Gell-Mann, what you’ve heard about it is mostly wrong), the later is less well known. Is that because it is a complicated idea? I don’t think so! Indeed I think you can learn what quantum contextuality means in less than ten minutes. Yep, it’s another edition of “explain quantum theory in ten minutes!”
Continue reading “The Contextuality of Quantum Theory in Ten Minutes”
Happenings in the Quantum World: January 16, 2007
Graphene quantum dots as qubits, Quantum Zeno effect, and the APS March meeting.
Continue reading “Happenings in the Quantum World: January 16, 2007”
What Is an Uncomputer?
Sean watches a panel discussion on whether the universe is a computer, looks up the definition of a computer, and decides that instead the universe is a calculation. If thinking about the universe as a computer is designed to make computer scientists feel important, thinking about the universe as a calculation seems designed to make theoretical physicists feel important 🙂 But what I find interesting is that Sean points to a question asked by Tony Leggett: “What kind of process does not count as a computation?”
Continue reading “What Is an Uncomputer?”