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Why are man-hole covers round? - http://www.guardian.co.uk/money...
Some neat Google interview questions (in the finest Oxbridge tradition). - Dan Browne from Bookmarklet
ETH - QIP 2010 Rump Session - http://www.qip2010.ethz.ch/rumpses...
Unflattering name, but great idea. QIP gets a ''rump session''... - Dan Browne from Bookmarklet
Can anyone recommend a nice friendly introductory textbook for linear algebra for the non-mathematician?
SciRate Page For 0910.1396 "Sudden Death of Entanglement" - http://scirate.com/who...
Unusually aggressive comments on SciRate... - Dan Browne from Bookmarklet
RT @vaughanbell Stephen Hawking resigns Cambridge Professorship. Awesome multimedia resignation statement. http://news.bbc.co.uk/2...
I love the conclusion ;-) - Anthony Leverrier
UCL 1960 Freshers Week - http://www.youtube.com/watch...
UCL 1960 Freshers Week
Play
Has hardly changed... - Dan Browne from Bookmarklet
Quantum Nobel Laureates? - Thomson Reuters predictions - http://thomsonreuters.com/content...
via @quantumtunnel Anyone know how successful their predictions have been in the past? - Dan Browne from Bookmarklet
Though obviously the smart money is on @dabacon and his quantum transistor... - Dan Browne
Either of the other two sound more plausible than Cirac and Zoller. - Matt Leifer
quzistor for the win :) We should all redouble our efforts to build a quantum computer so that Cirac and Zoller and Shor et al get their Nobel before they die (qc timescales are depressing?) - Dave Bacon
The BBC maps out the global growth of internet subscribers and undersea cables over the last 10 years. - http://news.bbc.co.uk/2...
APS website search-box much improved. Now worth setting up as a keyword search in Firefox or Safari. URL pattern is: http://link.aps.org/citesea... where #query# denotes the query string. Useful.
Medical Hypotheses fails the Aids test – Bad Science - http://www.badscience.net/2009...
And have a look at the papers he links too. Gobsmacking. http://www.badscience.net/2007... - Dan Browne
The thing I miss most about working at Oxford University? Staff are exempt from library fines. Not so at UCL... (No, I really do miss that more than the high table dinners - honest)
I keep getting letters from my university library threatening to not let me graduate due to outstanding fines. Somehow they haven't touched a nerve yet... - Alexei from BuddyFeed
Quantum Solution to the Arrow-of-Time Dilemma - http://scitation.aip.org/getabs...
"Arrow-of-time" dilemma becomes "which-paper-to-believe" dilemma. - Dan Browne
Treatment of Alan Turing was “appalling” - PM | Number10.gov.uk - http://www.number10.gov.uk/Page205...
[0909.1469] Towards Quantum Superposition of Living Organisms - http://arXiv.org/abs...
TextMate — The Missing Editor for Mac OS X - http://macromates.com/
Roadtesting textmate as a replacement LaTeX editor for TeX Shop. So far I'm impressed. Have a lot of TeXing to do in coming weeks so let's see how it fares... - Dan Browne from Bookmarklet
Redacted! Just realised that the article I linked to had violated a press embargo, and by linking to it I did too. :-o Will unredact this evening!
Really? Unless it was your own article and you entered into a contract with the publisher I don't see how you could have violated anything. - Matt Leifer
Besides, press embargoes are silly. - Matt Leifer
Possibly, but since I had received an advance copy of that paper in confidence (I was interviewed by a different magazine about the article) it seemed inappropriate. Anyhow, the embargo is lifted in 2 hours - bet you can't wait to read the paper now! - Dan Browne
I really ought to tame my exclamation-mark habits - look at them all over my comments - horrid! (Darn, did it again...) - Dan Browne
I saw a similar article on another site several hours before the embargo was over, so I guess the whole redaction palaver was pretty meaningless. - Matt Leifer
You are right. It was rather an overreaction - never mind... - Dan Browne
Computer Shopper: News: Bristol University demonstrates world's-first optical quantum computer - http://www.expertreviews.co.uk/news...
Now unredacted. :-) The rest of the article is more accurate than the headline... - Dan Browne from Bookmarklet
It seems like a pretty cool result. Photon interactions are hard. - Matt Leifer
The article doesn't mention what journal this is going to appear in. I am guessing it is Nature. Their embargo policy is silly. - Matt Leifer
It will appear in Science on 4th September. Yes, you are right that embargos are rather odd. - Dan Browne
PDF enhancements in Snow Leopard are a real boon for academics - One can finally properly select text in a two-column document, and the loading and printing of PDFs seems greatly sped-up. That annoying bug which caused equations to be corrupted on printing (all horizontal lines were removed from Latex equations!) also seems now to be fixed.
I spoke too soon - Latexit is hosed! :-o - Dan Browne
Now downloading pre-release beta of new MacTex... gulp! - Dan Browne
LatexIt seems to have fixed itself. It crashed - I restarted it, seemingly wiped its own prefs file and now it appears to work. :-) No beta version of MacTex necessary.... (phew!) - Dan Browne
[0907.0372] A glance beyond the quantum model - http://arxiv.org/abs/0907.0372
Navascues and Wunderlich introduce the principle of "macroscopic locality", the idea that if one course-grains measurements over many copies of an entangled state in a suitable way one should obtain results concordant with a classical local theory. They are able to derive limits on the correlations supported by any theory in which this principle is respected. Remarkably, this coincides with the set Q1 of correlations, a first set of correlations which arises in the hierarchy of SDP bounds introduced by Navascues and co-authors, which converges to the set of quantum correlations. The natural question to ask is whether one can find similar operational interpretations for the remaining SDPs in the hierarchy. - Dan Browne from Bookmarklet
I like this paper a lot. However, I feel that their definition of macroscopic locailty is somewhat unnatural. Indeed, they consider measurements over N i.i.d. states when one only has access to detectors with a resolution on the order of sqrt(N). What bothers me a little is this i.i.d. structure they impose. Why not consider instead the more natural notion of "symmetric states" ?... more... - Anthony Leverrier
Anthony: It is clear that a de Finetti theorem would hold in (most reasonable) post-quantum theories http://arxiv.org/abs/0712.2265 However, you didn't specify whether a finite theorem was needed or an infinite theorem is OK. I suspect there is a finite theorem as well, but it is difficult to get a bound that scales reasonably for all possible state spaces that might occur in a post-quantum theory. - Matt Leifer
Matt: thanks for the reference. I haven't had time to read it thoroughly yet, but I'm a little bit surprised as there are known simple counter examples to de Finetti theorem in Quantum Mechanics as soon as the dimension of the Hilbert space is infinite , for instance the completely antisymmetric state (ie the N particles generalization of the singlet state) which is symmetric but cannot be approximated by mixtures of iid states. How does your result deal with such states ? - Anthony Leverrier
It doesn't. It is restricted to finite dimensional state spaces. I am not sure your example is right though because it does not appear to be exchangeable. - Matt Leifer
This counterexample was studied in quant-ph/0602130 (example II.9), and is usually the best argument against direct generalisations of (the finite version of) de Finetti theorem to infinite dimensional spaces. Coming back to the macroscopic locality discussion, I think a finite version of dF would be needed, and maybe an exponential version such that only a negligible fraction of the... more... - Anthony Leverrier
I agree that symmetric is more natural that i.i.d. Thanks for reminding me about the counter-example. I was confused because your example was finite-dimensional, but looking at the paper I was reminded that it is the scaling of the distance bound with dimension that is the culprit. I think there *must* be a finite version for the general framework of the paper I referenced because we... more... - Matt Leifer
[0908.3408] Entangled quantum states in a local deterministic theory - http://arXiv.org/abs/0908.3408
T'Hooft argues that one can obtain an apparent violation of Bell inequalities in a local deterministic theory. I haven't had a chance to work through his argument carefully, but am suspicious, not least due to the verbose argument which seems to lack a clean mathematical formulation. Like all "disproofs" of Bell's theorem, it is likely to be flawed, but one often learns a lot from finding the flaws in the argument. And then again, you don't win a Nobel prize for nothing...! - Dan Browne
I've never been able to work out enough of what is going on in t'Hooft's quantum papers to figure out whether he has made an error or is just using language in a different way from the rest of us, e.g. what is his definition of local? If there were a Nobel prize in obfuscation then he might have been awarded a second by now. - Matt Leifer
André-Michelle's ToneMatrix - http://lab.andre-michelle.com/tonemat...
It's now quite old and much copied - but still great. - Dan Browne from Bookmarklet
xkcd - Tech Support Cheat Sheet - http://xkcd.com/627/
I've been there so many times - xkcd gets it bang on the nail, yet again. - Dan Browne from Bookmarklet
BBC NEWS | Science & Environment | Science ponders 'zombie attack' - http://news.bbc.co.uk/2...
"Scientists prove zombie could wipe out humans..." - Dan Browne from Bookmarklet
Another example of scientific PR gone mad? Or an excellent piece of science / maths outreach? - Dan Browne
I'm probably a bit slow to this party, but I just found out that one can subscribe to RSS fields for a *particular section* in PRL. Here's the quantum information one: http://feeds.aps.org/rss...
Just discovered the "paper recommendation" feature on SciRate.com (like a Last.fm for scientific articles). Very impressive! It has given me a reading list for some upcoming long flights and, perhaps reassuringly, it seems keen to recommend my own papers to me...
It's not Last.fm it is Digg. It doesn't "scrobble" the papers you are reading but is based purely on voting behavior. - Matt Leifer
Ah yes, good point. It does seem to work pretty well though. - Dan Browne
Nascent: Igor - a Google Wave robot to manage your references - http://blogs.nature.com/wp...
This looks great. Google Wave can't get here soon enough! via @CameronNeylon - Dan Browne from Bookmarklet
Realised that I made a FF newbie faux-pas. "Comment, don't retweet". Cameron's post is here: http://ff.im/5LHDi - Dan Browne
But you also made another more subtle mistake. Since you liked Cameron's post, it will appear in the feed of anyone subscribed to you. Since both your post and his have the same link in them they will be bundled together by FF. Therefore, anyone who sees this post does not need the link to Cameron's post. (BTW, you can use the "share" feature if you want to do the FF equivalent of a retweet rather than just commenting. It is useful if you want to crosspost something to another service.) - Matt Leifer
Thanks Matt! On 27 Jul 2009, at 11:27, Matt Leifer wrote: - Dan Browne from email
Is there a quick-start guide for friendfeed anywhere? Im trying to figure out how much it is / is not like twitter. e.g. what is the ff analog of @names and #tags?
There aren't any. You don't need @replies because you can comment on any post and the person who wrote it will see it. Comments also remove the need for retweets. As for #tags, they are not really needed even on Twitter. FF has a number of other very useful features, such as groups, friend lists, saved searches and imaginary friends, which you should play around with. Personally, I've never looked at any documentation, but I'm sure it is there somewhere. - Matt Leifer
Dan - tags work as per twitter. - Michael Nielsen
The FF FAQ is here http://friendfeed.com/about... It is also worth checking out http://blog.friendfeed.com for information about new features. Unfortunately, the FAQ is not very descriptive, e.g. it describes how you can create a friend list, but not why you would want to or what you can use them for. One day I will write several blog posts about how to organize your entire life on FF. - Matt Leifer
Oh yeah, I forgot that FF recognizes Twitter tags automatically. - Matt Leifer
Thanks Matt and Michael. I am starting to see that FF can be very powerful. It certainly seems a great way of having informal public discussions on a topic, as I am experiencing over on dabacon's feed. - Dan Browne
Just hover over the "#tags" in your question or the comments and you'll see how tags work on FriendFeed. - Neil Saunders
Thanks Neil. That's neat. - Dan Browne
I didn't realize that hashtags worked for more than just Twitter updates... I'll have to make use of that in the future. - Christopher Granade
Twitter and friendfeed are not competing similar services. One is mostly short bursts of test with optional links, the other is a lifestreaming service that aggregates activity from other sites. Don't let that oversized text-box up there fool you. You'll get the most out of friendfeed if you hook up a lot of feeds to your account here. (IMO) - Mr. Gunn
+1 MrGunn. (Hey, that rhymes.) What makes FF so useful to me is that it pulls into one page nearly all of the online activity of the people I follow -- and hopefully, my infostream is similarly useful to others. - Bill Hooker
Yes, it does rhyme. It rolls pleasingly off the tongue. Perhaps everyone could adopt it as a mantra and chant it repeatedly. - Mr. Gunn
Well, there are enough third-party web services that you can lifestream on Twitter if you want to and that big text-box does mean that you can microblog on FF if you want to. You can very well use both services for whatever you like, regardless of what they were designed for. The only advantage that Twitter has is the vast number of users. - Matt Leifer
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