Category Archives: Uncategorized

Today's talks at Perimeter Institute: Gravity waves, Measurement-based quantum computation

Posted on by
Reply

A few talks you might consider watching online:

Today (now yesterday, actually)'s colloquium.  Patrick Brady gives a nice accessible introduction to gravity waves and the current LIGO observation program, as well as what we may see when Advanced LIGO comes on line in a few years.  Some enlightening animations.  Recommended for: General Audiences. Mild equations.

Very cool ideas, very well presented, from Stephen Bartlett yesterday in the PIQuDos (Perimeter Institute Quantum Discussions series) on how the ability to do quantum computational gates---in this case, single qubit gates---in a measurement-based quantum computational model using the ground state of a lattice Hamiltonian as a resource---can in some cases be modeled by an order parameter, the expectation value of a "string" of operators on adjacent lattice sites that are related to the measurements you need to do to effect the gate.  Phases---regions of parameter space in the parametrized family of Hamiltonians---exist for which the order parameter indicates these gates work well for measurement-based QC purposes.  In particular, the qubit has to be "moved" through the lattice as a "circuit" is simulated, and in a "good" phase, the fidelity of the state of the moved qubit to the state before it's moved, is independent of how far it has to be moved.   An excellent talk.  Recommended for: quantum computation wonks, condensed matter physicists, and a general physics audience interested in getting an idea of the cutting edge of interaction between quantum information/computation and condensed matter physics.  If you're looking for interesting but possibly hard open problems, this talk certainly suggests some.

Bastianich 2008 Sauvignon Blanc

Posted on by
Reply

Had a glass of "2008 Bastianich Sauvignon Blanc" at Bayona in New Orleans. I'm assuming it's the one listed on the net as from the  DOC "Colli Orientali del Friuli" (at Bayona they listed it as from "Venezia", but since the Colli Orientali del Friuli are in the autonomous region of Friuli-Venezia Giulia, that's probably the one).  Fantastic! Hints of grassiness (in a good way), minerality, raciness. Balanced, not high-alcohol, with a long finish. This wine is the essence of Sauvignon Blanc---no histrionics, no in-your-face flavors of gooseberry or whatever, just delicious, sappy, wine you want more of, with or without food. Hats off to everyone involved with this, from vineyard managers to winemakers to distributors and retailers: we need more wine like this!

Here's Bastianich's blog.

Physics and Song: Perimeter to U2 Tour 360, Rogers Centre, Toronto 9/16/2009, courtesy of Blackberry and/or Mike Lazaridis

Posted on by
1

Courtesy of Mike Lazaridis (CEO and co-founder of Research in Motion, the company that makes the Blackberry, and founder of Perimeter Institute, where I work), and/or his company (THANKS!!) the staff at Perimeter Institute was bused to Toronto and treated to the first of two U2 shows in the Rogers Centre, downtown next to the CN tower.  The roof was open on the arena, and those on the west side could see changing, glowing colors lighting up the elevator strip all the way up the CN tower, and encircling the observation deck. In my account of the concert below, I'll link to mostly YouTube videos to that give a play-by-play record of most of the concert---be warned that some of these are pretty low quality, though a few are surprisingly good.

Overall, the concert rocked.  Although I haven't followed U2 closely, I have a couple of their CDs from quite a while back---the excellent Achtung Baby, and a double live one, plus a few LPs kicking around that I haven't listened to recently.  They haven't lost their touch.  I particularly enjoyed some of the songs from their new album: the opening sequence "Breathe",  "Magnificent", and "Get on Your Boots".  My notes call the latter "surrealistic hard rock, with fuzz bass and Nirvana-y guitar riffs".  Its title and tacky-but-tasty riffs (think snarfing a box of Snyder's of Hanover Honey Mustard & Onion Pretzels) remind me of Sonic Youth's "Dirty Boots".   I liked the live "Boots" a bit better than the studio video version you can hear here--- a little grittier and harder-rocking.

Their traveling stage set (apparently one of three---the setup takes long enough that they need to start in one venue before the shows are finished in the next) is a giant pale-green thing, adorned with orange buttons and a tower sticking out the top, that looks like a cross between a giant four-legged beetle and the a lunar lander, and forms a tall canopy over the circular stage.  Under the belly of this thing, there's a huge circular video screen made of elongate hexagonal chunks, which can be interpreted as the thrust nozzle of a rocket engine.  Half-way through the show, the thing elongates vertically to more than twice its size, revealing that the screens are mounted on diagonally criss-crossing metal rods hinged to each other as in a folding set of coat-pegs, or wash-hanging rack.  It's used to show closeups of the performers, and various other graphics integral to the show.

We unfortuately missed the opening act, Snow Patrol, as the bus ride from Waterloo to Toronto is a lengthy proposition when you leave at 4 PM on a weekday.  The show started out with the bug thing towering over the empty stage as Bowie's "Space Oddity" was played on the sound system.  Then some moody, pretty music as the lights went out, the band came on, and the spots came up on them one by one, segueing into the band playing "Breathe" off their new album  (Here's longer, but better, video of the whole initial sequence from the last part of Space Oddity, through the band entrance and "Breathe").   Initially the sound balance left something to be desired---the low bass and kickdrum frequencies that resonate in your chest, and below, were overemphasized for my taste, while the actual low and low-midrange frequencies where the bass melody lives were underemphasized.  And the non-kickdrum parts of the drumset, especially at lower frequencies, were a bit undermixed too (partially remedied by Bono's call for "more drums" early in the set).  But basically the sound was pretty good, especially for an open arena which is probably pretty hard to fill sonically.  Vocals and guitar lines were pretty clear.  The band was able to carry things through Breathe and "No Line on the Horizon" as the sound settled down, or I stopped noticing it, and by Get On Your Boots things were rocking just fine.  (Here's some good video footage, with crummy no-bass sound, of the CN tower ... not sure this is actually "No Line" as claimed by the tuber who posted it, though.)  Here's the beginning of Magnificent (another song I liked from the new album, here's another snippet of it, and here's probably a better video of the whole song, from near the stage.)  This was followed by Get on Your Boots---no acceptable video from Toronto, so here it is from the opening show of the tour, in Barcelona's Olympic Stadium.  "Beautiful Day" from 2000's "All That You Can't Leave Behind" ended with a little snippet from Elvis Costello's "Alison", though with an somewhat altered, and I thought less interesting, melody.  "I Still Haven't Found What I'm Looking For" from Achtung Baby, here beginning with the audience doing a good bit of the singing, was the first of the oldies but goodies for me, followed by a nice version of Elevation (also from "All..."), with the band really getting into a disjointed but rocking groove appropriate to the somewhat "surrealistic" lyrics ("why can't the sun // shoot me from a gun..").  "Your Blue Room" was a classic, lazing-across-inner-space "orbit" song, at a meandering tempo with looping "satellite" motifs and footage shot from the International Space Station, and a little sprechstimme from Commander Frank.  Nice touch (as was the LEM-like stage-set)  in the anniversary year of the moon landing.  (Here it is from Chicago a few days earlier, from farther out so you can see the video display.) [Unknown Caller]  Until the End of the World resumes the sequence from Achtung Baby (begun with "Still Haven't Found...")  An even better video of End. Stay.  Unforgettable Fire (nice sound and video, but cut off after 2:50.  ).  This is when the rocket nozzle video screen got vertically elongated.  More good video of Unforgettable Fire; relatively decent sound for this kind of thing, but bass-challenged.  City of Blinding Lights.  Vertigo / Pump It Up.  Bono announced that Elvis was in the house; this, and the bit of Alison and Oliver's Army, were presumably in his honor.  (Some parts of this sound like Dirty Boots as well.)  I'll Go Crazy if I Don't Go Crazy Tonight (sound issues), a lightweight but hard-rocking pogo-ey, poppy bit of infectious fluff off the new album.  Another version of Crazy with different sound issues and funny audience vocal.  Sunday Bloody Sunday (OK sound, long view; late beginning).  Ends with a snippet of Elvis Costello's "Oliver's Army".  MLK, for Aung San Suu Kyi.  Walk On, and One, for Aung San Suu Kyi (seriously bad audience vocals from near whoever recorded this, but with some redeeming value (humor)).  Amazing Grace.  Where the Streets Have no Name.

Ultraviolet (Light My Way), another oldie but goodie from Achtung Baby.  Bono doesn't slack off when covering old songs...the phrasing is different in different performances, his heart and mind is in it.  With or Without You.  Moment of Surrender.

The Fresh and the Salt, or the Raw and the Cooked?---Krugman on how economics got it wrong...and Jonathan Richman on getting it straight.

Posted on by
Reply

OK, another must-link, to Paul Krugman's extended New York Times version of something he's blogged on before: the divide between "freshwater" and "saltwater" economists, and how the profession largely failed to anticipate the present economic crisis, and to some extent---especially in the "freshwater" camp---lacks the intellectual tools to deal with it.

Anybody who is interested in understanding the current economic situation, and in getting some background for their attempt to understand it, should read Krugman's article.  (And even more importantly, read Keynes' "General Theory".

As a graduate student in economics round about 1985-87, for a semester at Yale and then for two and a half years at Berkeley (I moved to the Bay Area for love), I got (or rather continued, since I'd taken a bit of econ as an undergrad, and done quite a bit of reading on my own) a squarely "saltwater" (this refers to the coastal US---say, Berkeley, Harvard, MIT, Yale---as opposed to the heartland---say, Minnesota and Chicago, and I'm not sure how far the generalization holds beyond these schools...) economics education, taking first-semester macro, for example, from Jim Tobin.  Yet even then, and there, we were subjected to readings from the "rational expectations" and "real business cycles" school of macro:  Barro, Sargent, Lucas.  I must admit I found this stuff as obviously out of touch with reality then, as Krugman is now telling us it is.  Often  fitted out with impressively technical talk of autocorrelations and regressions, it made claims such as:  systematic use of monetary policy to smooth out business cycles can't have any effect, because rational economic agents will anticipate it; business cycles are due to such "real" factors as shifts---due to underlying changes in "technological possibilities", not due to failure of aggregate demand---in the relative rewards to leisure versus labor, resulting in more people choosing leisure (the "Great Depresssion as Great Vacation" theory, as Krugman skewers it).   The apparently supportive econometric analyses apparently worked---I don't actually recall the econometric critiques of the time, having been more concerned at the time to acquire tools that would help me understand how the economy actually did function, than to score intellectual points against the wrong-headed---by mistaking correlation for causation, and leaving out of the analysis variables of critical importance.  Sometime somebody should---heck, somebody probably has, and I'd love to be pointed towards the analysis---take their macroeconometric work apart.  (Here's a contribution in that direction from one L. H. Summers---pretty devastating, I'd say.)

Krugman's article adduces two, or perhaps three reasons---the "beauty" of rational-agent equilibrium theories, the lure of "sabbaticals at the Hoover Institution and job opportunities on Wall Street" why "freshwater" macro gained as much influence as it did.  Of these, he thinks the "beauty" aspect was the more important.  I think a lengthy exploration of the culture and politics of the economics profession would reveal a lot about how the intertwining of politics, business, and academic culture enabled the rise of the freshwater school.  I'd love to see such a work, by an economically literate social scientist (perhaps even an economist).  Because to my mind, the fact that the bundle of misguided ideas Krugman is referring to as "freshwater economics" gained as much influence as it did, is a serious counterexample to the idea that economics, as practiced in the academy and the more academically-linked think-tanks and policymaking institutions, is a science that makes a serious effort to test its theories against reality, and judges the work of its practitioners accordingly.

Having said that, I'll admit to being very irritated by people who claim that economic theory and academic economics in general have been shown up as useless by the present crisis.  For me, Keynesian theory was always at the heart of macroeconomics, certainly the macro that was taught me when I was in grad school (and that I sought out to teach myself even before then) and its value as a tool to help understand and deal with reality is only accentuated by this slump---as is the value of intelligent, reasoned, reality-based economic analysis more generally.

Anyway, I'd like to think that "freshwater" versus "saltwater" may be a bit of a calumny on the heartland.  Maybe instead of the fresh versus the salt we should (reversing the order) call them, whether or not it fits with Levi-Strauss, the Raw and the Cooked, according to whether they are willing to accept the raw facts of economic slumps, unemployed resources, burst asset bubbles, or can't believe these are what they appear to be and (unintentionally in most cases, perhaps) are moved to cook the data via sophisticated regressions to fit their "markets can't fail" theories. For them, or those seduced by them, maybe the words of Jonathan Richman and the Modern Lovers (if you want to listen, the track was switched with "Modern World [alternate take]" ) are apropos, put into the mouth of a hypothetical bubble-acknowledging, behavioral-economics-friendly, neo-parti-Keynesian, reality-based "raw" economist:

Now I've watched you walk around here.
I've watched you meet these
boyfriends, I know, and you tell me how they're deep.
Look but, if these guys, if they're really so great,
tell me, why can't they at least take this place
and take it straight? Why always stoned,
like hippie Johnny is?
I'm straight and I want to take his place.

A spear carrier's view of the 1994 health care reform debacle (DeLong)

Posted on by
Reply

I get annoyed by blogs that are mostly just links to other people's stuff... but I had to link this great post from Brad DeLong on his inside view of the 1994 debacle in health care...

I"ve been wondering for the last few weeks or months... why can't Obama be more like LBJ?  Still, everyone has to operate from their own strengths... he may yet pull off health care reform in his own style, and for those who care about the horse-race aspect of this (and I certainly do inasmuch as it affects the Democrats' chances in the next two elections): by now, anything decent (or even apparently decent) by way of a health care bill will be viewed as a victory for Obama.

I'm worried, though, that although there are apparently European models for well-functioning healthcare that don't involve a public option, they involve nongovernmental nonprofit entities, or high levels of regulation.   Such models may be very difficult to replicate in this country where they may be easily co-opted or weakened by the money and influence big insurance can put behind things, and by the continual possibility of politically motivated medldling/sabotage.  Ironically, I fear our politics and culture may make a public option more workable than a semiprivate one.

Foundational Questions in the Azores I: Peter Byrne on Hugh Everett and Many Worlds

Posted on by
Reply

So far, there hasn't been much physics in Wine, Physics, and Song---nor much song, for that matter, though there's been plenty of wine, and some economics and politics.  I guess wine is easier and more relaxing to write about.  But it's time to redress that balance.

I arrived in Ponta Delgada, the main town of the island of São Miguel in the Portuguese archipelago of the Azores, courtesy of the Foundational Questions Institute, to attend and speak at their second annual conference.  We were treated to dinner and an after-dinner talk.  (The wines, especially a white called  something like Tierra de Lavas that was served before dinner, were tasty.)  The talk was by Peter Byrne, who is writing a biography of Hugh Everett III, the originator (unless you want to ascribe it to Schrödinger in his cat paper) of what he called the "relative state" interpretation of quantum mechanics, often called the "many worlds interpretation" (MWI).  I was particularly interested in this talk because a fascination with the problem of how to interpret quantum theory is a large part of what got me into physics.  In 1989--1990 I wrote a paper (unpublished), "The Many-Worlds Interpretation of Quantum Mechanics: Psychological versus Physical Bases for the Multiplicity of "Worlds", arguing that Everett's interpretation had often been misunderstood as involving a "physical" splitting of the universe into different branches, whereas Everett was actually fairly clear that the "branching" into parts of the universe involving different outcomes of a quantum experiment was associated with different subspaces of a single Hilbert space of the world, subspaces defined by which of the different macroscopic outcomes of the experiment an observer had experienced.  So I was very interested to hear from Peter Byrne that among the boxes of Everett's paper that he has been sorting and studying, were drafts of Everett's thesis in which there is much more extensive discussion of splitting minds than was available even in the long version of his thesis published by Princeton.  If I'm reporting Byrne correctly, one of these drafts compares the splitting minds to splitting amoebas, noting there is no fact of the matter as to which of the amoebas is the original one.  The whole thing, he says, had much more extensive discussion of splitting, which his advisor John Wheeler made him take out (partly, if I understood correctly, because of negative comments by Bohr, relayed by Stern who was on Everett's thesis committee).   It will be interesting to see the details of these drafts, and find out more about how Everett understood this "splitting".

My early paper was to some extent a "devil's advocate" exercise---I did not then, and do not now, believe in Everett's interpretation in the sense that a macroscopically entangled wavefunction, describing me having all kinds of different conscious experiences, is a real entity.  But I did believe, and still do, that pushing Everett's idea as far as possible is one good way of getting a better understanding of what is weird about quantum theory, and of the unexpected difficulties we've encountered in figuring out what quantum physics has to tell us about the world, and our place in it.

My reasons for not accepting many worlds are in part tied up with the fact that there don't seem to be probabilities of measurement outcomes on this interpretation, as there are indeed not definite classical outcomes.  More on this later---it is something that I've been thinking about for years, and before Byrne's talk, I had a long discussion about it with Alan Guth at dinner.   But one last thing:  it was therefore striking to hear from Byrne that one of a myriad of titles Everett considered for his dissertation was "Wave mechanics without probability".

Baco Viejo 2008 Chardonnay DO Central Valley

Posted on by
Reply

This inexpensive Chilean Chardonnay, which I drank at my parents' in DC recently, seems like great value---I believe they paid around $6 for it, but I'm not sure.  Some nice aromas and flavors something like peach and vanilla,  a rounded, balanced, even somewhat elegant feel in the mouth---not high-acid, but not flabby (or lush).   No overbearing oakiness--an excellent food wine.  Very drinkable, and somewhat reminiscent of Sonoma County's Chateau St. Jean Chardonnays---even their higher-end Robert Young Vineyard ones, which also have that low-acid, vanilla thing though more prominently, and (at least in the Robert Youngs) often with a velvetiness this lacks.   But velvetiness would not necessarily be an improvement.  This is crisper, a summer quaffer of a chardonnay but still quite flavorful and holding one's interest through a a meal---maybe not seriously complex, but far from one-dimensional.  Yum!  This is "produced and bottled by Viñas Errazuriz Ovalle, SA San Ignacio 2170 Santiago, Chile", and imported by Monsieur Touton, NYC; alas, I can't find a price or distributor reference with a cursory Google.  I do find some entertaining snark at Le Cheap Lush concerning Monsieur Touton, though---to which this wine would seem to be a counterexample, unless I was just in a particularly good mood when I drank it.

National Strategy Workshop on Quantum Information Science

Posted on by
Reply

Next week, I'll be at a workshop in Vienna, VA that has been organized to help come up with a national strategy for public investment in quantum information science and technology.

To quote from the workshop website:

This Workshop on Quantum Information Science (QIS) has been organized in response to the NSTC report. It brings together leading theorists and experimenters drawn from physical science, computer science, mathematics, and engineering who will assess recent progress in QIS and identify major goals and challenges for future research.

The report in question, titled "A Federal Vision for Quantum Information Science came out this January, from the US National Science and Technology Council which is part of the White House's Office of Science and Technology Policy.

All in all, a very interesting and promising development, which suggests serious potential for US government support for research in quantum information science, which is to say quantum computation, quantum computing, quantum cryptography, the use of quantum information science concepts to understand and engineer the behavior of complex physical systems, including quantum control and quantum metrology.  The report emphasizes computation and the understanding of new quantum states of matter and quantum phase transitions.  The organization appears to have been fairly rapid---probably carried out at Caltech, where John Preskill heads the Institute for Quantum Information, since that's where the website is located and the administrative coordinator is the IQI's.

The invited speaker lineup looks excellent, though some have complained that it's not representative of some aspects of quantum information research (metrology, i.e. precision quantum measurement, is covered only lightly) and some top US groups (like the quantum cryptography effort led by Richard Hughes at Los Alamos) are missing (though I don't know why).  Evenings will involve open discussions on strategy for QIS research, though I worry we may be burned out after full days of excellent technical presentations.

I'm looking forward to hearing Anne Broadbent talk about Universal Blind Quantum Computation with Joseph Fitzsimmons and Elham Kashefi, and not only because a crucial component of it is the use of quantum authentication codes, a concept developed my collaborators Claude Crepeau, Daniel Gottesman, Adam Smith, Alain Tapp, and me.  (Hey, this is my blog, so shameless self-promotion is de rigeur.)