quantum
pontiff | May 29, 2009Recently I finally got a chance to read the new preprint arXiv:0905.2292 "A new physical principle: Information Causality" by M. Pawlowski, T. Paterek, D. Kaszlikowski, V. Scarani, A. Winter, and M. Zukowski. It's been a long time since I spent more than a few spare hours thinking about foundational issues in quantum theory. Personally I am very fond of approaches to foundational questions which have a information theoretic or computational bent (on my desktop I have a pdf of William Wootter's thesis "The Acquisition of Information From Quantum Measurements" which I consider a classic in…
rallain | April 21, 2009I am not sure if First Excited State posted this as a blog entry, but it was mentioned on twitter. Question: why are sparks blue? My first gut response was that this is the blackbody color. Wrong for several reasons. The short answer is that sparks are blue because of the colors given off from nitrogen and oxygen when they are excited.
In order to make this post longer than necessary, let me say something about blackbodies. A blackbody is an object that emits radiation due only to it's temperature. Since it does not reflect anything, it looks black at room temperatures. You can make a…
rallain | March 6, 2009Temperature is a pretty weird thing if you think about it. How do you best define temperature? Let me go ahead and give you my favorite definition:
Temperature is the thing that two objects have in common when they have been in contact for a long time.
Yes, that is a good definition. Maybe now you can see why temperature is weird. Doesn't it have something to do with energy? Well, something - yes. Let me take an example. Suppose pour some hot coffee into a paper cup (I use paper because styrofoam(TM) is trademarked). Further suppose that this is super hot coffee from McDonald's. Can…
rallain | February 24, 2009Quantum mechanics is not my area of expertise. Really, I have no area of expertise. However, I think it is time to bring the whole photon thing back up. Yes, I know I was a little harsh before. Maybe I should start over.
First, models. Yes models. I think science is all about models. Scientists build models that attempt to agree with observations. These models could be mathematical, physical, conceptual or numerical (like a computer program). For example, take Newton's Law of gravity (which isn't really a law). It says that the gravitational force between two objects has the…
pontiff | February 17, 2009I like poker and I like quantum computing and lo and behold here is a paper with both:arXiv: 0902.2196Title: Quantized PokerAuthors: Steven A. Bleiler
Poker has become a popular pastime all over the world. At any given moment one can find tens, if not hundreds, of thousands of players playing poker via their computers on the major on-line gaming sites. Indeed, according to the Vancouver, B.C. based pokerpulse.com estimates, more than 190 million US dollars daily is bet in on-line poker rooms. But communication and computation are changing as the relentless application of Moore's Law…
pontiff | February 8, 2009In a prior post I asked about the how the structure of fixed points of stochastic maps changes under composition of such maps. Robin provided an interesting comment about the setup, linking this question at least partially with zero error codes:
R has at least one fixed point. If it's unique, there need be no relationship between fixed points of P and R. (Q can project to a single vector, which becomes the unique fixed point of R.) If R has N > 1 fixed points, then things get more interesting. The fixed points are closed under linear combination, so they're a subspace (I'm actually…
pontiff | February 5, 2009I've never made it to Benasque, and am always profoundly jealous of those who have gone:Dear Colleague,
We are pleased to inform you that following a very successful editions of Benasque 1998, 2000, 2003, 2005, and 2007, we are organizing another workshop of the similar type in June 2009. This is to invite you to apply using the electronic form that you can find on the website specified below. We encourage you to apply as soon as possible and not later than the end of March 2009. The number of participants at the Benasque Centre at any given time is limited to about 50. We will do our best to…
pontiff | February 3, 2009Sir Tobias Osborne of the Quantum Boolean Functions has made the plunge and is trying out open notebook science: Tobias J. Osborne's Research Notes.
Which reminded me of some dream software I've been thinking of writing (oh Time you Devil---why could you not expand to fit in all I want to create and do in this life!)
The basic idea is as follows. Blogs are great for a few reasons. One is they provide a journal system and date stamping system. Second they allow for commenting and this commenting can be done after some basic user authentication. But they are, it seems to me, not ideal…
pontiff | January 16, 2009The Perimeter Scholars Institute is a Masters level course designed to prepare students for cutting-edge research in theoretical physics. It looks pretty cool with some outstanding lecturers. The application deadline is February 1. All accepted students will be fully supported. Details below the fold.
Perimeter Institute for Theoretical Physics (PI) is a leading international research centre whose goal is to catalyze breakthroughs in our understanding of the physical world. PI strives to create a lively and dynamic research atmosphere where many approaches to fundamental questions, both…
drorzel | January 12, 2009 There's been a fair bit of press for the article Subtracting photons from arbitrary light fields: experimental test of coherent state invariance by single-photon annihilation, published last month in the New Journal of Physics, much of it in roughly the same form as the news story in Physics World (which is published by the same organization that runs the journal), which leads with:
A property of laser light first predicted in 1963 by the future Nobel laureate Roy Glauber has been verified by physicists in Italy.
These stories can be a little puzzling, though. After all, Glauber got his…
drorzel | December 10, 2008I'm a little cranky after a day of reviewing grant proposals, so it's possible that I'm overreacting. But commenter Neil B has been banging on about quantum measurement for weeks, including not one, not two, but three lengthy comments in Tuesday's dog post.
For that reason, I am declaring this post's comments section to be the Official Neil B. Quantum Measurement Thread. Until such time as I declare the subject open again, this is the only thread in which I want to see comments about quantum measurement. Attempts to bring the subject up in comments to other posts-- even other posts having to…
drorzel | December 8, 2008I made a run to the library last week on one of the days I was home with SteelyKid, as an excuse to get out of the house for a little while. I picked up three books: Counterknowledge, The Devil's Eye by Jack McDevitt (an Antiquities Dealers Innnnn Spaaaaaace novel, and a good example of Competence Fiction), and a pop-science book titled The Age of Entanglement: When Quantum Physics Came of Age by Louisa Gilder, because it looked fairly relevant to my own book-in-progress.
Amusingly, my RSS feeds yesterday brought me the latest in a series of posts in which ZapperZ waxes peevish about the book…
rallain | November 11, 2008[In part I of this post](http://scienceblogs.com/dotphysics/2008/11/interaction-between-light-an…), I struggled to show that a particle in an infinite well can only exist at certain energies. If you try to put a particle with more than one energy, the probability oscillates at a frequency (E2 - E1)/h. So, what is next? Well I think I am ready to attack the photon.
According to the ultimate source of truthiness (wikipedia), [the photon is the elementary particle responsible for the electromagnetic interaction](http://en.wikipedia.org/wiki/Photon). In general, the photon is view as the…
rallain | November 11, 2008One of the fundamental aspects of physics is the study of light and how that interacts with matter. I have been putting off this post - mainly because I am not a quantum mechanic (I am a classical mechanic). There are lots of things that could be done in this post, but I am going to try and keep it limited (and maybe come back to the interesting points later). Also, most of my posts are aimed at the intro-college level or advanced high school level. This will be a little higher. If you are in high school, there is still a lot of stuff for you here.
Let me summarize where I am going to…
pontiff | October 10, 2008From the annals of strangely mixed news stories. Canada: $25 billion government bailout and....$50 million for the University of Waterloo's Institute for Quantum Computing:BRANTFORD, Ont. -- The $25-billion government deal to buy mortgages from Canada's banks isn't a lifeline for lenders stuck with bum loans, Prime Minister Stephen Harper said Friday...
He said the government will likely make money on the deal, because its borrowing costs are lower than those available to banks.
Harper also produced an election goodie, promising a $50-million grant to a high-tech research lab at the…
pontiff | September 30, 2008Two quantum postdoc advertisements crossed my desk this week, from two fine institutions. Good postdocs if you can land one! The first advertisement is a double wammy from CaltechCENTER FOR THE PHYSICS OF INFORMATION
CALIFORNIA INSTITUTE OF TECHNOLOGY
Postdoctoral Research Positions
The Center for the Physics of Information at the California Institute of
Technology will have postdoctoral scholar positions available beginning
in September 2009. Researchers interested in all aspects of the
interface between information science and physical science are invited
to apply. The appointment is…
pontiff | September 30, 2008The New York Times has an article about Chongo Chuck. Chongo is a legendary homeless rock climber who lived in Yosemite for years. He is also the author of The Homeless Interpretation of Quantum Mechanics. Anyone ever seen a copy?
pontiff | August 4, 2008Michael Nielsen has a nice essay up explaining Why the world needs quantum mechanics:Conventional wisdom holds that quantum mechanics is hard to learn. This is more or less correct, although often overstated. However, the necessity of abandoning conventional ways of thinking about the world, and finding a radically new way - quantum mechanics - can be understood by any intelligent person willing to spend some time concentrating hard. Conveying that understanding is the purpose of this essay.
For a good explanation of Bell inequalities, jump to Michael's essay.
At the end of the article,…
pontiff | August 1, 2008A result of much quantum coolness out today: arXiv:0807.4935 (scirate): "Quantum Communication With Zero-Capacity Channels" by Graeme Smith and Jon Yard. Strange things they are going on when we try to use our quantum cell phones, it seems. Quantum cell phones, what the hell? Read on...
You know the situation. You're standing in line to get your morning coffee and bagel, and you get a call from your boss: "Hey Pontiff Dude, what's your bank account number? I need to have it so that I can deposit this large bonus into your account and if I don't do this within a few seconds, you won't get…