quantum
drorzel | October 2, 2010A quick check-in from Tuscaloosa, where we're getting ready to head out for the football tailgating. While I've got a minute, though, here are the slides from my public lecture, via SlideShare:
What Every Dog Should Know About Quantum Physics
View more presentations from Chad Orzel.
These are probably less comprehensible that some of my other talks, as I deliberately avoided putting much text on the slides, which I think works better for this kind of presentation. The down side, of course, is that it's not as obvious what some of the slides mean, if you don't know the intended flow of the…
drorzel | September 7, 2010In chapter 2 of How to Teach Physics to Your Dog, there's a footnote about the ubiquity of uncertainty principle analogies in the mass media:
To give you an idea of the breadth of subjects in which this shows up, in June 2008, Google turned up citations of the Heisenberg Uncertainty Principle in (among others) an article from the Vermont Free Press about traffic cameras, a Toronto Star article citing the influence of YouTube on underground artists, and a blog article about the Phoenix Suns of the NBA. Incidentally, all of these articles also use the Uncertainty Principle incorrectly--by the…
drorzel | August 31, 2010A lot of people have been blogging and Twittering about this subway map of science, which puts various branches of science in the place of the lines on the London Underground map, showing connections between them. It's a huge graphic, but a kind of cool image.
I do, however, have a problem with it, which is illustrated by the key to the lines shown at right. The category of physics is presented as "Theoretical Physics and Quantum Mechanics." I have no problem with the quantum part, as quantum mechanics is one of the greatest intellectual achievements in human history. I do have a problem…
drorzel | August 30, 2010Last week, John Baez posted a report on a seminar by Dzimitry Matsukevich on ion trap quantum information issues. In the middle of this, he writes:
Once our molecular ions are cold, how can we get them into specific desired states? Use a mode locked pulsed laser to drive stimulated Raman transitions.
Huh? As far as I can tell, this means "blast our molecular ion with an extremely brief pulse of light: it can then absorb a photon and emit a photon of a different energy, while itself jumping to a state of higher or lower energy."
I saw this, and said "Hey, that's a good topic for a blog post…
drorzel | August 18, 2010Most of the time, when we talk about seeing quantum effects from light, we talk about extremely weak beams-- looking at intensities where one photon more or less represents a significant change in the intensity of the light. Last week, though, Physics Buzz wrote up a paper that goes in the other direction: they suggest a limit on the maximum strength of a laser pulse due to quantum effects, specifically the creation of particle-antiparticle pairs.
This is a little unusual, in that most of the time when people talk about really intense lasers, they end up discussing them as an oscillating…
drorzel | August 10, 2010A reader emails to ask about a new-to-me theory of physics, called "Quantum Space Theory" being promoted by a fellow named Thad Roberts. I wouldn't usually bother with this, but Roberts was one of the speakers at TEDx Boulder. this is disappointing, to put it mildly-- TED is a respected organization, and I don't like seeing them lend their support to something that is just dripping with kook signifiers. The key paragraph of the overview of the theory is:
To start grasping this higher-dimensional intuÂitive picÂture check out the book excerpts in the book excerpts secÂtion. If you are more…
drorzel | August 6, 2010In comments to yesterday's post about my favorite Many-Worlds story, a couple of people mention "All the Myriad Ways," a Larry Niven short story. I don't think I've ever actually read the story, but it gets brought up all the time, so I'm familiar with the concept. It's an angle on Many-Worlds that I don't like, and has something in common with the central conceit of Inception, which is also not high on my list of literary tropes, though my reaction isn't anywhere near as negative as Scott's.
If you're not familiar with it, here's the summary from Wikipedia:
A police detective, pondering a…
drorzel | August 5, 2010Today, Tor.com has posted the complete story "Divided by Infinity" by Robert Charles Wilson. This remains probably the best science fiction story ever using the Many-Worlds interpretation of quantum physics (though it doesn't call it that explicitly), and also the creepiest:
In the year after Lorraine's death I contemplated suicide six times. Contemplated it seriously, I mean: six times sat with the fat bottle of Clonazepam within reaching distance, six times failed to reach for it, betrayed by some instinct for life or disgusted by my own weakness.
I can't say I wish I had succeeded,…
drorzel | August 5, 2010A reader emailed me with a few questions regarding How to Teach Physics to Your Dog, one of which is too good not to turn into a blog post:
What is a photon from an experimental perspective?... Could you perhaps provide me with a reference that discusses some experiments and these definitional issues?
The short form of the experimental answer is "A photon is the smallest amount of light that will cause a detector to 'click.'" (For some reason, hypothetical light detector technology has never really advanced past the Geiger counter stage-- even though it's all electrical pulses these days, we…
drorzel | August 2, 2010Thoreau at Unqualified Offerings gets credit for inspiring two posts today with his proposed Murphy's Law experiment and this one, about an unrelated issue in quantum measurement. This is an analogy suggested by a colleague a couple of years ago, comparing the projection of a quantum wavefunction in the measurement process to the lottery.
The classic example of this problem is something like the double slit experiment with single particles. You have some position-sensitive detector that we can imagine as being made up of a large number of pixels, each having some probability of detecting a…
drorzel | July 27, 2010When one of the most recent issues of Physical Review Letters hit my inbox, I immediately flagged these two papers as something to write up for ResearchBlogging. This I looked at the accompanying viewpoint in Physics, and discovered that Chris Westbrook already did most of the work for me. And, as a bonus, you can get free PDF's of the two articles from the Physics link, in case you want to follow along at home.
Since I spent a little time thinking about these already, though, and because it connects to the question of electron spin that I talked about yesterday, I think it's still worth…
drorzel | July 23, 2010This week's big story in physics is this Science paper by a group out of Austria Canada (edited to fix my misreading of the author affiliations), on a triple-slit interference effect. This has drawn both the usual news stories and also some complaining about badly-worded news stories. So, what's the deal?
What did they do in this paper? The paper reports on an experiment in which they looked at the interference of light sent through a set of three small slits, and verified that the resulting pattern agrees with the predictions of the Born rule for quantum probabilities.
What does Matt Damon…
drorzel | June 23, 2010I don't remember who pointed me at this transcript of Deepak Chopra interviewing Michio Kaku, but if I remember who it was, I fully intend to hate them.
DC: Is our conversation affecting something in another galaxy right now?
MK: In principle. What we're talking about right is affecting another galaxy far, far beyond the Milky Way Galaxy. Now when the Big Bang took place we think that most of the matter probably was vibrating in unison.
DC: So it was already correlated?
MK: It was already correlated. We call this coherence or correlation. As the universe expanded, we're still correlated, we'…
drorzel | May 13, 2010I get asked my opinion of Bohmian mechanics a fair bit, despite the fact that I know very little about it. This came up again recently, so I got some suggested reading from Matt Leifer, on the grounds that I ought to learn something about it if I'm going to keep being asked about it. One of his links led to the Bohmian Mechanics collaboration, where they helpfully provide a page of pre-prints that you can download. Among these was a link to the Bohmian Mechanics entry in the Stanford Encyclopedia of Philosophy, which seemed like a good place to start as it would be a) free, and b) aimed at a…
drorzel | May 3, 2010Voting has closed on the Laser Smackdown poll, with 772 people recording their opinion on the most amazing of the many things that have been done with lasers in the fifty years since the invention of the first working laser (see the Laserfest web site for more on the history and applications of lasers). The candidates in the traditional suspense-building reverse order:
Lunar laser ranging 22 votes
Cat toy/ dog toy/ laser light show 41 votes
Laser guide stars/ adaptive optics 46 votes
Holography 47 votes
Laser eye surgery 53 votes
Optical storage media (CD/DVD/Blu-Ray) 60 votes
Laser frequency…
drorzel | April 21, 2010What's the application? An optical frequency comb is a short-duration pulsed laser whose output can be viewed as a regularly spaced series of different frequencies. If the pulses are short enough, this can span the entire visible spectrum, giving a "comb" of colored lines on a traditional spectrometer. This can be used for a wide variety of applications, from precision time standards to molecular spectroscopy to astronomy.
What problem(s) is it the solution to? 1) "How do I compare this optical frequency standard to a microwave frequency standard?" 2) "How do I calibrate my spectrometer well…
drorzel | April 8, 2010Via Twitter, Michael Barton is looking for some good books about physics. I was Twitter-less for a few days around the period of his request, and this is a more-than-140-characters topic if ever there was one, so I'm turning it into a blog post.
The reason for the request is that he's going to be working as an intern at the Einstein exhibit when it visits Portland, which makes this a little tricky, as relativity is not an area I've read a lot of popular books in (yet-- that's changing). That will make this a little more sparse than it might be in some other fields.
There's also an essential…
drorzel | March 22, 2010I gave a talk today for a group of local home-school students and parents, on the essential elements of quantum physics. The idea was to give them a sense of what sets quantum mechanics apart from other theories of physics, and why it's a weird and wonderful thing.
The title is, of course, a reference to How to Teach Physics to Your Dog, and the second slide was an embedded version of the Chapter 3 reading. I set the talk up to build toward the double-slit experiment with electrons, using the video of the experiment made by Hitachi. Here's the talk on SlideShare:
What Every Dog Should Know…
bioephemera | March 19, 2010A slight science journalism FAIL in a story at iO9, originally from the New Scientist:
the Title: "First Quantum Effects Seen in Visible Object"
the Lede: "Does Schrödinger's cat really exist? You bet. The first ever quantum superposition in an object visible to the naked eye has been observed."
the Discovery: "[researchers showed] that a tiny resonating strip of metal - only 60 micrometres long, but big enough to be seen without a microscope - can both oscillate and not oscillate at the same time."
the Wait, what?: "Alas, you couldn't actually see the effect happening, because that very act…
pontiff | March 12, 2010The APS March meeting is next week as 10000 physicists invade Portland, Oregon. I hope Powell's bookstore has stocked their science sections well! GQI, the topical group on quantum information, sponsors a good number of sessions at the meeting including sessions with invited talks, focus sessions, and general sessions. Below the fold I'm assembling a list of quantum computing sessions, but before the fold I'd like to point out the invited sessions, which have longer speaking slots where one can actually learn more than the speakers name and research project title, that are sponsored or…