quantum optics
drorzel | June 4, 2012In which we do a little ResearchBlogging, taking a look at a slightly confusing paper putting a new twist on the double-slit experiment.
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I'm off to California this afternoon, spending the rest of the week at DAMOP in Pasadena (not presenting this year, just hanging out to see the coolest new stuff in Atomic, Molecular, and Optical Physics). I don't want to leave the blog with just a cute-kid video for the whole week, though, so here's some had-core physics: a new paper in the Proceedings of the National Academy of Sciences (freely available online), looking at a new sort of…
drorzel | June 29, 2011The first of the five categories of active research at DAMOP that I described in yesterday's post is "Ultracold Matter." The starting point for this category of research is laser cooling to get a gas of atoms down to microkelvin temperatures (that is, a few millionths of a degree above absolute zero. Evaporative cooling can then be used to bring the atoms down to nanokelvin temperatures, reaching the regime of "quantum degeneracy." This is, very roughly speaking, the point where the quantum wavelength of the atoms becomes comparable to the spacing between atoms in the gas, at which point the…
drorzel | December 28, 2010It's the last week of the (calendar) year, which means it's a good time to recap the previous twelve months worth of scientific news. Typically, publications like Physics World will publish a list of top ten physics stories of 2010, but we're all Web 2.0 these days, so it seems more appropriate to put this to a poll:
What is the top physics story of 2010?survey software
I've used the Physics World list as a starting point, because you have to start somewhere. I added a few options to cover the possibility that they left something out, and, of course, you know where the comments are.
This…
drorzel | December 7, 2010Today is the official release date for the paperback edition of How to Teach Physics to Your Dog, so I wanted to write up something cool about quantum physics to mark the occasion. I looked around the house for inspiration, and most of what we have lying around the house is SteelyKid's toys. Thus, I will now explain the physics of quantum teleportation using SteelyKid's toys:
"Wait, wait, wait... You're not seriously planning to explain something quantum without me, are you?"
"I could hardly expect to get away with that, could I. No, I'm happy to have your contributions-- the book is about…
drorzel | November 19, 2010Earlier this week, I talked about the technical requirements for taking a picture of an interference pattern from two independent lasers, and mentioned in passing that a 1967 experiment by Pfleegor and Mandel had already shown the interference effect. Their experiment was clever enough to deserve the ResearchBlogging Q&A treatment, though, so here we go:
OK, so why is this really old experiment worth talking about? What did they do? They demonstrated interference between two completely independent lasers, showing that when they overlapped the beams, the overlap region contained a pattern…
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 24, 2010Two papers in one post this time out. One of these was brought to my attention by Joerg Heber, the other I was reminded of when checking some information for last week's mathematical post on photons. They fit extremely well together though, and both relate to the photon correlation stuff I was talking about last week.
OK, what's the deal with these? These are two papers, one recent Optics Express paper from a week or so ago, the other a Nature article from a few years back. The Nature paper includes the graph you see at right, which is a really nice dataset demonstrating the Hanbury Brown and…
drorzel | August 20, 2010In my post about how we know photons exist, I make reference to the famous Kimble, Dagenais, and Mandel experiment showing "anti-bunching" of photons emitted from an excited atom. They observed that the probability of recording a second detector "click" a very short time after the first was small. This is conclusive evidence that photons are real, and that light has discrete particle-like character. Or, as I said in that post:
This anti-bunching effect is something that cannot be explained using a classical picture of light as a wave. Using a wave model, in which light is emitted as a…
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 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 | July 30, 2010There's some good stuff in yesterday's post asking what physics you'd like to read more about. I'm nursing a sore neck and shoulder, so I'll only do one or two quick ones today, starting with James D. Miller in the first comment:
1) Is it true that our understanding of quantum physics comes from studying systems with only a small number of particles and there is a good chance our theories won't hold in more complex systems.
It all depends on how you define your terms-- what counts as a "small number" of particles, and what counts as not holding?
It's certainly true that most of the…
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 | 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…
drorzel | April 30, 2010We're just over 600 votes in the Laser Smackdown poll in honor of the 50th anniversary of the laser, as of early Friday morning. I notice that it has moved off the front page of the blog, though, so here's another signal-boosting repost, just so we have as many votes as possible, to establish maximum scientific validity when we declare the winner the Most Amazing Laser Application of All Time
Which of the following is the most amazing application of a laser?Market Research
Voting will remain open until next Sunday, May 2, just two days from now, with the ultimate winner announced on Monday…
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…