Quantum Optics
drorzel | February 2, 2010Congratulations to Alain Aspect, John Clauser, and Anton Zeilinger for winning the 2010 Wolf Prize in Phyiscs:
The 2010 Wolf Prize in Physics will be shared by Prof. John F. Clauser of the US; Prof. Alain Aspect of France's Ãcole Normale Supérieure de Cachan; and Prof. Anton Zeilinger of the University of Vienna. The jury in this field praised them "for their fundamental conceptual and experimental contributions to the foundations of quantum physics, specifically an increasingly sophisticated series of tests of Bell's inequalities, or extensions thereof, using entangled quantum states."
All…
drorzel | January 28, 2010Last week's Seven Essential Elements of Quantum Physics post sparked a fair bit of discussion, though most of it was at the expert level, well above the level of the intended audience. such is life in the physics blogosphere.
I think it's worth a little time to unpack some of the disagreement, though, as it sheds a little light on the process of writing this sort of thing for a general audience, and the eternal conflict between broad explanation and "dumbing down." And, if nothing else, it lets me put off grading the exams from last night for a little while longer.
So, what's the issue? The…
drorzel | January 26, 2010Way back in the early days of ScienceBlogs, I ran a competition of sorts to determine the greatest physics experiment in history. I collected a bunch of nominations, wrote up a post about each of the top 11 entries, and then asked people to vote for their favorite.
In honor of the 50th anniversary of the laser, let's take a stab at something similar:
What is the coolest thing you know of that's done with lasers?
Lasers are all over the place these days, from UPC scanners to telecom networks to optical drives to hospitals. All sorts of fascinating things have been done with lasers over the…
drorzel | January 25, 2010As mentioned previously, I've been reading Sean Carroll's Wheel arrow of time book, which necessarily includes a good bit of discussion of "Maxwell's Demon," a thought experiment famously proposed by James Clerk Maxwell as something that would allow you to cool a gas without obviously increasing entropy. The "demon" mans a trapdoor between a sample of gas and an initially empty space, and allows only slow-moving gas atoms to pass through. After some time, the empty volume is filled with a gas at lower temperature than the initial sample, while the gas in the original volume is hotter than…
drorzel | January 25, 20102010 marks the 50th anniversary of the invention of the laser. To mark the occasion, the American Physical society has launched LaserFest, which will involve a large number of public events over the next year. The website includes a bunch of cool things explaining the physics of lasers, and a timeline of laser history with one glaring bug that you'll have to figure out for yourself. Over at Cocktail Party Physics, Jennifer Ouellette has an excellent historical survey of her own, saving me a lot of typing.
(Fun fact: Gordon Gould, who eventually won a lengthy patent fight, was a Union alumnus…
drorzel | January 23, 2010That's the bill for the time that I spent on deciphering his supposed falsification of decoherence. I don't want anyone to fall for his false argument, so here's the correct explanation of the scenario, to save other people the trouble.
The center of his so-called "proof" is this modified Mach-Zehnder Inteferometer:
Light enters at the lower left, is split by a beamsplitter (which I'm representing as a beamsplitter cube, because that's what I usually use, but it could be anything), redirected by two mirrors to a second beamsplitter where the beams A and B are recombined, then the recombined…
drorzel | January 20, 2010The previous collection of things everyone should know about quantum physics is a little meta-- it's mostly talking up the importance and relevance of the theory, and not so much about the specifics of the theory. Here's a list of essential elements of quantum physics that everyone ought to know, at least in broad outlines:
1) Particles are waves, and vice versa. Quantum physics tells us that every object in the universe has both particle-like and wave-like properties. It's not that everything is really waves, and just sometimes looks like particles, or that everything is made of particles…
drorzel | January 20, 2010Derek Lowe has a post talking about things biologists should know about medicinal chemistry. It's a good idea for a post topic, so I'm going to steal it. Not to talk about medicinal chemistry, or biologists, of course, but to talk about my own field, and what everyone-- not just scientists-- should know about quantum physics. Not just humans, either-- even dogs should know this stuff.
1) Quantum physics is real. Probably the hardest quantum idea to accept is the notion of vacuum energy and "virtual particles"-- stuff appearing out of empty space, then disappearing again seems almost too weird…
drorzel | January 12, 2010I'm standing in the kitchen, sipping tea and watching snow blowing across the back yard. It's cold enough that the digital thermometer has stopped working, which puts it in the single digits Fahrenheit. I'm not looking forward to walking the dog in this.
"Pretty cold, dude," she says.
"Yeah," I say. "It's cold, all right."
"You better let me outside," she says, tail wagging. "I'm gonna catch a whole bunch of bunnies!"
"A whole bunch? How do you figure?"
"Well, it's so cold that they'll all be together. You know, like one of those Bozo Condensates."
"Bozo Condensate?" It's too early in…
drorzel | January 11, 2010I was looking at some polling about science over the weekend, and discovered that they helpfully provide an online quiz consisting of the factual questions asked of the general public as part of the survey. Amusingly, one of them is actually more difficult to answer correctly if you know a lot about the field than if you only know a little. I'll reproduce it here first, if you would like to take a crack at it, and then I'll explain why it's tricky below the fold.
The global positioning system, or GPS, relies on which of these to work?(answers)
Choose only one answer-- this is being recorded…
drorzel | January 5, 2010"Slow light" is in the news again. The popular descriptions of the process usually leave a lot to be desired, so let's see if we can't do a slightly better job of explaining what's going on. The key idea is using one light beam to control the transmission of another.
Let's say you have a bunch of atoms in a gas and a laser. The laser happens to be at exactly the right frequency to be absorbed by the atoms, meaning that if you try to shine the laser through the gas, it'll be absorbed, and won't make it out the other side. This is traditionally represented by a diagram like to one to the right…
drorzel | December 18, 2009How to Teach Physics to Your Dog is now listed as "In Stock" at Amazon, so it's the perfect time to order a dozen or so copies for your last-minute holiday gift needs.
"But, wait," you say, "why do I want to teach my dog physics? Particularly quantum physics-- why does anyone need to know that?"
The answer is: "Lasers." Lasers are pretty awesome, right? Let's ask an expert:
If I were creating the world I wouldn't mess about with butterflies and daffodils. I would have started with lasers, eight o'clock, Day One!
OK, maybe he's a bad one to ask. Still, lasers are pretty awesome, and lasers…
drorzel | December 17, 2009Yesterday's reason to love quantum was the CCD sensor, which relies on the photoelectric effect to take digital pictures. Sticking with the photoelectric theme, today's first quantum-enabled technology is the photovoltaic cell, the basis for solar panels.
Photovoltaic cells convert light into electricity, essentially via the same photoelectric effect used in CCD's. A photon of light comes along, and knocks an electron out of some material (typically something silicon-based), and that electron is used to create a current that can power electrical devices. There's some tricky business involved…
drorzel | December 16, 2009I've been writing a bunch of publicity copy for the book the last few weeks, and one of those things is a list of reasons why every dog should know about quantum physics. I've been planning to chop that up into a bunch of individual blog posts in the run-up to the book, but the Washington Post beat me to (one of) the punch(es):
Getting a digital camera for Christmas? Before you fire it up to capture Uncle Wally's fateful fifth trip to the punch bowl, take a moment to picture this: You've got a genuine scientific marvel in your mitts. In fact, it took nothing less than two Nobel prizes and a…
drorzel | December 16, 2009While I'm thrilled to see How to Teach Physics to Your Dog listed on Amazon, I am distressed to see it offered as a pair with something called The Intention Experiment by Lynne McTaggart. I'm not linking to the Amazon page for that book, because it's a giant pile of crap, and I wouldn't want anyone to accidentally one-click-order it after following a link from my page.
If you should choose to look it up, you can read bits and pieces of it via the "Look Inside" feature, and it's true that the opening chapter or so is a reasonable-sounding description of the physics of quantum entanglement,…
drorzel | December 15, 2009It's exactly one week to the release date for How to Teach Physics to Your Dog, and to celebrate, I'm setting off on an expedition to the local mall(s) in search of Christmas presents. May God have mercy on my soul...
Anyway, I wouldn't want you to be without entertainment while I'm off helping the economy, so here's another little video to mark the one-week anniversary. This one is the dog dialogue from Chapter 5, on the quantum Zeno effect, and while it doesn't have puppets, it does feature some happy dog video, before settling down into still pictures and graphics:
We're at the point, now…
drorzel | December 11, 2009One of the things I forgot to mention in yesterday's post about why I like AMO physics is that AMO systems have proven to be outstanding tools for solving problems from other fields of physics. In particular, ultra-cold atoms have proven to be a fantastic venue for studying problems from condensed matter physics. There's a comprehensive review of the subject in this Reviews of Modern Physics paper, which is also freely available on the arxiv. I say "comprehensive review," but, of course, it's almost certainly already out of date, given how much work is going on in this area.
To understand why…
drorzel | December 10, 2009Months ago, during the DonorsChoose fundraiser, I offered to answer questions from people who donated to the Challenge. I then promptly forgot to respond to the questions sent in. Mea maxima culpa. Here's a way-too-late response to a good question from "tcmJOE":
I've spent the past few years trying to explore physics and figure out what I would be interested in doing--I've settled more towards energy research, somewhere between CM and MatSci, but I've tried at a variety of different things in the along the way. So my question for you is: How did you end up in AMO? Were there any other fields…
drorzel | December 2, 2009I've made a couple of oblique references to this over the past couple of months, but I have an article in the new issue of Physics World, on experiments using molecules to search for an electric dipole moment of the electron:
When most of us think about searching for physics beyond the Standard Model - the dominant paradigm of particle physics - the first thing that springs to mind is probably a gigantic particle accelerator like CERN's Large Hadron Collider (LHC). Within the collider's 27-km loop, protons slam together at 99.9999991% of the speed of light. Office-building-sized detectors…
drorzel | November 24, 2009The official release date for How to Teach Physics to Your Dog is exactly four weeks from today. So here's a dramatic reading of Chapter 3 to mark the occasion:
I've put this up before, but I edited it to remove the URL, which was apparently a deal-breaker for booksellers. And yes, I will post about something other than the book, Real Soon Now...