In 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… Continue reading Why Antibunching Equals Photons
Category: Optics
Quantum Optics from the Opposite Direction: QED Limits on Laser Intensities
Most 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… Continue reading Quantum Optics from the Opposite Direction: QED Limits on Laser Intensities
Do Not Look In Laser Pointer With Remaining Eye
Some folks I used to work with at NIST have looked at cheap green laser pointers, and found a potential danger. Some of the dimmer-looking green lasers are not so dim in the infrared, and in one case emitted 10X the rated power in invisible light. This could be a potential eye hazard. You can… Continue reading Do Not Look In Laser Pointer With Remaining Eye
What Do You Need to Make Cold Atoms? Part 2: Lasers and Optics
Following on yesterday’s discussion of the vacuum hardware needed for cooling atoms, let’s talk about the other main component of the apparatus: the optical system. The primary technique used for making cold atoms is laser cooling, and I’m sure it will come as no surprise that this requires lasers, and where there are lasers, there… Continue reading What Do You Need to Make Cold Atoms? Part 2: Lasers and Optics
Quantum Mechanics Is Square: “Ruling Out Multi-Order Interference in Quantum Mechanics”
This 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… Continue reading Quantum Mechanics Is Square: “Ruling Out Multi-Order Interference in Quantum Mechanics”
Photons: Still Bosons
Last week, Dmitry Budker’s group at Berkeley published a paper in Physical Review Letters (also free on the arxiv) with the somewhat drab title “Spectroscopic Test of Bose-Einsten Statistics for Photons.” Honestly, I probably wouldn’t’ve noticed it, even though this is the sort of precision AMO test of physics that I love, had it not… Continue reading Photons: Still Bosons
Watching Individual Atoms Make a Phase Transition
A press release from Harvard caught my eye last week, announcing results from Markus Greiner’s group that were, according to the release, published in Science. The press release seems to have gotten the date wrong, though– the article didn’t appear in Science last week. It is, however, available on the arxiv, so you get the… Continue reading Watching Individual Atoms Make a Phase Transition
The Limits of Rohirrim Vision
Over at Tor.com, Kate has a Lord of the Rings re-read post about the Battle of the Pelennor Fields, which includes a shout-out to me that I missed because I was driving to NYC: Ãomer is “scarely a mile” away when the standard unfurls and is clearly seen to bear the White Tree, Seven Stars,… Continue reading The Limits of Rohirrim Vision
Table-Top X-Ray Lasers
I mentioned in a previous post that one of the cool talks I saw at DAMOP had to do with generation of coherent X-Ray beams using ultra-fast lasers. What’s particualrly cool about this work is that it doesn’t require gigantic accelerators or nuclear explosions to produce a laser-like beam of x-rays– it’s all done with… Continue reading Table-Top X-Ray Lasers
Relativity on a Human Scale
While I mostly restricted myself to watching invited talks at DAMOP last week, I did check out a few ten-minute talks, one of which ended up being just about the coolest thing I saw at the meeting. Specifically, the Friday afternoon talk on observing relativity with atomic clocks by Chin-Wen Chou of the Time and… Continue reading Relativity on a Human Scale