How Does Light Travel Through Glass?

I’ve mentioned before that I’m answering the occasional question over at the Physics Stack Exchange site, a crowd-sourced physics Q&A. When I’m particularly pleased with a question and answer, I’ll be promoting them over here like, well, now. Yesterday, somebody posted this question: Consider a single photon (λ=532 nm) traveling through a plate of perfect […]

Why Antibunching Equals Photons

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 […]

What’s a Photon, and How Do We Know they Exist?

A 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 […]

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 […]

Entanglement Happens

There have been a bunch of stories recently talking about quantum effects at room temperature– one, about coherent transport in photosynthesis , even escaped the science blogosphere. They’ve mostly said similar things, but Thursday’s ArxivBlog entry had a particular description of a paper about entanglement effects that is worth unpacking: Entanglement is a strange and […]