Condensed Matter

Category archives for Condensed Matter

Two papers with a similar theme crossed my social media feeds in the last couple of days. You might think this is just a weird coincidence, but I’m choosing to take it as a sign to write about them for the blog. So, what are these papers, and what’s the theme? One is the final…

As noted in a previous post on Monte Carlo simulation in 1960, we recently came into possession of a large box of old Master’s theses. The bulk of these are from the 50’s and 60’s, but there are some going back much farther. As I pass these every day I’m in the office, I thought…

When Is a Composite Object a Particle?

Through some kind of weird synchronicity, the title question came up twice yesterday, once in a comment to my TED@NYC talk post, and the second time on Twitter, in a conversation with a person whose account is protected, thus rendering it un-link-able. Trust me. The question is one of those things that you don’t necessarily…

Last time in our trip through the cold-atom toolbox, we talked about light shifts, where the interaction with a laser changes the internal energy states of an atom in a way that can produce forces on those atoms. This allows the creation of “dipole traps” where cold atoms are held in the focus of a…

The Making of a Sign Error

One thing I left out of the making-of story about the squeezed state BEC paper last week happened a while after publication– a few months to a year later. I don’t quite recall when it was– I vaguely think I was still at Yale, but I could be misremembering. It’s kind of amusing, in an…

Yesterday’s write-up of my Science paper ended with a vague promise to deal some inside information about the experiment. So, here are some anecdotes that you would need to have been at Yale in 1999-2000 to pick up. We’ll stick with the Q&A format for this, because why not? Why don’t we start with some…

Hey, dude? Yeah, what’s up? I’m not normally the one who initiates this, but I was wondering: When you were at DAMOP last week, did you see any really neat physics? Oh, sure, tons of stuff. It was a little thinner than some past meetings– a lot of the Usual Suspects didn’t make the trip–…

Last week’s post talked about the general idea of negative temperature, with reference to this much-talked-about Science paper (which also comes in a free arxiv version from which the figures used here are taken). I didn’t go into the details of how they made a negative temperature gas, though, and as it’s both very clever…

The most talked-about physics paper last week was probably Negative Absolute Temperature for Motional Degrees of Freedom (that link goes to the paywalled journal; there’s also a free arxiv preprint from which the above figure is taken). It’s a catchy but easily misinterpreted title– Negative absolute temperature! Below Absolute Zero! Thermodynamics is wrong!– that obscures…

The “Ballistic” Story

Last week, in the post about fermion conduction, I left a reference hanging: There’s nothing physically blocking the atoms from flying right through the channel– in fact, an atom that enters the channel will always exit the other side without slowing down along the way. This is termed “ballistic,” a term that will always have…