Friday, September 23, 2016

Nanovation podcast

 Michael Filler is a chemical engineering professor at Georgia Tech, developing new and interesting nanomaterials.  He is also the host of the outstanding Nanovation podcast, a very fun and informative approach to public outreach and science communication - much more interesting than blogging :-) .  I was fortunate enough to be a guest on his podcast a couple of weeks ago - here is the link.  It was really enjoyable, and I hope you have a chance to listen, if not to that one, then to some of the other discussions.

Wednesday, September 21, 2016

Deborah Jin - gone way too soon.

As was pointed out by a commenter on my previous post, and mentioned here by ZapperZ, atomic physicist Deborah Jin passed away last week from cancer at 47.   I don't think I ever met Prof. Jin (though she graduated from my alma mater when I was a freshman) face to face, and I'm not by any means an expert in her subdiscipline, but I will do my best to give an overview of some of her scientific legacy.  There is a sad shortage of atomic physics blogs....  I'm sure I'm missing things - please fill in additional information in the comments if you like.

The advent of optical trapping and laser cooling (relevant Nobel here) transformed atomic physics from what had been a comparatively sleepy specialty, concerned with measuring details of optical transitions and precision spectroscopy (useful for atomic clocks), into a hive of activity, looking at the onset of new states of matter that happen when gases become sufficiently cold and dense that their quantum statistics start to be important.  In a classical noninteracting gas, there are few limits on the constituent molecules - as long as they don't actually try to be in the same place at the same time (think of this as the billiard ball restriction), the molecules can take on whatever spatial locations and momenta that they can reach.  However, if a gas is very cold (low average kinetic energy per molecule) and dense, the quantum properties of the constituents matter - for historical reasons this is called the onset of "degeneracy".  If the constituents are fermions, then the Pauli principle, the same physics that keeps all 79 electrons in an atom of gold from hanging out in the 1s orbital, keeps the constituents apart, and keeps them from all falling into the lowest available energy state.   In contrast, if the constituents are bosons, then a macroscopic fraction of the constituents can fall into the lowest energy state, a process called Bose-Einstein condensation (relevant Nobel here); the condensed state is a single quantum state with a large occupation, and therefore can show exotic properties.

Prof. Jin's group did landmark work with these systems.  She and her student Brian DeMarco showed that you could actually reach the degenerate limit in a trapped atomic Fermi gas.  A major challenge in this field is trying to avoid 3-body and other collisions that can create states of the atoms that are no longer trapped by the lasers and magnetic fields used to do the confinement, and yet still create systems that are (in their quantum way) dense.  Prof. Jin's group showed that you could actually finesse this issue and pair up fermionic atoms to create trapped, ultracold diatomic molecules.  Moreover, you could then create a Bose-Einstein condensate of molecules (since a pair of fermions can be considered as a composite boson).  In superconductors, we're used to the idea that electrons can form Cooper pairs, which act as composite bosons and form a coherent quantum system, the superconducting state.  However, in superconductors, the Cooper pairs are "large" - the average real-space separation between the electrons that constitute a pair is big compared to the typical separation between particles.  Prof. Jin's work showed that in atomic gases you could span between the limits (BEC of tightly bound molecules on the one hand, vs. condensed state of loosely paired fermions on the other).  More recently, her group had been doing cool work looking at systems good for testing models of magnetism and other more complicated condensed matter phenoma, by using dipolar molecules, and examining very strongly interacting fermions.   Basically, Prof. Jin was an impressively creative, technically skilled, extremely productive physicist, and by all accounts a generous person who was great at mentoring students and postdocs.   She has left a remarkable scientific legacy for someone whose professional career was tragically cut short, and she will be missed.

Sunday, September 18, 2016

Alan Alda Center for Communicating Science, posting

Tomorrow I'll be a participant in an all-day workshop that Rice's Center for Teaching Excellence will be hosting with representatives from the Alan Alda Center for Communicating Science - the folks responsible for the Flame Challenge, a contest about trying to explain a science topic to an 11-year-old.  I'll write a follow-up post sometime soon about what this was like.

I'm in the midst of some major writing commitments right now, so posting frequency may slow for a bit.  I am trying to plan out how to write some accessible content about some recent exciting work in a few different material systems. 


Monday, September 12, 2016

Professional service

An underappreciated part of a scientific career is "professional service" - reviewing papers and grant proposals, filling roles in professional societies, organizing workshops/conferences/summer schools - basically carrying your fair share of the load, so that the whole scientific enterprise actually functions.  Some people take on service roles primarily because they want to learn better how the system works; others do so out of altruism, realizing that it's only fair, for example, to perform reviews of papers and grants at roughly the rate you submit them; still others take on responsibility because they either think they know best how to run/fix things, or because they don't like the alternatives.   Often it's a combination of all of these.

More and more journals proliferate; numbers of grant applications climb even as (in the US anyway) support remains flat or declining; and conference attendance continues to grow (the APS March Meeting is now twice as large as in my last year of grad school).  This means that professional demands are on the rise.  At the same time, it is difficult to track and quantify (except by self-reporting) these activities, and reward structures give only indirect incentive (e.g., reviewing grants gives you a sense of what makes a better proposal) to good citizenship.  So, when you're muttering under your breath about referee number 3 or about how the sessions are organized nonoptimally at your favorite conference (as we all do from time to time), remember that at least the people in question are trying to contribute, rather than sitting on the sidelines.

Friday, September 02, 2016

Conference for Undergraduate Women in Physics!

Over January 13-15, 2017, Rice is going to be hosting one of the American Physical Society's Conferences for Undergraduate Women in Physics.  Registration is now open - please click on the link in the previous sentence, and you will be taken to the meeting website.  This is one of about 10 regional CUWiP meetings, and our region encompasses Texas, Mississippi, Alabama, Florida, Arkansas, and Louisiana.  Many thanks to my faculty colleagues Prof. Marj Corcoran and Prof. Pat Reiff for leading the way on this, and to our staff administrator and our excellent SPAS undergraduates for their efforts.