## Friday, June 14, 2013

### Come on, PRL editors.

I rarely criticize papers.  I write this not to single out the authors (none of whom I know), nor to criticize the actual science (which seems very interesting) but to ask pointedly:  How did the editors of PRL, a journal that allegedly prizes readability by a general physics audience, allow this to go through in its current form?  This paper is titled "Poor Man’s Understanding of Kinks Originating from Strong Electronic Correlations".  A natural question would be, "Kinks in what?".  Unfortunately, the abstract doesn't say.  Worse, it refers to "the central peak".  Again, a peak in what?!   Something as a function of something, that's for sure.

Come on, editors - if you are going to let articles be knocked from PRL contention because they're "more suitable for a specialized journal", that obligates you to make sure that the papers you do print at least have titles and abstracts that are accessible.  I'm even a specialist in the field and I wasn't sure what the authors were talking about (some spectral density function?) based on the title and abstract.

The authors actually do a good job explaining the issue in the very first sentence of the paper:  "Kinks in the energy vs. momentum dispersion relation indicate deviations from a quasiparticle renormalization of the noninteracting system."   That should have been the first sentence in the abstract.  In a noninteracting system, the relationship between energy and momentum of particles is smooth.  For example, for a free electron, $E = p^{2}/2m$ where $m$ is the mass.  In an ordinary metal (where Fermi liquid theory works), you can write a similar smooth relationship for the energy vs. momentum relationship of the quasiparticles. Kinks in that relationship, as the authors say, "provide valuable information of many-body effects".

## Wednesday, June 12, 2013

Ordinarily I wouldn't just post a link, but this article ("Self-Sabotage in the Academic Career: 15 ways in which faculty members harm their own futures, often without knowing it") from the Chronicle of Higher Education is exceptionally good advice for new faculty members.  While several of the points are specific to academia, some are generalizable to any career within a moderately large organization.

## Friday, June 07, 2013

### The state of "molecular electronics"

For those interested in the history and current state of "molecular electronics", I refer you to the latest focus issue of Nature Nanotechnology.  Good news for those without subscription access - some good articles are available free of charge:

## Wednesday, June 05, 2013

### Rescheduled, Workshop on Surface Plasmons, Metamaterials, and Catalysis

Three of my colleagues and I are helping to organize a workshop at Rice University on October 21-23, 2013.   (This had originally been planned for May, but sequester-related travel restrictions on the government participants among other things forced a rescheduling.)  The goal of this ARO-sponsored workshop is to explore the opportunities for chemical catalysis arising from recent advances in the fields of metamaterials and plasmonics.  The workshop will bring together scientists from the disciplines of electrochemistry, catalysis, and plasmonics, which have not traditionally had a common platform.

The confirmed invited speakers are:

Rick Van Duyne - Northwestern University
Paul Bohn - University of Notre Dame
Martin Moskovits - University of California, Santa Barbara
Katherine Willets - University of Texas at Austin
Jennifer Dionne - Stanford University
Mark Brongersma - Stanford University
Louis Brus - Columbia University
Harry Atwater - California Institute of Technology
John Yates - University of Virginia
Mengyan Shen - University of Massachusetts, Lowell
Suljo Linic - University of Michigan
Mostafa El-Sayed –- Georgia Tech
Tom Mallouk –- Penn State

Topics include:

• The state of the art in plasmonics, metamaterials, and chemical catalysis
• Areas of catalysis that could benefit from enhanced optical/electromagnetic concepts
• Concepts for nanophotonic- and metamaterials-driven catalysis and heat generation
• Surface nanoengineering to merge nanophotonics and catalysis
• Quantum plasmonics
• Hot electrons driving chemistry
• Chemical sensing using nanophotonic and plasmonic concepts
• Nanophotonic characterization of catalytic structures:  Where do the reactions happen, and how fast?
The deadline for abstract submission is July 21, 2013, and space is limited.  The workshop website is here:  http://PlasEnhCat2013.rice.edu  .

Please feel free to distribute this information to people that would be interested!

## Wednesday, May 29, 2013

### What does "heating" mean at the nanoscale?

I've talked before about what physicists mean when they talk about "temperature", and work has me thinking about this a lot these days. Temperature is inherently a statistical concept.  It doesn't really make sense to talk about the temperature of a single electron.  The electron has some momentum (and therefore some kinetic energy), but temperature is not a meaningful concept for a single particle in isolation.  Now, if you have a whole bunch of electrons, you can talk about how many of them have a certain amount of energy.  That distribution of electrons as a function of energy takes on a particular form when the electron system is in thermal equilibrium.  (That is, if the electron system is weakly coupled somehow to an energy reservoir so that energy can be exchanged freely between the reservoir and the electrons.)  When the electron system is in thermal equilibrium with the reservoir, on average no net energy is transferred as a function of time between the electrons and the reservoir; this is what we mean when we say that the electrons and the reservoir have the same temperature.

The situation gets really tricky when a system is driven out of equilibrium.  For example, you can use a battery to drive electrons through some nanoscale system.  When you do that, and you look at different points within the nanoscale system, you will find that, in general, the distribution of the electrons as a function of energy doesn't necessarily look much like the thermal equilibrium case.  So, is there a sensible way to generalize the idea of temperature to quantify how "hot" the electrons are?  The problem is, there are many ways you might want to do this - you are trying to take a potentially very complicated distribution function and essentially summarize it by a single number, some local effective temperature.   A natural direction to go is to consider a thought experiment:  what if you took a reservoir with a well defined equilibrium temperature, and allowed it to exchange energy with the nonequilibrium system at a location of interest.  What reservoir temperature would you have to pick so that there is no net average energy transfer between the system and the reservoir in steady state?   That is one sensible way to go, but in the nano limit the situation can be very tricky, even in the thought experiment.  The details of how the imagined energy exchange takes place can affect the answers you get.  Tough stuff.

## Thursday, May 23, 2013

### Instructor opening at Rice

RICE UNIVERSITY
Wiess Instructorship in Physics and Astronomy

The Physics and Astronomy Department at Rice University invites applications for a one-year instructorship position teaching introductory physics, commencing July/August 2013.  The teaching load is equivalent to two courses per semester.  There would also be opportunities to develop innovative teaching methods and pursue independent research or collaborations with existing research programs (see web page http://physics.rice.edu).  Evaluation of applications will begin immediately and continue until the position is filled. Applicants should send a curriculum vitae, a statement of teaching and research interests, and a list of publications as a single PDF file, and should arrange for three letters of reference to be sent to: vcall@rice.edu with subject line "Wiess Instructorship" (pdf format preferred), or by postal mail to Wiess Instructorship Search, c/o Valerie Call, Physics and Astronomy Department-MS61, Rice University, 6100 Main Street, Houston, TX 77005-1892. Applicants must have a PhD and be eligible to work in the U.S. Rice University is an affirmative action/equal opportunity employer.