Friday, September 30, 2022

Rice University physics faculty searches in quantum

The Department of Physics and Astronomy at Rice University invites applications for a tenure-track faculty position in the area of experimental quantum science using atomic, molecular, or optical methods.  This encompasses quantum information processing, quantum sensing, quantum communication, quantum opto-mechanics, quantum many-body physics, and quantum simulation conducted on a variety of platforms. We seek outstanding scientists whose research will complement and extend existing quantum activities within the Department and across the University (Rice Quantum Initiative: https://quantum.rice.edu/). In addition to developing an independent and vigorous research program, the successful candidates will be expected to teach, on average, one undergraduate or graduate course each semester, and contribute to the service missions of the Department and University. The Department anticipates making an appointment at the assistant professor level. A Ph.D. in physics or related field is required by December 31, 2022.

Applications for this position must be submitted electronically at apply.interfolio.com/114465. Applicants will be required to submit the following: (1) cover letter; (2) curriculum vitae; (3) statement of research; (4) statement on teaching; (5) statement on diversity, mentoring, and outreach; (6) PDF copies of up to three publications; and (7) the names, affiliations, and email addresses of three professional references. Rice University, and the Department of Physics and Astronomy, are strongly committed to a culturally diverse intellectual community. In this spirit, we particularly welcome applications from all genders and members of historically underrepresented groups who exemplify diverse cultural experiences and who are especially qualified to mentor and advise all members of our diverse student population. We will begin reviewing applications by November 15, 2022. To receive full consideration, all application materials must be received by January 1, 2023. The expected appointment date is July, 2023.

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The Department of Physics and Astronomy at Rice University invites applications for a tenure-track faculty position in the area of theoretical quantum science using atomic, molecular, or optical methods.  This encompasses quantum information processing, quantum sensing, quantum communication, quantum opto-mechanics, quantum many-body physics, and quantum simulation conducted on a variety of platforms. The ideal theorist will intellectually connect AMO physics to topics in condensed matter and quantum information theory. We seek outstanding scientists whose research will complement and extend existing quantum activities within the Department and across the University (Rice Quantum Initiative: https://quantum.rice.edu/). In addition to developing an independent and vigorous research program, the successful candidates will be expected to teach, on average, one undergraduate or graduate course each semester, and contribute to the service missions of the Department and University. The Department anticipates making an appointment at the assistant professor level. A Ph.D. in physics or related field is required by December 31, 2022.

Applications for this position must be submitted electronically at apply.interfolio.com/114467. Applicants will be required to submit the following: (1) cover letter; (2) curriculum vitae; (3) statement of research; (4) statement on teaching; (5) statement on diversity, mentoring, and outreach; (6) PDF copies of up to three publications; and (7) the names, affiliations, and email addresses of three professional references. Rice University, and the Department of Physics and Astronomy, are strongly committed to a culturally diverse intellectual community. In this spirit, we particularly welcome applications from all genders and members of historically underrepresented groups who exemplify diverse cultural experiences and who are especially qualified to mentor and advise all members of our diverse student population. We will begin reviewing applications by November 15, 2022. To receive full consideration, all application materials must be received by January 1, 2023. The expected appointment date is July, 2023.

Rice University is an Equal Opportunity Employer with commitment to diversity at all levels, and considers for employment qualified applicants without regard to race, color, religion, age, sex, sexual orientation, gender identity, national or ethnic origin, genetic information, disability or protected veteran status.

Wednesday, September 28, 2022

News items, Nobel speculation

 Some news items of interest:

  • Three weeks old now, but this story about IBM cooling down their enormous dilution refrigerator setup got my attention (as someone with ultralow temperature scientific roots).  IBM did this to demonstrate that this kind of large-scale cooling is possible, since it may be necessary for some implementations (whether superconducting or spin-based) of quantum computing.  To give a sense of scale, Oxford Instruments used to rate their dilution refrigerators based on their cooling power at 100 mK (how much heat could you dump into the system and still have it maintain a steady 100 mK temperature).  The system I worked on in grad school was pretty large, a model 400, meaning it had 400 microwatts of cooling power at 100 mK.  The new IBM setup can handle six dilution refrigerator units with a total cooling power of 10 mW (25 times more cooling capacity) at 100 mK, and with plenty of room for lots of electronic hardware.  Dil fridges are somewhat miraculous, in that they give access to temperatures far below what is readily available in nature thanks to the peculiarities of the 3He/4He mixture phase diagram. 
  • This retraction and the related news article are quite noteworthy.  The claim of room temperature superconductivity in carbon-containing hydrogen-rich material at very high pressures (written about here) has been retracted by the editors of Nature over the objection of the authors.    The big issue, as pointed out by Hirsch and van der Marel, is about the magnetic susceptibility data, the subtraction of a temperature-dependent background, and concerns whether this was done incorrectly (or misleadingly/fraudulently).  
  • Can we all agree, after looking at images like the one in this release, that STM and CO-functionalized-tip AFM are truly amazing techniques that show molecules really do look like chemistry structural diagrams from high school?
  • Quanta magazine has a characteristically excellent article about patterns arising when curved elastic surfaces are squished flat.  
  • They also have an article about this nice experiment (which I have not read in detail).  I need to look at this further, but it's a safe bet to say that many will disagree with the claim (implied by the article headline) that this has now solved the high temperature superconductivity problem to completion.  
And it's that time of year again to speculate about the Nobel prizes.  It would seem that condensed matter is probably due, given the cyclic history of the physics prize.  There are many candidates that have been put forward in previous years (topological insulators; metamaterials; qc lasers; twisted materials; multiferroics; anyons; my always-wrong favorite of geometric phases) as well as quantum optics (Bell's Inequalities).  I suspect the odds-on favorite for the medicine prize would be mRNA-based vaccines, but I don't know the field at all.  Feel free to gossip in the comments.

Friday, September 16, 2022

Surprising spin transport in insulating VO2

Monoclinic VO2,
adapted from here

As I wrote last year, techniques have been developed in the last decade or two that use the inverse spin Hall effect as a tool for measuring the transport of angular momentum in insulators.  We just applied this approach to look at the thermally driven transport of spin-carrying excitations (the spin Seebeck effect) in thin films of vanadium dioxide at low temperatures.  VO2 is a strongly correlated transition metal oxide that has a transition at 65C between a high temperature (rutile structure) metallic state with 1D vanadium chains, and a low temperature (monoclinic structure) insulating state in which the vanadium atoms have formed dimers, as shown at right.  I circled one V-V dimer in purple.  

The expectation, going back almost 50 years, is that in each dimer the unpaired d electrons on the vanadium atoms form a singlet, and thus the insulating state should be magnetically very boring.  That's why the result of our recently published paper are surprising.  In the "nonlocal" geometry (with a heater wire and a detector wire separated laterally on the surface of a VO2 film), we see a clear spin Seebeck signal that increases at temperatures below 30-40 K, indicating that some spin-carrying excitations are being thermally excited and diffusing from the heater to the detector.   One natural suspect would be thermally activated triplet excitations called triplons, and we are continuing to take data in other geometries and to try to nail down whether that is what is happening here.  

This has been a fun project, in part because I get a real kick out of the fact that this measurement technique is so simple and first-year undergrad physics says that you should see nothing.  We are running ac current back and forth in one wire at a few Hz, and measuring the voltage across a neighboring wire at twice that frequency, on an insulating substrate.  Instead of seeing nothing, because of the hidden action of spin in the insulator and spin-orbit physics in the wires, we see a clear signal that depends nontrivially on magnetic field magnitude and direction as well as temperature.  Gets me every time.  

Monday, September 05, 2022

Coming next month....


I'm going to be presenting a continuing education course starting next month, trying to give a general audience introduction to some key ideas about condensed matter and materials physics.   

From the intro flyer:  "The world and the materials that compose it are full of profound phenomena often overlooked by the uninitiated, from quasiparticles to the quantum world. Did you know that there are hundreds of states of matter? Have you ever wondered why objects can’t pass through each other and why stars don’t collapse? What do sports fans doing the wave or a traffic slowdown on the 610 Loop have to do with electrical conduction in metal? Why are raindrops wet and how do snowflakes achieve their delicate sixfold symmetry? Learn how physics affects everything around you, defining the very laws of nature. Spanning physics, chemistry, materials science, electrical engineering and even a bit of biology, this course brings the foundations of everyday physics to life and shares some of the most intriguing research emerging today."

Here is the link for registration for the course.  (The QR code I'd originally posted seems to point to the wrong class.)

(My posting has been less frequent as I continue to work on preparing this class.  Should be fun.)