APS March Meeting 2022, Day 2

It was a busy day today, and I saw a lot of talks, some live and in person, some live via zoom, and some prerecorded.  Some highlights:

• Started off with Nai Phuan Ong's invited talk about their recent results on thermal transport measurements in the proximate Kitaev spin liquid material \(\alpha\)-RuCl3.  His group performs measurements of the longitudinal thermal conductivity \(\kappa_{xx}\) and the thermal Hall conductivity \(\kappa_{xy}\) in this system by gluing tiny thermometers to the very delicate crystals.  They see some remarkable results, including evidence that there are heat-carrying bosonic (not fermionic) edge modes.
• In a different session, I heard Dan Ralph talk about a variety of issues involved in really properly understanding all the pitfalls that can come into interpreting the different experimental attempts to measure SO torque efficiency.  
• This was followed by a nice talk by Alex McLeod about nanophotonic near-field probes of correlated materials.  The talk included a great history of the field, including this paper that I'd somehow never seen before. 
• Anand Bhattacharya gave a nice presentation about his group's work on 2D superconductivity at the interface of KTaO3 with other oxides, especially the dependence on crystallographic orientation.  They have another recent paper that explains features of the gate dependence of the superconducting transition, and there is a theoretical proposal for the underlying mechanism.
• Garnet Chan spoke on a very interesting topic:  Is there an exponential quantum advantage (relative to classical computing) to be had in using quantum computers to try to solve theoretical chemistry problems such as finding the ground state of a large molecule or material?  Such an advantage requires, among other things, that classical methods exponentially poorly with the problem size, and that initial state preparation of the quantum system is not exponentially difficult.  The short answer:  it's not clear that this is the case.  (Quantum computers could still be very useful for quantum chemistry.  Here is a relevant review article.)
• Mathieu Taupin from TU Wien spoke about superconductivity at very low temperatures in the quantum critical strange metal YbRh2Si2, and also about whether these kinds of heavy fermion strange metals are "Planckian".
• I also heard Linda Ye present data showing that Ni3In, a "kagome flat band" material, is a strange metal.  In this kind of system, because of the lattice structure and its symmetry, there is particular destructive quantum interference that happens to disfavor electronic hopping between certain lattice sites - see here.  As a result, the electrons in that band tend to localize, leading to an energy band that is flat.  In this system, that band sits at the Fermi level, and strange metallicity seems to result.

Besides the talks, I also got to see and catch up with a number of friends and colleagues for the first time since the pandemic started.  The exhibition show part of the meeting has changed quite a bit. It's really amazing how big a difference three years makes in terms of the exhibitors. Now it seems like 75% of the vendors there are "quantum"-related.