APS March Meeting, Day 1

As in past years, I'm going to try to give a few highlights of talks that I saw "at" the APS March Meeting.  Historically these are a blend of talks that usually have some connection to research topics that interest me, and subjects that I think are likely to be important or presented by particularly good speakers.  The meeting being virtual this year presents challenges.  On the one hand, because a very large fraction of the talks are being recorded, in principle I should be able to go back and watch anything that I otherwise would miss due to scheduling collisions or other commitments.  On the other hand, not traveling means that it's very hard to truly concentrate on the meeting without local work demanding some attention.  

(To simulate the true March Meeting experience, I was tempted to spend $4.50 on some terrible coffee this morning, and $11 on a slice of turkey, a slice of cheese, a sad slice of tomato, and a wilted lettuce leaf on white bread for lunch.)

• Tim Hugo Taminiau from Delft presented a neat talk about using (the electron spins of) NV centers in diamond to examine and control ¹³C nuclear spins.  Through very impressive pulse sequences based on NMR techniques plus machine learning, his group has been able to determine the locations and couplings of tens of nuclear spins, and controllably create and manipulate entanglement among them.
• Markus Raschke from Colorado gave a very nice presentation showcasing the impressive work that his group has done using the plasmonic resonance of a gold tip to do cavity quantum electrodynamics with individual emitters.   Even though the plasmonic cavity is leaky (low \(Q\)), the mode volume is tiny compared with the wavelength (\(V_{m} \sim 10^{-6} \lambda^{3}\)).  This lets them get into the strong coupling regime, with big splittings of the excitonic emission peaks in quantum dots and clear detection of the plexitonic (or polaritonic, depending on your terminology) states.
• 
  There was a nice session about strange metals, but I had to pop in and out of it.  One particularly interesting talk was given by Philip Phillips, who spoke about Noether's theorem(s) and the demise of charge quantization in the strange metal - see here.  (This relates to an experiment I'm very interested in trying.)  This talk also featured an unscheduled interruption for the first APS/Marvel's WandaVision crossover (see image).
  
• Late in the day I was able to catch most of Bart van Wees's talk about spin transport in magnetic insulators, including the spin Seebeck effect.  The basic measurement approach is this one, using the inverse spin Hall effect to detect an incoming current of magnons driven either by spin injection or by a temperature gradient.  They have applied this approach to examine a number of material systems, including van der Waals antiferromagnets and the van der Waals Ising magnet CrBr₃.  In the latter case, because the material is so chemically reactive, they had to do some clever sample fabrication to encapsulate it in hBN while countersinking their Pt spin Hall electrodes.
• I also managed to see Bob Willett's talk about showing actual interferometric demonstration of non-Abelian statistics at the \(\nu = 5/2\) and \(7/2\) fractional quantum Hall states.  These devices are amazing in that they preserve the material quality despite challenging fabrication, and the experiments are about the clearest evidence you can have for exotic fractional charge and statistics in these systems.

There are some other talks from today that I want to see, but they will have to wait.  The virtual meeting format is ok, but there really is no substitute for talking to people face to face.