Many things have been happening in and around US science.  This is a non-exhaustive list of recent developments and links: There have been very large scale personnel cuts across HHS, FDA, CDC, NIH - see here.  This includes groups like the people who monitor lead in drinking water.   There is reporting about the upcoming presidential budget requests about NASA and NOAA.  The requested cuts are very deep.  To quote Eric Berger's article linked above, for the science part of NASA, "Among the proposals were: A two-thirds cut to astrophysics, down to $487 million; a greater than two-thirds cut to heliophysics, down to $455 million; a greater than 50 percent cut to Earth science, down to $1.033 billion; and a 30 percent cut to Planetary science, down to $1.929 billion."  The proposed cuts to NOAA are similarly deep, seeking to end climate study in the agency, as Science puts it. The full presidential budget request, including NSF, DOE, NIST, etc. is still to come.  Remember, Congress in the past has often essentially ignored presidential budget requests.  It is unclear if the will exists to do so now.  Speaking of NSF, the graduate research fellowship program award announcements for this year came out this past week.  The agency awarded slightly under half as many of these prestigious 3-year fellowships as in each of the last 15 years.  I can only presume that this is because the agency is deeply concerned about its budgets for the next couple of fiscal years. Grants are being frozen at several top private universities - these include Columbia (new cancellations), the University of Pennsylvania (here), Harvard (here), Northwestern and Cornell (here), and Princeton (here).  There are various law suits filed about all of these.  Princeton and Harvard have been borrowing money (issuing bonds) to partly deal with the disruption as litigation continues.  The president of Princeton has been more vocal than many about this. There has been a surge in visa revocations and unannounced student status changes in SEVIS for international students in the US.  To say that this is unsettling is an enormous understatement.  See here for a limited discussion.  There seems to be deep reluctance for universities to speak out about this, presumably from the worry that saying the wrong thing will end up placing their international students and scholars at greater exposure. On Friday evening, the US Department of Energy put out a "policy flash", stating that indirect cost rates on its grants would be cut immediately to 15%.  This sounds familiar.  Legal challenges are undoubtedly beginning.   Added bonus:  According to the Washington Post, DOGE (whatever they say they are this week) is now in control of grants.gov, the website that posts funding opportunities.  As the article says, "Now the responsibility of posting these grant opportunities is poised to rest with DOGE — and if its employees delay those postings or stop them altogether, 'it could effectively shut down federal-grant making,' said one federal official who spoke on the condition of anonymity to describe internal operations."   None of this is good news for the future of science and engineering research in the US.  If you are a US voter and you think that university-based research is important, I encourage you to contact your legislators and make your opinions heard.   (As I have put in my profile, what I write here are my personal opinions; I am not in any way speaking for my employer.  That should be obvious, but it never hurts to state it explicitly.)

Here are a couple of neat papers that I came across in the last week.  (Planning to write something about multiferroics as well, once I have a bit of time.) The idea of directly extracting useful energy from the rotation of the earth sounds like something out of an H. G. Wells novel.  At a rough estimate (and it's impressive to me that AI tools are now able to provide a convincing step-by-step calculation of this; I tried w/ gemini.google.com) the rotational kinetic energy of the earth is about \(2.6 \times 10^{29}\) J.  The tricky bit is, how do you get at it?  You might imagine constructing some kind of big space-based pick-up coil and getting some inductive voltage generation as the earth rotates its magnetic field past the coil.  Intuitively, though, it seems like while sitting on the (rotating) earth, you should in some sense be comoving with respect to the local magnetic field, so it shouldn't be possible to do anything clever that way.  It turns out, though, that Lorentz forces still apply when moving a wire through the axially symmetric parts of the earth's field.  This has some conceptual contact with Faraday's dc electric generator.   With the right choice of geometry and materials, it is possible to use such an approach to extract some (tiny at the moment) power.  For the theory proposal, see here.  For an experimental demonstration, using thermoelectric effects as a way to measure this (and confirm that the orientation of the cylindrical shell has the expected effect), see here.  I need to read this more closely to decide if I really understand the nuances of how it works. On a completely different note, this paper came out on Friday.  (Full disclosure:  The PI is my former postdoc and the second author was one of my students.)  It's an impressive technical achievement.  We are used to the fact that usually macroscopic objects don't show signatures of quantum interference.  Inelastic interactions of the object with its environment effectively suppress quantum interference effects on some time scale (and therefore some distance scale).  Small molecules are expected to still show electronic quantum effects at room temperature, since they are tiny and their electronic levels are widely spaced, and here is a review of what this could do in electronic measurements.  Quantum interference effects should also be possible in molecular vibrations at room temperature, and they could manifest themselves through the vibrational thermal conduction through single molecules, as considered theoretically here.  This experimental paper does a bridge measurement to compare the thermal transport between a single-molecule-containing junction between a tip and a surface, and an empty (farther spaced) twin tip-surface geometry.  They argue that they see differences between two kinds of molecules that originate from such quantum interference effects. As for more global issues about the US research climate, there will be more announcements soon about reductions in force and the forthcoming presidential budget request.  (Here is an online petition regarding the plan to shutter the NIST atomic spectroscopy group.)  Please pay attention to these issues, and if you're a US citizen, I urge you to contact your legislators and make your voice heard.

I saw a couple of interesting talks this morning before heading out: Alessandro Chiesa of Parma spoke about using spin-containing molecules potentially as qubits, and about chiral-induced spin selectivity (CISS) in electron transfer.  Regarding the former, here is a review.  Spin-containing molecules can have interesting properties as single qubits, or, for spins higher than 1/2, qudits, with unpaired electrons often confined to a transition metal or rare earth ion somewhat protected from the rest of the universe by the rest of the molecule.  The result can be very long coherence times for their spins.  Doing multi-qubit operations is very challenging with such building blocks, however.  There are some theory proposals and attempts to couple molecular qubits to superconducting resonators, but it's tough!   Regarding chiral induced spin selectivity, he discused recent work trying to use molecules where a donor region is linked to an acceptor region via a chiral bridge, and trying to manipulate spin centers this way.  A question in all the CISS work is, how can the effects be large when spin-orbit coupling is generally very weak in light, organic molecules?  He has a recent treatment of this, arguing that if one models the bridge as a chain of sites with large \(U/t\), where \(U\) is the on-site repulsion energy and \(t\) is the hopping contribution, then exchange processes between sites can effectively amplify the otherwise weak spin-orbit effects.  I need to read and think more about this. Richard Schlitz of Konstanz gave a nice talk about some pretty recent research using a scanning tunneling microscope tip (with magnetic iron atoms on the end) to drive electron paramagnetic resonance in a single pentacene molecule (sitting on MgO on Ag, where it tends to grab an electron from the silver and host a spin).  The experimental approach was initially explained here.  The actual polarized tunneling current can drive the resonance, and exactly how depends on the bias conditions.  At high bias, when there is strong resonant tunneling, the current exerts a damping-like torque, while at low bias, when tunneling is far off resonance, the current exerts a field-like torque.  Neat stuff. Leah Weiss from Chicago gave a clear presentation about not-yet-published results (based on earlier work), doing optically detected EPR of Er-containing molecules.  These condense into mm-sized molecular crystals, with the molecular environment being nice and clean, leading to very little inhomogeneous broadening of the lines.  There are spin-selective transitions that can be driven using near telecom-wavelength (1.55 \(\mu m\)) light.  When the (anisotropic) \(g\)-factors of the different levels are different, there are some very promising ways to do orientation-selective and spin-selective spectroscopy.  Looking forward to seeing the paper on this. And that's it for me for the meeting.  A couple of thoughts: I'm not sold on the combined March/April meeting.  Six years ago when I was a DCMP member-at-large, the discussion was all about how the March Meeting was too big, making it hard to find and get good deals on host sites, and maybe the meeting should split.  Now they've made it even bigger.  Doesn't this make planning more difficult and hosting more expensive since there are fewer options?  (I'm not an economist, but....)  A benefit for the April meeting attendees is that grad students and postdocs get access to the career/networking events held at the MM.  If you're going to do the combination, then it seems like you should have the courage of your convictions and really mingle the two, rather than keeping the March talks in the convention center and the April talks in site hotels. I understand that van der Waals/twisted materials are great laboratories for physics, and that topological states in these are exciting.  Still, by my count there were 7 invited sessions broadly about this topic, and 35 invited talks on this over four days seems a bit extreme.   By my count, there were eight dilution refrigerator vendors at the exhibition (Maybell, Bluefors, Ice, Oxford, Danaher/Leiden, Formfactor, Zero-Point Cryo, and Quantum Design if you count their PPMS insert).  Wow.   I'm sure there will be other cool results presented today and tomorrow that I am missing - feel free to mention them in the comments.

Another busy day at the APS Global Physics Summit.  Here are a few highlights: Shahal Ilani of the Weizmann gave an absolutely fantastic talk about his group's latest results from their quantum twisting microscope.  In a scanning tunneling microscope, because tunneling happens at an atomic-scale location between the tip and the sample, the momentum in the transverse direction is not conserved - that is, the tunneling averages over a huge range of \(\mathbf{k}\) vectors for the tunneling electron.  In the quantum twisting microscope, electrons tunnel from a flat (graphite) patch something like \(d \sim\) 100 nm across, coherently, through a couple of layers of some insulator (like WSe2) and into a van der Waals sample.  In this case, \(\mathbf{k}\) in the plane is comparatively conserved, and by rotating the sample relative to the tip, it is possible to build up a picture of the sample's electronic energy vs. \(\mathbf{k}\) dispersion, rather like in angle-resolved photoemission.  This has allowed, e.g., mapping of phonons via inelastic tunneling.  His group has applied this to magic angle twisted bilayer graphene, a system that has a peculiar combination of properties, where in some ways the electrons act like very local objects, and in other ways they act like delocalized objects.  The answer seems to be that this system at the magic angle is a bit of an analog of a heavy fermion system, where there are sort of local moments (living in very flat bands) interacting and hybridizing with "conduction" electrons (bands crossing the Fermi level at the Brillouin zone center).  The experimental data (movies of the bands as a function of energy and \(\mathbf{k}\) in the plane as the filling is tuned via gate) are gorgeous and look very much like theoretical models. I saw a talk by Roger Melko about applying large language models to try to get efficient knowledge of many-body quantum states, or at least the possible outputs of evolution of a quantum system like a quantum computer based on Rydberg atoms.  It started fairly pedagogically, but I confess that I got lost in the AI/ML jargon about halfway through. Francis M. Ross, recipient of this year's Keithley Award, gave a great talk about using transmission electron microscopy to watch the growth of materials in real time.  She had some fantastic videos - here is a review article about some of the techniques used.  She also showed some very new work using a focused electron beam to make arrays of point defects in 2D materials that looks very promising. Steve Kivelson, recipient of this year's Buckley Prize, presented a very nice talk about his personal views on the theory of high temperature superconductivity in the cuprates.  One basic point:  these materials are balancing between multiple different kinds of emergent order (spin density waves, charge density waves, electronic nematics, perhaps pair density waves).   This magnifies the effects of quenched disorder, which can locally tip the balance one way or another.  Recent investigations of the famous 2D square lattice Hubbard model show this as well.  He argues that the ground state of the Hubbard model for a broad range \(1/2 < U/t < 8\), where \(U\) is the on-site repulsion and \(t\) is the hopping term, the ground state is in fact a charge density wave, not a superconductor.  However, if there is some amount of disorder in the form of \(\delta t/t \sim 0.1-0.2\), the result is a robust, unavoidable superconducting state.  He further argues that increasing the superconducting transition temperature requires striking a balance between the underdoped case (strong pairing, weak superfluid phase stiffness) and the overdoped case (weak pairing, strong superfluid stiffness), and that one way to achieve this would be in a bilayer with broken mirror symmetry (say different charge reservoir layers above and below, and/or a big displacement field perpendicular to the plane).  (Apologies for how technical that sounded - hard to reduce that one to something super accessible without writing much more.) A bit more tomorrow before I depart back to Houston.