A cool collaboration with István Kovács's group at Northwestern, that brings ideas from conformal field theory and quantum spin chains all the way to active matter!
Poke @nyuphysics.bsky.social

A great work with @stemartiniani.bsky.social at CSMR @nyuphysics.bsky.social, NYU Chemistry and @nyucourant.bsky.social !
Also, poke/thank you @remicarminati.bsky.social for helpful discussions and for helping me get back to optics 😄

Thanks! I will likely try it within a couple of days 😄

Hi 👀👀 I do the physics thing too!
orcid.org/0000-0002-53...

We need to see science as a social compact where it serves the larger world, not our own interests.

As a first step, scientists must communicate to the larger world much better.

I wrote an essay about this in 2016, which still holds today.

globalecoguy.org/science-comm...

More interestingly, the idea of gyromorphs and the recipe used to make them are easily extended to 3d materials, with a spherical shell of high values in S(k) instead of a ring, and to structures with several rings, or polygyromorphs.
We hope to test these exciting structures experimentally!

So, what about optics? We show that gyromorphs consistently outperform other aperiodic isotropic bandgap materials candidates at moderate refractive indices, within a coupled dipoles approximation. In fact, their bandgaps are about as deep as those of low-symmetry quasicrystals, but isotropic.

The obtained structures are distinct from quasicrystals, in that they have very broad g(r) features and only a handful of peaks in S(k). In particular, we show that gyromorphs achieve higher S(k) peaks than their de Bruijn quasicrystal counterparts, but lose large-k features.

These structures are obtained by an optimization procedure directly adapted from FReSCo, github.com/martiniani-l...
Basically, we only maximize the height of a ring of peaks at a chosen k-vector and forbid exact overlaps, but let the rest evolve freely in free boundary conditions.

Fun! NYU has been doing Physics on the Toilet inside the department for years too (brain teasers, not outreach), it does seem to create engagement among students 😄

And that took a bit longer than expected but: that's it for today. I'm glad to finally be able to talk about this project at large, it has been a very interesting and challenging work with @praharsh.bsky.social, now we have a lot of uncharted territory to explore with our brand new high-d sailboat!

This problem gets worse as the dimensionality of the problem, i.e. the number of spheres, grows. Eventually, only a vanishing fraction of initial configurations map to the right minimum using optimization strategies, highlighting the importance of careful ODE solving to study landscapes.

Our main result is that optimizers scramble the energy landscape and bias the observed basin shapes and minimum energies. Worse, it makes the basins appear very jagged and rough, giving an impression of fractality. We dispel this mirage and show that accurate ODE solving yields smooth features.

In that case, identifying basins is a challenging numerical task - steepest descent becomes a stiff ODE problem and naïve explicit forward-Euler schemes commonly used by physicists become very unstable, thus very costly. Thus, people have turned to cheaper optimization strategies like 🔥FIRE🔥.

These basins determine low-temperature physics. If a system has a global minimum of energy surrounded by a massive basin, it will most often nicely cool down to find one configuration. In complex systems though it is common to have very (!) MANY (!) low-lying narrow basins: this is glassiness.

These basins of attraction, which you can think of as drainage basins for rivers: just like a droplet of water dropped into the Midwest will eventually join the Mississippi then the Gulf of Mexico, any initial configuration in a solid colored region will flow to the same final configuration.

Pretty video right? You just experienced travel through the 30-dimensional configurational space of 16 soft repulsive disks in a 2d periodic square box. The colored regions encoded "basins" in which all configurations would fall to the same minimum if the spheres were rapidly cooled down.

Oh and, while I obviously worked on the numerical and analytical aspects of the work, this paper includes experiments from collaborators in the Netherlands!
Yay, real-world physics!