New paper just out, as an editor's suggestion in PRL!

While looking for the ideal isotropic bandgap material, we actually discovered new structures.
These structures lie at the border between order and disorder, and that's good for optics!

More about their structure here,
tinyurl.com/3aej53ht

⚛️🧪

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.

Ok, last update: how to make isotropic bandgaps? At low index contrast, the answer is aperiodic structures, e.g. quasicrystals. We propose that the best material would have a structure factor as close as possible to being just one ring of high values: enter gyromorphs. arxiv.org/abs/2410.09023

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.

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.

Next up: for a change of scenery, let's look at energy landscapes! We showed that numerical commonly used to study the location, energy, and entropic bias of minima in jammed soft spheres completely destroy the geometry of the landscape, and provide an alternative.
arxiv.org/abs/2409.121...

A last look at the Alps after a fantastic two weeks at Les Houches -- with a nice Kelvin-Helmholtz instability waving goodbye 🌊
Kudos to the organizers, it's been a fantastic two weeks!

After a few years away from both Europe and optics, what better way to reconnect than going to Les Houches? 😄🏔️
And yes, spoiler alert, photonics is coming back to my research very soon 👀