Anisotropic decomposition: a compass and a map to design patchy particles interactions
Pietro Caracciolo Di Torella (LPTMS, Orsay)
Self-assembly is the process by which individual building blocks spontaneously organize into larger aggregates. A widely used approach to model this process relies on patchy particles, where anisotropic interactions are encoded through patches on the particle surface and the structures that emerge are determined by which pairs of patches attract or repel one another. A natural parametrization of particle interactions assigns an independent interaction energy to each distinct patch–patch contact. However, translating many local patch–patch rules into global structural outcomes is far from intuitive, and becomes increasingly challenging as the number of patch types grows. Here we introduce a class of two- and three-dimensional lattice models of patchy particles for which, using tools from group theory, the full interaction matrix can be analytically decomposed into a set of anisotropic modes, each possessing well-defined symmetry properties. We then show that each anisotropic mode has a distinct and interpretable effect on the macroscopic properties of the assembled structure. By rewriting the interactions in this way, we can both understand why a given set of interactions produces a particular aggregate and design interactions that target desired structural outcomes.
Breaking of clustering and macroscopic quantum coherence out of equilibrium
Florent Ferro (LPTMS, Orsay)
We investigate the dynamics of symmetry-breaking states under both non-interacting [1] and interacting [2] Hamiltonians following a local quench. We show that such states exhibit a breakdown of clustering properties at ballistic scales, resulting in anomalously large fluctuations of extensive order parameters. Using the Quantum Fisher Information (QFI), we show that this setting is an ideal framework for the emergence of macroscopic quantum coherence. Specifically, we show that the breaking of clustering allows the system to develop coherence at scales proportional to the time after the quench. Our findings presents this scenario as one of the most natural ways to develop cat-like states from product states through simple local interactions.
[1]: F Ferro and M Fagotti, arxiv.org/abs/2503.21905
[2]: F Ferro, arxiv.org/abs/2602.15969