Paired Parton Trial States for the Superfluid-Fractional Chern Insulator Transition
ArXiv preprint
Abstract:
We consider a model of hard-core bosons on a lattice, half-filling a Chern band such that the system has a continuous transition between a fractional Chern insulator (FCI) and a superfluid state (SF) depending on the bandwidth to bandspacing ratio. We construct a parton-inspired trial wavefunction ansatz for the ground states that has remarkably high overlap with exact diagonalization in both phases and throughout the phase transition. Our ansatz is stable to adding some bosonic interactions beyond the on-site hard core constraint. We confirm that the transition is well described by a projective translation symmetry-protected multiple parton band gap closure, as has been previously predicted. However, unlike prior work, we find that our wavefunctions require anomalous (BCS-like) parton correlations to describe the phase transition and SF phase accurately.
Enhanced Stability and Chaotic Condensates in Multispecies Nonreciprocal Mixtures.
Physical review letters 134:14 (2025) 148301
Abstract:
Random nonreciprocal interactions between a large number of conserved densities are shown to enhance the stability of the system toward pattern formation. The enhanced stability is an exact result when the number of species approaches infinity and is confirmed numerically by simulations of the multispecies nonreciprocal Cahn-Hilliard model. Furthermore, the diversity in dynamical patterns increases with an increasing number of components, and novel steady states such as pulsating or spatiotemporally chaotic condensates are observed. Our results may help to unravel the mechanisms by which living systems self-organize via metabolism.A closed band-projected density algebra must be Girvin-MacDonald-Platzman
Physical Review Letters American Physical Society 134 (2025) 136502
Abstract:
The band-projected density operators in a Landau level obey the Girvin-MacDonald-Platzman (GMP) algebra, and a large amount of effort in the study of fractional Chern insulators has been directed toward approximating this algebra in a Chern band. In this Letter, we prove that the GMP algebra, up to form factors, is the only closed algebra that projected density operators can satisfy in two and three dimensions, highlighting the central place it occupies in the study of Chern bands in general. A number of interesting corollaries follow.