Extended staggered-flux phases in two-dimensional lattices

Based on the so called $t$-$\phi$ model in two-dimensional (2D) lattices, we investigate the stabilities of a class of extended staggered-flux (SF) phases (which are the extensions of the $\sqrt{2}\times\sqrt{2}$ SF phase to generalized spatial periods) against the Fermi-liquid phase. Surprisingly, when away from the nesting electron filling, some extended-SF phases take over the dominant SF phase (the $\sqrt{2}\times\sqrt{2}$ SF phase for the square lattice, a $1\times\sqrt{3}$ SF phase for the triangular one), compete with the Fermi-liquid phase in nontrivial patterns, and still occupy significant space in the phase diagram through the advantage in the total electronic kinetic energies. The results can be termed as the generalized Perierls orbital-antiferromagnetic instabilities of the Fermi-liquid phase in 2D lattice-electron models.Comment: 5 pages, 5 figure

Modelling carbon-chain species formation in lukewarm corinos with new multi-phase models

Abundant carbon-chain species have been observed towards lukewarm corinos L1527, B228, and L483. These carbon-chain species are believed to be synthesized in the gas phase after CH$_4$ desorbs from the dust grain surface at the temperature around 30 K. We investigate carbon-chain species formation in lukewarm corinos using a more rigorous numerical method and advanced surface chemical models. We use the macroscopic Monte Carlo method in simulations. In addition to the two-phase model, the basic multiphase model and the new multiphase models are used for modeling surface chemistry on dust grains. All volatile species can sublime at their sublimation temperatures in the two-phase model while most volatile species are frozen in the ice mantle before water ice sublimes in the basic and the new multiphase models. The new multiphase models allow more volatile species to sublime at their sublimation temperatures than the basic multiphase model does. When T $\sim$ 30 K, the abundances of gaseous CH$_4$ and CO in the two-phase model are the highest while the basic multiphase model predicts the lowest CO and CH$_4$ abundances among all models. The abundances of carbon-chain species in the basic and the new multiphase models are lower than that in the two-phase model when T $\sim$ 30 K because CH$_4$ is crucial for the synthesis of carbon-chain species. The two-phase model performs the best to predict carbon-chain species abundances to fit observations while the basic multiphase model works the worst. The abundances of carbon-chain species predicted by the new multiphase models agree reasonably well with observations. The amount of CH$_4$ that can diffuse inside the ice mantle, thus sublime upon warm-up plays a crucial role in the synthesis of carbon-chain species in the gas phase. The carbon-chain species observed in lukewarm corinos may be able to gauge surface chemical models

Distributionally Robust Semi-Supervised Learning for People-Centric Sensing

Semi-supervised learning is crucial for alleviating labelling burdens in people-centric sensing. However, human-generated data inherently suffer from distribution shift in semi-supervised learning due to the diverse biological conditions and behavior patterns of humans. To address this problem, we propose a generic distributionally robust model for semi-supervised learning on distributionally shifted data. Considering both the discrepancy and the consistency between the labeled data and the unlabeled data, we learn the latent features that reduce person-specific discrepancy and preserve task-specific consistency. We evaluate our model in a variety of people-centric recognition tasks on real-world datasets, including intention recognition, activity recognition, muscular movement recognition and gesture recognition. The experiment results demonstrate that the proposed model outperforms the state-of-the-art methods.Comment: 8 pages, accepted by AAAI201

Fractional Quantum Hall Effect in Topological Flat Bands with Chern Number Two

Recent theoretical works have demonstrated various robust Abelian and non-Abelian fractional topological phases in lattice models with topological flat bands carrying Chern number C=1. Here we study hard-core bosons and interacting fermions in a three-band triangular-lattice model with the lowest topological flat band of Chern number C=2. We find convincing numerical evidence of bosonic fractional quantum Hall effect at the $\nu=1/3$ filling characterized by three-fold quasi-degeneracy of ground states on a torus, a fractional Chern number for each ground state, a robust spectrum gap, and a gap in quasihole excitation spectrum. We also observe numerical evidence of a robust fermionic fractional quantum Hall effect for spinless fermions at the $\nu=1/5$ filling with short-range interactions.Comment: 5 pages, 7 figures, with Supplementary Materia

Non-Abelian Quantum Hall Effect in Topological Flat Bands

Inspired by recent theoretical discovery of robust fractional topological phases without a magnetic field, we search for the non-Abelian quantum Hall effect (NA-QHE) in lattice models with topological flat bands (TFBs). Through extensive numerical studies on the Haldane model with three-body hard-core bosons loaded into a TFB, we find convincing numerical evidence of a stable $\nu=1$ bosonic NA-QHE, with the characteristic three-fold quasi-degeneracy of ground states on a torus, a quantized Chern number, and a robust spectrum gap. Moreover, the spectrum for two-quasihole states also shows a finite energy gap, with the number of states in the lower energy sector satisfying the same counting rule as the Moore-Read Pfaffian state.Comment: 5 pages, 7 figure