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The interplay between strong electron-electron interaction and symmetry breaking can have profound influence on the topological properties of materials. In magic angle twisted bilayer graphene (MATBG), the flat band with a single SU(4) flavor associated with the spin and valley degrees of freedom gains non-zero Chern number when C2z symmetry or C2zT symmetry is broken. Electron-electron interaction can further lift the SU(4) degeneracy, leading to the Chern insulator states. Here we report a complete sequence of zero-field Chern insulators at all odd integer fillings (v = +-1, +-3) with different chirality (C = 1 or -1) in hBN aligned MATBG which structurally breaks C2z symmetry. The Chern states at hole fillings (v = -1, -3), which are firstly observed in this work, host an opposite chirality compared with the electron filling scenario. By slightly doping the v = +-3 states, we have observed new correlated insulating states at incommensurate moir\'e fillings which is highly suggested to be intrinsic Wigner crystals according to our theoretical calculations. Remarkably, we have observed prominent Streda-formula violation around v = -3 state. By doping the Chern gap at v = -3 with notable number of electrons at finite magnetic field, the Hall resistance Ryx robustly quantizes to ~ h/e2 whereas longitudinal resistance Rxx vanishes, indicating that the chemical potential is pinned within a Chern gap, forming an incommensurate Chern insulator. By providing the first experimental observation of zero-field Chern insulators in the flat valence band, our work fills up the overall topological framework of MATBG with broken C2z symmetry. Our findings also demonstrate that doped topological flat band is an ideal platform to investigate exotic incommensurate correlated topological states., Comment: 28 pages. 5 figures

Evidence suggests that different prompts lead large language models (LLMs) to generate responses with varying quality. Yet, little is known about prompts' effects on response quality in healthcare domains. In this exploratory study, we address this gap, focusing on a specific healthcare domain: dementia caregiving. We first developed an innovative prompt template with three components: (1) system prompts (SPs) featuring 4 different roles; (2) an initialization prompt; and (3) task prompts (TPs) specifying different levels of details, totaling 12 prompt combinations. Next, we selected 3 social media posts containing complicated, real-world questions about dementia caregivers' challenges in 3 areas: memory loss and confusion, aggression, and driving. We then entered these posts into GPT-4, with our 12 prompts, to generate 12 responses per post, totaling 36 responses. We compared the word count of the 36 responses to explore potential differences in response length. Two experienced dementia care clinicians on our team assessed the response quality using a rating scale with 5 quality indicators: factual, interpretation, application, synthesis, and comprehensiveness (scoring range: 0-5; higher scores indicate higher quality).

The experimental discoveries of fractional quantum anomalous Hall effects under zero magnetic fields in both transition metal dichalcogenide and pentalayer graphene moir\'e superlattices have aroused significant research interest. In this work, we theoretically study the fractional quantum anomalous Hall states (also known as fractional Chern insulator states) in pentalayer graphene moir\'e superlattice. Starting from the highest energy scale ($\sim\!2\,$eV) of the continuum model, we first construct a renormalized low-energy model that applies to a lower cutoff $\sim\!0.15\,$eV using renormalization group approach. Then, we study the ground states of the renormalized low-energy model at filling 1 under Hartree-Fock approximation in the presence of tunable but self-consistently screened displacement field $D$ with several experimentally relevant background dielectric constant $\epsilon_r$. Two competing Hartree-Fock states are obtained at filling 1, which give rise to two types of topologically distinct isolated flat bands with Chern number 1 and 0, respectively. We continue to explore the interacting ground states of the two types of isolated flat bands at hole dopings of 1/3, 2/5, 3/5, and 2/3 (corresponding electron fillings of 2/3, 3/5, 2/5, and 1/3 with respect to charge neutrality). Setting $\epsilon_r=5$, our exact-diagonalization calculations suggest that the system stays in fractional Chern insulator (FCI) state at 2/3 electron filling when $0.9\,\textrm{V/nm}\leq\!D\!\leq 0.92\,\textrm{V/nm}$; while no robust FCI state is obtained at 1/3 electron filling. We have also obtained composite-fermion type FCI ground states at 3/5 electron filling within $0.9\,\textrm{V/nm}\leq\! D \!\leq\!0.95\,\textrm{V/nm}$ and $\epsilon_r=5$. These numerical results are quantitatively consistent with experimental observations., Comment: 12 pages + 6 figures + 1 table in main text, 21 pages + 12 figures in Supplementary Information. More comprehensive phase diagrams are provided

Twisted bilayer graphene (TBG) and other quasi-two-dimensional moir\'e superlattices have attracted significant attention due to the emergence of various correlated and topological states associated with the flat bands in these systems. In this work, we theoretically explore the physical properties of a new type of \textit{three dimensional graphite moir\'e superlattice}, the bulk alternating twisted graphite (ATG) system with homogeneous twist angle, which is grown by in situ chemical vapor decomposition method. Compared to TBG, the bulk ATG system is bestowed with an additional wavevector degrees of freedom due to the extra dimensionality. As a result, we find that when the twist angle of bulk ATG is smaller than twice of the magic angle of TBG, there always exist ``magic momenta" at which the in-plane Fermi velocities of the moir\'e bands vanish. Moreover, topologically distinct flat bands of TBG at different magic angles can even co-exist at different out-of-plane wavevectors in a single bulk ATG system. Most saliently, when the twist angle is relatively large, exactly dispersionless three dimensional zeroth Landau level would emerge in the bulk ATG, which may give rise to robust three dimensional quantum Hall effects over a large range of twist angles., Comment: 6 pages + 3 figures in main text, 17 pages + 13 figures in Supplementary Information

The CoachAI Badminton 2023 Track1 initiative aim to automatically detect events within badminton match videos. Detecting small objects, especially the shuttlecock, is of quite importance and demands high precision within the challenge. Such detection is crucial for tasks like hit count, hitting time, and hitting location. However, even after revising the well-regarded shuttlecock detecting model, TrackNet, our object detection models still fall short of the desired accuracy. To address this issue, we've implemented various deep learning methods to tackle the problems arising from noisy detectied data, leveraging diverse data types to improve precision. In this report, we detail the detection model modifications we've made and our approach to the 11 tasks. Notably, our system garnered a score of 0.78 out of 1.0 in the challenge. We have released our source code in Github https://github.com/jean50621/Badminton_Challenge, Comment: Golden Award for IJCAI CoachAI Challenge 2023: Team NTNUEE AIoTLab

In this work, we present a theoretical research on the lattice relaxations, phonon properties, and relaxed electronic structures in magic-angle twisted bilayer graphene (TBG). We construct a continuum elastic model in order to study the lattice dynamics of magic-angle TBG, where both in-plane and out-of-plane lattice displacements are take into account. The fully relaxed lattice structure calculated using such a model is in quantitative agreement with experimental measurements. Furthermore, we investigate the phonon properties in magic-angle TBG using the continuum elastic model, where both the in-plane and out-of-plane phonon modes are included and treated on equal footing. We identify different types of moir\'e phonons including in-plane sliding modes, soft out-of-plane flexural modes, as well as out-of-plane breathing modes. The latter two types of phonon modes exhibit interesting monopolar, dipolar, quadrupolar, and octupolar-type out-of-plane vibration patterns. Additionally, we explore the impact of the relaxed moir\'e superlattice structure on the electronic band structures of magic-angle TBG using an effective continuum model, which shows nearly exact agreement with those calculated using a microscopic atomistic tight-binding approach. Our work lays foundation for further studies on the electron-phonon coupling effects and their interplay with $e$-$e$ interactions in magic-angle TBG., Comment: 14+16 pages, 6 figures

Studying strong electron correlations has been an essential driving force for pushing the frontiers of condensed matter physics. In particular, in the vicinity of correlation-driven quantum phase transitions (QPTs), quantum critical fluctuations of multiple degrees of freedom facilitate exotic many-body states and quantum critical behaviors beyond Landau's framework. Recently, moir\'e heterostructures of van der Waals materials have been demonstrated as a highly tunable quantum platform for exploring fascinating strongly correlated quantum physics. Here, we report the observation of tunable quantum criticalities in an experimental simulator of extended Hubbard model with spin-valley isospins arising in chiral-stacked twisted double bilayer graphene. Scaling analysis shows a quantum two-stage criticality manifesting two distinct quantum critical points as the generalized Wigner crystal transits to a Fermi liquid by varying the displacement field, suggesting the emergence of a critical intermediate phase. The quantum two-stage criticality evolves into a quantum pseudo criticality as a high parallel magnetic field is applied. In such pseudo criticality, we find that the quantum critical scaling is only valid above a critical temperature, indicating a weak first-order QPT therein. Our results demonstrate a highly tunable solid-state simulator with intricate interplay of multiple degrees of freedom for exploring exotic quantum critical states and behaviors., Comment: https://www.nature.com/articles/s41586-022-05106-0

Entropic uncertainty relation (EUR) formulates the restriction of the inherent uncertainty of quantum mechanics from the information-theoretic perspective. A tighter lower bound for uncertainty relations can provide information-theoretic security to quantum communication protocols. Recently, a generalized EUR (GEUR) for the measurement of multiple observables in arbitrary many-body systems has been formulated. Here, we experimentally test this GEUR using a four-photon entangled state with a controllable decoherence channel and show that for the tripartite scenario, the GEUR improves the entropic bound from Renes--Boileau's famous results. As an application, we further demonstrate an improvement of the secure key rate in quantum key distribution from the GEUR. Our results extend the test of EURs into multipartite regimes and may find applications in practical quantum cryptography tasks., Comment: 6 pages, 4 figures, comments are welcomed

Recently, an entropic uncertainty relation for multiple measurements has been proposed by Liu et al. in [Phys. Rev. A 91, 042133 (2015)]. However, the lower bound of the relation is not always tight with respect to different measurements. Herein, we improve the lower bound of the entropic uncertainty relation for multiple measurements, termed as simply constructed bound (SCB). We verify that the SCB is tighter than Liu et al.'s result for arbitrary mutually unbiased basis measurements, which might play a fundamental and crucial role in practical quantum information processing. Moreover, we optimize the SCB by considering mutual information and the Holevo quantity, and propose an optimized SCB (OSCB). Notably, the proposed bounds are extrapolations of the behavior of two measurements to a larger collection of measurements. It is believed that our findings would shed light on entropy-based uncertainty relations in the multiple measurement scenario and will be beneficial for security analysis in quantum key distributions., Comment: 7 pages, 4 figures

Twisted graphene systems have draw significant attention due to the discoveries of various correlated and topological phases. In particular, recently the alternating twisted trilayer graphene is discovered to exhibit unconventional superconductivity, which motivates us to study the electronic structures and possible interesting correlation effects of this class of alternating twisted graphene systems. In this work we consider generic alternating twisted multilayer graphene (ATMG) systems with $M$-$L$-$N$ stacking configurations, in which the $M$ ($L$) graphene layers and the $L$ ($N$) layers are twisted by an angle $\theta$ (-$\theta$). Based on analysis from a simplified $\textbf{k}\!\cdot\!\textbf{p}$ model approach, we analytically derive generic partition rules for the low-energy electronic structures, which exhibit various intriguing band dispersions including one pair of flat bands, two pairs of flat bands, as well as flat bands co-existing with with Dirac cones, quadratic bands, or more generally $E(\mathbf{k})\!\sim\!k^J$ dispersions ($J$ is positive integer) for each spin and valley. Such unusual non-interacting electronic structures may have unconventional correlation effects. Especially for a mirror symmetric ATMG system with two pairs of flat bands (per spin per valley), we find that Coulomb interactions may drive the system into a state breaking both time-reversal and mirror symmetries, which can exhibit a novel type of orbital magnetoelectric effect due to the interwining of electric polarization and orbital magnetization orders in the symmetry-breaking state.