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The rapid development of moir\'e quantum matter has recently led to the remarkable discovery of the fractional quantum anomalous Hall effect, and sparked predictions of other novel correlation-driven topological states. Here, we investigate the interplay of electronic crystals with integer and fractional Chern insulators in a moir\'e lattice of rhomobohedral pentalayer graphene (RPG) aligned with hexagonal boron nitride. At a doping of one electron per moir\'e unit cell, we see a correlated insulator with a Chern number that can be tuned between $C=0$ and $+1$ by an electric displacement field, accompanied by an array of other such insulators formed at fractional band fillings, $\nu$. Collectively, these states likely correspond to trivial and topological electronic crystals, some of which spontaneously break the discrete translational symmetry of the moir\'e lattice. Upon applying a modest magnetic field, a narrow region forms around $\nu=2/3$ in which transport measurements imply the emergence of a fractional Chern insulator, along with hints of weaker states at other fractional $\nu$. In the same sample, we also see a unique sequence of incipient Chern insulators arising over a broad range of incommensurate band filling near two holes per moir\'e unit cell. Our results establish moir\'e RPG as a fertile platform for studying the competition and potential intertwining of electronic crystallization and topological charge fractionalization., Comment: 8 pages, 4 figures, extended data, 10 extended data figures, 13 supplementary information figures

In a dilute two-dimensional electron gas, Coulomb interactions can stabilize the formation of a Wigner crystal. Although Wigner crystals are topologically trivial, it has been predicted that electrons in a partially-filled band can break continuous translational symmetry and time-reversal symmetry spontaneously to form an anomalous Hall crystal (AHC). Here, we report the observation of a generalized AHC in twisted bilayer-trilayer graphene whose formation is seeded by the moire potential. The crystal quadruples the moire unit-cell area, coinciding with an integer quantum anomalous Hall effect. The Chern number of the state is exceptionally tunable, and can be switched reversibly between +1 and -1 by electric and magnetic fields. Recent theories have predicted the generalized AHC to act as a parent state of the fractional quantum anomalous Hall effect, pointing to twisted bilayer-trilayer graphene as a promising platform in the search for new correlated and topological phenomena.

Recent observations of an 80 K superconductor in La$_3$Ni$_2$O$_7$ under high pressure have attracted significant attention. Recent experiments indicate that La$_3$Ni$_2$O$_7$ may be in the charge transfer regime, challenging the previous models based purely on the Ni $d_{x^2-y^2}$ and $d_{z^2}$ orbitals. In this study, we propose a low energy model that incorporates doped holes in the oxygen $p$ orbitals. Given that the parent nickel state is in the $3d^{8}$ configuration with a spin-one moment, doped hole only screens it down to spin-half, in contrast to the Zhang-Rice singlet in cuprate. We dub the single hole state as Zhang-Rice spin-half and build an effective model which includes three spin-one states ($d^8$) and two Zhang-Rice spin-half states ($d^8 L$). At moderate pressure around $20$ GPa, the dominated oxygen orbital is an in-plane Wannier orbital with the same lattice symmetry as the $d_{x^2-y^2}$ orbital. The resulting model reduces to the bilayer type II t-J model previously proposed in the Mott-Hubbard regime. Notably, the hopping between the in-plane $p$ orbitals of the two layers is still suppressed. Density matrix renormalization group (DMRG) simulation reveals a pairing dome with the optimal hole doping level at $x=0.4\sim0.5$, distinct from the hole doped cuprate where optimal doping occurs around $x=0.19$. Further increasing pressure initially raises the critical temperature ($T_c$) until reaching an optimal pressure beyond which the $p_z$ orbital of oxygen becomes favorable and superconductivity is diminished. This shift from in-plane $p$ orbital to $p_z$ orbital may elucidate the experimentally observed superconducting dome with varying pressure. As an extension, we also suggest a trilayer version of the type II t-J model as the minimal model for pressured La$_4$Ni$_3$O$_{10}$, which is distinct from the models in the Mott-Hubbard regime., Comment: 7+10 pages, 3+9 figures, 0+1 table

This study aims to evaluate the functional status of bilateral neurovascular bundles (NVBs) using pulsed wave Doppler ultrasound in patients undergoing prostate radiotherapy (RT). Sixty-two patients (mean age: 66.1 +/- 7.2 years) underwent transrectal ultrasound scan using a conventional ultrasound scanner, a 7.5 MHz bi-plane probe and a mechanical stepper. The ultrasound protocol comprised 3 steps: 1) 3D B-mode scans of the entire prostate, 2) localization of NVBs using color flow Doppler imaging, and 3) measurement of NVB function using pulsed wave Doppler. Five pulsed Doppler waveform features were extracted: peak systolic velocity (PSV), end-diastolic velocity (EDV), mean velocity (Vm), resistive index (RI), and pulsatile index (PI). In summary, this study presents a Doppler evaluation of NVBs in patients undergoing prostate RT. It highlights substantial differences in Doppler ultrasound waveform features between bilateral NVBs. The proposed ultrasound method may prove valuable as clinicians strive to deliver NVB-sparing RT to preserve sexual function effectively and enhance patients' overall well-being., Comment: 14 pages, 4 figures

The standard theoretical framework for fractional quantum anomalous Hall effect (FQAH) assumes an isolated flat Chern band in the single particle level. In this paper we challenges this paradigm for the FQAH recently observed in the pentalayer rhombohedral stacked graphene aligned with hexagon boron nitride (hBN). We show that the external moir\'e superlattice potential is simply a perturbation in a model with continuous translation symmetry. Through Hartree Fock calculation, we find that interaction opens a sizable remote band gap, resulting an isolated narrow $C=1$ Chern band at filling $\nu=1$. From exact diagonalization (ED) we identify FQAH phases at various fillings. But they exist also in the calculations without any external moir\'e potential. We suggest that the QAH insulator at $\nu=1$ should be viewed as an interaction driven topological Wigner crystal with QAH effect, which is then pinned by a small moir\'e potential. The $C=1$ QAH crystal is robust with a crystal period around $10\mathrm{nm}$ in 4-layer, 5-layer, 6-layer and 7-layer graphene systems. Our work suggests a new direction to exploring the interplay of topology and FQAH with spontaneous crystal formation in the vanishing moir\'e potential limit. We also propose a new system to generate and control both honeycomb and triangular moir\'e superlattice potential through Coulomb interaction from another control layer, which can stabilize or suppress the QAH crystal depending on the density of the control layer., Comment: 10 pages, 9 figures

Weak Mott regime with finite U is a wonderful region to search for quantum spin liquid, but it is challenging to write down a wavefunction capturing both spin liquid and charge fluctuations. Conventional methods using complicated Jastrow factors have difficulties when the underlying spin liquid has a non-trivial projective symmetry group (PSG). To cure this problem, here we provide a new class wavefunction for Mott insulator through quantum teleportation using ancilla qubits. We primarily focus on half filling of the fermionic Hubbard model. We will prove that a single variation parameter $\Phi$ in our wavefunction tunes the Mott charge gap continuously. On a generic lattice, we show that the wavefunction at $\Phi=+\infty$ recovers the familiar Gutzwiller projectived wavefunction at infinite U. The wavefunction at $\Phi=\frac{U}{2}$ is equivalent to applying the inverse Schrieffer Wolff transformation at linear order of $t/U$, as expected in large but finite U regime. From a gauge theory description we can show that the wavefunction has an electronic sector decoupled from a spinon sector describing localized spin moments. The charge gap $\Delta_c$ can be shown to be $2\Phi$ and we conjecture that the wavefunction works well down to the regime with small charge gap on a generic lattice. We represent the wavefunction using tensor network and numerically confirm this conjecture in one dimension. Beyond the numerical power, the ancilla wavefunction also provides a new conceptual picture to understand the bandwidth tuned metal insulator transition. In this new framework, there can in principle exist a narrow region of fractional Fermi liquid (FL*) phase between the usual Fermi liquid and the Mott insulator, a scenario which is not captured by the conventional slave rotor theory and thus was usually outlooked., Comment: 11 pages, 6 figures

In this paper, we derive lattice models for the narrow moir\'e bands of the AB-stacked twisted WSe$_2$ homobilayer through continuum model and Wannier orbital construction. Previous work has shown that an approximate SU(4) Hubbard model may be realized by combining spin and layer because inter-layer tunneling is suppressed due to spin $S_z$ conservation. However, Rashba spin-orbit coupling (SOC) was ignored in the previous analysis. Here, we show that a Rashba SOC of reasonable magnitude can induce a finite but very small inter-layer hopping in the final lattice Hubbard model. At total filling $n=1$, we derive a spin-layer model on a triangular lattice in the large-U limit where the inter-layer tunneling contributes as a sublattice-dependent transverse Ising field for the layer pseudospin. We then show that the $n=2$ Mott insulator is also captured by an approximate SU(4) spin model, but now on honeycomb lattice. We comment on the possibility of a Dirac spin liquid (DSL) and competing phases due to SU(4) anisotropy terms.

Recent experimental progresses have made it possible to simulate spin 1/2 Hubbard model on triangular lattice in moir\'e materials formed by transition metal dichalcogenide (TMD) heterobilayer or homobilayer. In twisted TMD homobilayer, a vertical electric field can induce a valley contrasting flux in the hopping term. In this paper we study possible superconductors from a t-J model with valley contrasting flux $\Phi$ using the slave boson mean field theory. We obtain a phase diagram with doping $x$ and $\Phi$. A finite $\Phi$ breaks spin rotation symmetry and the pairing symmetry is a superposition of spin singlet $d-id$ and spin triplet $p+ip$. There are two topological phase transitions when tuning $\Phi$ from $0$ to $\pi$, with three Dirac nodes at one transition and one single Dirac node at the other transition. We also discuss the effects of van Hove singularity and a three-site correlated hopping term on the pairing strength. Lastly, we demonstrate that a small anisotropy term breaking the $C_3$ rotation can lead to a time reversal invariant nodal superconductor connected to the $d_{x^2-y^2}$ superconductor on square lattice.

Critical transition points between symmetry-broken phases are characterized as fixed points in the renormalization group (RG) theory. We show that, following the standard Wilsonian procedure that traces out the large momentum modes, this well known fact can break down in non-Hermitian systems. Based on non-Hermitian Su-Schrieffer-Hegger (SSH)-type models, we propose a real-space decimation scheme to study the criticality between the topological and trivial phase. We provide concrete examples and an analytic proof to show that the real-space scheme perfectly overcomes the insufficiency of the standard method, especially in the sense that it always preserves the system at criticality as fixed points under RG. The proposed method can also greatly simplify the search of critical points for complicated non-Hermitian models by ruling out the irrelevant operators. These results pave the way towards more advanced RG-based techniques for the interacting non-Hermitian quantum systems.

Quantitative ultrasound (QUS) imaging is a reliable, fast and inexpensive technique to extract physically descriptive parameters for assessing pathologies. Despite its safety and efficacy, QUS suffers from several major drawbacks: poor imaging quality, inter- and intra-observer variability which hampers the reproducibility of measurements. Therefore, it is in great need to develop automatic method to improve the imaging quality and aid in measurements in QUS. In recent years, there has been an increasing interest in artificial intelligence (AI) applications in ultrasound imaging. However, no research has been found that surveyed the AI use in QUS. The purpose of this paper is to review recent research into the AI applications in QUS. This review first introduces the AI workflow, and then discusses the various AI applications in QUS. Finally, challenges and future potential AI applications in QUS are discussed., Comment: 35 pages, 2 figures

Lung ultrasound surface wave elastography (LUSWE) is a novel noninvasive technique for measuring superficial lung tissue stiffness.The purpose of this study was to translate LUSWE for assessing patients with interstitial lung disease (ILD) and various connective diseases including systemic sclerosis (SSc).In this study, LUSWE was used to measure the surface wave speed of lung at 100 Hz, 150 Hz and 200 Hz through six intercostal lung spaces for 91 patients with ILD and 30 healthy control subjects. In addition, skin viscoelasticity was measured at both forearms and upper arms for patients and controls. The surface wave speeds of patients' lungs were significantly higher than those of control subjects for the six intercostal spaces and the three excitation frequencies. Patient skin elasticity and viscosity were significantly higher than those of control subjects for the four locations on the arm. In dividing ILD patients into two groups, ILD patients with SSc and ILD patients without SSc, significant differences between each patient group with the control group were found for both the lung and skin.No significant differences were found between the two patients group, although there were some differences at a few locations and at 100 Hz. LUSWE may be useful for assessing ILD and SSc and screening early stage patients., Comment: 11 pages, 5 figures

The objective of this study was to investigate the relationship between erectile pressure (EP) and shear wave speed of the corpus cavernosa obtained via a specific ultrasound vibro-elastography (UVE) technique. This study builds upon our prior investigation, in which UVE was used to evaluate the viscoelastic properties of the corpus cavernosa in the flaccid and erect states. A two-dimensional poroviscoelastic finite element model (FEM) was developed to simulate wave propagation in the penile tissue according to our experimental setup. Various levels of EP were applied to the corpus cavernosa, and the relationship between shear wave speed in the corpus cavernosa and EP was investigated. Results demonstrated non-linear, positive correlations between shear wave speeds in the corpus cavernosa and increasing EP at different vibration frequencies (100-200 Hz). These findings represent the first report of the impact of EP on shear wave speed and validates the use of UVE in the evaluation of men with erectile dysfunction. Further evaluations are warranted to determine the clinical utility of this instrument in the diagnosis and treatment of men with erectile dysfunction., Comment: 18 pages, 5 figures. 1 table

Pleural effusion manifested as compression of pleural fluid on the lung parenchyma, contributing to hypoxemia. Medical procedure such as drainage of plural fluid releases this compression and increase the oxygenation. However, the effect of pleural effusion on the elasticity of lung parenchyma is unknown. By using the lung ultrasound surface wave elastography (LUSWE) and finite element method (FEM), the effect of pleural effusion on the elasticity of superficial lung parenchyma in terms of surface wave speed measurement was evaluated in a sponge phantom study. Different thickness of ultrasound transmission gel simulated as pleural fluid was inserted into a condom which was placed between the sponge and standoff pad. A mechanical shaker was used to generate vibration on the sponge phantom at different frequencies ranging from 100 to 300 Hz while ultrasound transducer was used to capture the motion for measurement of surface wave speed of the sponge. FEM was conducted based on the experimental setup and numerically assess the influence of pleural effusion on the surface wave speed of the sponge. We found the influence of thickness of ultrasound transmission gel was statistically insignificant on the surface wave speed of the sponge at 100 and 150 Hz both from experiments the FEM., Comment: 20 pages, 6 figures, 1 table