Fock-state lattice (FSL) offers a powerful quantum simulator for topological phenomena due to the unbounded scalability and ease of implementation. Nevertheless, the unique topological properties induced by its site-dependent coupling have remained elusive, mainly due to the challenge of handling an infinite state space without translational symmetry. Here, we rigorously analyze the topological features of a semi-infinite FSL-based Su-Schrieffer-Heeger (SSH) model, in both Hermitian and non-Hermitian realms, by mapping it to the solvable Jaynes-Cummings model via a unitary displacement transformation. We find a topological zero mode persisting across all parameter regimes, which is more stable than the conventional SSH model. It originates from the bound state at the inherent domain wall under anisotropic conditions. With gain and loss introduced, we predict a non-Hermitian bound effect, i.e., any state overlapping with the bound state will quickly stabilize to the domain wall, with the minimal stabilization time occurring in the vicinity of exceptional point. The parity-time phase transition can be observed by the oscillating-to-steady crossover of dynamics in the subspace orthogonal to the bound state. Furthermore, a concrete experimental proposal based on the trapped-ion setup is provided.

Controlling photon-mediated energy flow is central to the future of communications, thermal management, and energy harvesting technologies. Recent breakthroughs have revealed that many-body systems violating Lorentz reciprocity can sustain persistent photon heat current at thermal equilibrium, hinting at a paradigm of heat flow akin to superconductivity. Yet, the behavior of such systems far from equilibrium remains largely unexplored. In this work, we uncover the rich physics of radiative heat transfer in nonequilibrium, far-field many-body systems composed of thermal emitters that break Lorentz reciprocity. We show that the total heat flow naturally decomposes into two distinct components: an equilibrium term, which generates a persistent circulating heat current within the system, and a nonequilibrium term, which governs energy exchange with the environment. Remarkably, while the internal persistent heat current is ever-present, the nonequilibrium contribution can be precisely engineered to achieve perfect heat rectification and circulation. Our results open a route toward designing thermal systems with unprecedented control—unlocking the potential for lossless heat circulation and one-way thermal devices. This fundamentally shifts the landscape for next-generation thermal logic, energy conversion, and photonic heat engines.

We theoretically investigate the magnetic-multipole orders in two-dimensional (2D) altermagnets, focusing on two representative models: a generic minimal three-site model and a four-site model representative of monolayer FeSe. We construct low-energy effective Hamiltonians for both systems and calculate their respective multipole indicators to characterize the underlying magnetic order. Our analysis reveals an intriguing contrast between the two systems. We find that the generic minimal model exhibits the expected nonzero magnetic-octupole order. In the monolayer-FeSe model, however, the magnetic-octupole order vanishes globally, and a magnetic-hexadecapole order is present instead. The emergence of altermagnetic splitting in the band structure then arises via the interplay with a sublattice-isospin degree of freedom. Our work demonstrates how the classification and comprehensive understanding of 2D altermagnetic materials transcends bulk descriptions.

$\mathrm{La}{\mathrm{I}}_3$ has emerged as a promising scintillator due to its relatively small band gap. While some studies have explored various dopants to enhance its performance, there remains significant room for optimization, highlighting the importance of further understanding and tuning the intrinsic characteristics of $\mathrm{La}{\mathrm{I}}_3$. In this work, the crystal structure and properties of $\mathrm{La}{\mathrm{I}}_3$ are extensively investigated under high pressure up to 50 GPa. The ambient layered Cmcm-$\mathrm{La}{\mathrm{I}}_3$ is found to undergo an unexpected isostructural phase transition at ∼11 GPa, characterized by an anomalous change in the ratio of the $a$ to $b$ lattice parameters. This transition is further supported by Raman spectroscopy, electrical transport measurements, and first-principles calculations. Additionally, ultraviolet-visible absorption experiments indicate that the band gap of $\mathrm{La}{\mathrm{I}}_3$ gradually narrows and tends toward closure, eventually leading to a metallic state at 37 GPa. This work uncovers an interesting second-order phase transition among lanthanide halides, providing new insights into the fundamental behavior of $\mathrm{La}{\mathrm{I}}_3$ under high pressure.

The topological characteristics of energy bands in crystalline systems are encapsulated in the Berry curvature of the bulk Bloch states. In photonic crystal slabs, far-field emission from guided resonances naturally provides a noninvasive way to probe the embedded wavefunctions, raising the question of how the information carried by escaping photons relates to the band topology. We develop a non-Hermitian model to describe the guided and leaky modes of photonic crystal slabs with long-range couplings and non-local responses. Within this framework, radiation Berry curvature is defined from the far-field polarization and compared to the conventional bulk Berry curvature of the crystal Bloch modes. We investigate this bulk-radiation correspondence in the vicinity of the $\mathrm{\Gamma }$ point of the square lattice and the $K$ point of the honeycomb lattice. The results show that the comparability between the bulk topology and the radiation topology is not universal; the validity is contingent upon the specific bulk Bloch states. Notably, the correspondence completely breaks down surrounding the far-field singularities, while it can hold in smooth regions under special symmetry conditions, e.g., inversion symmetry. Besides, net Berry curvature concentration is captured at the valleys of the nonlocal honeycomb lattice, facilitating further exploration on generalized topological phases in photonic lattices beyond the regimes with localized couplings and Hermiticity.

Chromium trihalides $\mathrm{Cr}{X}_3$ ($X=\text{Cl}$, Br, and I) have recently become a focal point of research due to their intriguing low-temperature, layer-dependent magnetic properties that can be manipulated by external stimuli. This makes them essential candidates for spintronic applications. Their magnetic orders are often related to the electronic structure parameters, such as spin-orbit coupling (SOC), Hund’s coupling ($J_H$), $p-d$ covalency, and interorbital Coulomb interactions. Accurately determining such parameters is paramount for understanding $\mathrm{Cr}{X}_3$ physics. We have used high-resolution resonant inelastic x-ray scattering spectroscopy to study $\mathrm{Cr}{X}_3$ across phase transition temperatures. Ligand field multiplet calculations were used to determine the electronic structure parameters by incorporating the crystal field interactions in a distorted octahedral orientation with $C_3$ symmetry. These methods provide the most detailed description of $\mathrm{Cr}{X}_3$ magneto-optical and electronic (energetic) terms to date. The crystal field distortion parameters $D\sigma$ and $D\tau$ were experimentally determined, and the energies of $d$ orbitals have been reported. The spectroscopic measurements reveal an energy separation between spin-allowed quartet states and spin-forbidden doublet states, which increases upon going from ${\mathrm{CrCl}}_3$ to ${\mathrm{CrI}}_3$. The role of SOC, for Cr $2p$ orbitals, in spin-flip excitations has been demonstrated. The determined $10Dq$ values are in good agreement with the spectrochemical series, and Racah $B$ follows the nephelauxetic effect. Such precise measurements offer insights into the energy design of spintronic devices that utilize quantum state tuning within two-dimensional magnetic materials.

The Mott insulator α$\text{−}\mathrm{RuC}{\mathrm{l}}_3$, featuring the intertwined interplay of spin-orbit coupling and Kitaev spin correlations, provides an unparalleled platform for probing quantum many-body physics. Using scanning tunneling microscopy/spectroscopy, we compare temperature-dependent $\mathit{dI}/\mathit{dV}$ spectra between in situ grown monolayers and exfoliated bulk samples. Both systems exhibit pronounced Mott gap softening near 110 K, manifested by spectral weight transfer from Hubbard bands toward the Fermi level, resulting in low-energy correlated charge delocalization. Although this gap softening coincides with Kitaev paramagnetic and structural phase transitions in bulk crystals, monolayer studies provide compelling insights. By eliminating structural phase transition in monolayer sample, we suggest that spin correlations, rather than Coulomb interactions alone, may govern charge dynamics within the Mott-Hubbard framework, challenging conventional Mott-Hubbard paradigms. These results resolve a long-standing controversy regarding the Mott gap magnitude in α$\text{−}\mathrm{RuC}{\mathrm{l}}_3$ and experimentally confirm the critical role of spin correlations in Mott physics.

Quantum computation with electron spin qubits requires coherent and efficient manipulation of these spins, typically accomplished through the application of alternating magnetic or electric fields for electron spin resonance. In particular, electrical driving allows us to apply localized fields on the electrons, which benefits scale-up architectures. However, we have found that Electric Dipole Spin Resonance is insufficient for modeling the Rabi behavior in recent experimental studies. Therefore, we propose that the electron spin is being driven by a method of electric spin qubit control that generalizes the spin dynamics by taking into account a quadrupolar contribution of the quantum dot: electric quadrupole spin resonance. In this work, we explore the electric quadrupole driving of a quantum dot in silicon, specifically examining the cases of 5 and 13 electron occupancies.

Dimensionality and electronic correlations are crucial elements of many quantum material properties. An example is the change of the electronic structure accompanied by the loss of quasiparticles when a metal is reduced from three dimensions to a lower dimension, where the Coulomb interaction between carriers becomes poorly screened. Here, using angle-resolved photoemission spectroscopy, we report an orbital-selective decoherence of spectral density in the perovskite nickelate $\mathrm{LaNi}{\mathrm{O}}_3$ toward the monolayer limit. The spectral weight of the $d_{z2}$ band vanishes much faster than that of the $d_{x2-y2}$ band as the thickness of the $\mathrm{LaNi}{\mathrm{O}}_3$ layer is decreased to a single unit cell, indicating a stronger correlation effect for the former upon dimensional confinement. Dynamical mean-field theory calculations show an orbital-selective Mott transition largely due to the localization of $d_{z2}$ electrons along the $c$ axis in the monolayer limit. This orbital-selective correlation effect underpins many macroscopic properties of nickelates, such as metal-to-insulator transition and superconductivity, where most theories are built upon a $d_{x2-y2}\text{–}{d}_{z2}$ two-band model.

We investigate the theory of surface plasmon polaritons on a magnetic Weyl semimetal conical tip. We show that the axion term in the effective electrodynamics modifies the surface plasmon polariton dispersion relation and allows all modes with a given sign of the orbital angular momentum to be focused at the end of the tip. This is in contrast with normal metals, in which only one mode can reach the end. We discuss how this orbital angular momentum nanofocusing expands the potential of technologies that use this degree of freedom.

We study a quantum system that consists of two fermionic chains coupled by a driven quantum point contact (QPC). The QPC contains a bond with a periodically varying tunneling amplitude. Initially, the left chain is packed with fermions, while the right one is empty. We numerically track the evolution of the system and demonstrate that, at frequencies above a certain threshold, the current through the QPC halts, and the particle imbalance between the chains remains forever. This implies a spectacular breakdown of the Floquet version of the eigenstate thermalization hypothesis that predicts a homogeneous particle density profile at large times. We confirm the effect for various driving protocols and interparticle interactions.

We build Floquet-driven capacitive circuit networks to realize topological states of matter in the frequency domain. As visible through our Floquet Laplacian formalism, the intertwining of static circuit components and parametric Floquet driving effectively creates a barrier in the frequency dimension, allowing to resolve the bulk-boundary correspondence of Floquet topological matter. By implementing a Su-Schrieffer-Heeger Floquet lattice model and measuring the associated circuit Laplacian and characteristic resonances, we demonstrate Floquet topological edge modes emerging at this frequency space barrier. Floquet circuits allow for the creation of topological phenomena in synthetic frequency dimensions with just a single unit cell of time-variable circuit components.

Quasicrystals (QCs) lack three-dimensional periodicity of atomic arrangement but possess long-range structural order, which are distinct from periodic crystals and random systems. Here, we show how the ferromagnetic (FM) order arises in the icosahedral QC (i-QC) on the basis of the Monte Carlo simulation of the Heisenberg model on the Yb lattice of ${\mathrm{Cd}}_{5.7}\mathrm{Yb}$ composed of regular icosahedrons. By finite-size scaling of the Monte Carlo data, we identified the critical exponents of the magnetization, magnetic susceptibility, and spin correlation length, $\beta =0.508\left(30\right), \gamma =1.361\left(59\right)$, and $\nu =0.792\left(17\right)$, respectively. We confirmed that our data satisfy the hyperscaling relation and estimated the other critical exponents $\alpha =-0.376\left(51\right), \delta =3.68\left(23\right)$, and $\eta =0.282\left(65\right)$. These results show a universality class inherent in the i-QC, which is different from those in periodic magnets and spin glasses. In the i-QC, each Yb site at vertices of the regular icosahedrons is classified into eight classes with respect to the coordination numbers of the nearest-neighbor and next-nearest-neighbor bonds. We revealed the FM-transition mechanism by showing that the difference in the local environment of each site is governed by cooperative evolution of spin correlations upon cooling, giving rise to the critical phenomena.

The challenge of controlling the quantum states of matter via light has been at the forefront of modern research on driven quantum matter. We explore the imprinting effects of structured light on superconductors, demonstrating how the quantum numbers of light—specifically spin angular momentum, orbital angular momentum, and radial order—can be transferred to the superconducting (SC) order parameter and control vortex dynamics. Using Laguerre-Gaussian beams, we show that by tuning the quantum numbers and the amplitude of the electric field, it is possible to manipulate a variety of vortex dynamics, including breathing vortex pairs, braiding vortex pairs, vortex droplets, and swirling two-dimensional vortex rings. More complex structures of vortex clusters, such as vortex flake structures, and standing wave motions, also emerge under specific quantum numbers. These results demonstrate the ability to control SC vortex motion and phase structures through structured light, offering potential applications in quantum fluids and optical control of superconducting states. Our findings present a diagram that links light's quantum numbers to the resulting SC vortex dynamics, highlighting the capacity of light to transfer its symmetry onto superconducting condensates. We point out that this approach represents the extension of printing to quantum printing by light in a coherent state of electrons.

We propose an approach to use linearly polarized light to imprint superconducting (SC) vortices. Within the framework of the generalized time-dependent Ginzburg-Landau equations, we demonstrate the induction of the coherent vortex pairs that move in phase with electromagnetic wave oscillations. The overall vorticity of the superconductor remains zero throughout the cycle. Our results uncover rich multiscale dynamics of SC vorticity and suggest optical applications for various types of structured light. In a departure from classical laser printing, the laser printing proposed here can be viewed as quantum printing where we induce quantum excitations in the SC liquid.

We develop a systematic method for constructing asymptotic quantum many-body scar (AQMBS) states. While AQMBS states are closely related to quantum many-body scar (QMBS) states, they exhibit key differences. Unlike QMBS states, AQMBS states are not energy eigenstates of the Hamiltonian, making their construction more challenging. We demonstrate that, under appropriate conditions, AQMBS states can be obtained as low-lying gapless excited states of a parent Hamiltonian, which has a QMBS state as its ground state. Furthermore, our formalism reveals a connection between QMBS and supersymmetric (SUSY) quantum mechanics. The QMBS state can be interpreted as a SUSY-unbroken ground state.