This work presents an experimental investigation of the morphological regimes of a two-dimensional granular pile subjected to bulk discharge through a small opening in its lower center. The granular material employed is clean stainless steel spheres of diameter $d=3\mathrm{mm}$, which are poured into a transparent Hele-Shaw cell to form a triangular pile of initial height $h_0=200\mathrm{mm}$. When a small orifice of width $w$ is made in the lower center of the pile, three morphological regimes—each associated with a different type of granular outflow—are observed, depending on $w/d$: When $w\lesssim 2.9d$, the flow jams after the release of a few particles and no morphological changes in the pile are observed (jamming flow regime), while for $w\gtrsim 5d$, two disjoint granular piles emerge after a continuous discharge event (catastrophic flow regime). In the intermediate range $2.9\lesssim w/d\lesssim 5.0$, the outflow leads to a transient regime characterized by a double-tip morphology with the average height $\langle h\rangle$ following a power-law relation with ${\left(w_{\mathrm{c}}-w\right)}^{\beta }$, where $\beta \approx 1.2$ and $w_{\mathrm{c}}\approx 5.0d$ denotes the critical opening size beyond which the flow regime is catastrophic. Our experiments corroborate, in addition, the continuous flow threshold, as predicted in previous numerical simulations, and suggest a connection between the morphology of a granular pile under bulk discharge and the frictional properties of its constituent particles.

Electric dipole moments (EDMs) are sensitive probes of fundamental symmetries and central to searches for physics beyond the standard model. We present a symmetry-based, Zeeman-analog operator framework that places magnetic and electric dipole physics on parallel footing under electromagnetic duality and introduce a polar-sector pseudo-angular-momentum degree of freedom in parity space together with an associated electric Landé $g$ factor, $g_E$, that organizes induced orbital dipoles. Following Ohanian's effective-current formulation of the Zeeman effect, we construct its electric dual: The wavefunction's microscopic polarization admits an equivalent effective magnetic probability-current representation, providing a field-equivalence description of parity-mixed charge displacement. In this notation, the total EDM expectation takes the unified form $\langle {\widehat{\vec{d}}}_{\mathrm{tot}}\rangle =d_B(g_E\frac{\langle {\widehat{\vec{J}}}_p\rangle }{\hslash }+g_E^e\frac{\langle \widehat{\vec{S}}\rangle }{\hslash })$, with $g_E^e=\frac{2d_{\mathrm{int}}}{d_B}$, where ${\widehat{\vec{J}}}_p$ captures Stark-induced pseudoangular momentum and $\widehat{\vec{S}}$ encodes any intrinsic (spin-aligned) EDM $d_{\mathrm{int}}$ from symmetry-violating interactions. We define a natural electric dipole unit (the “Bohr EDM”) as $d_B\equiv e{a}_0=\frac{2{\mu }_B}{c\alpha }$ ($a_0$ the Bohr radius and ${\mu }_B$ the Bohr magneton). As a canonical analytic benchmark, we show in the hydrogenic problem that a static electric field couples within a fixed $n$ manifold through the scaled Runge-Lenz structure, yielding a compact Landé-like description and reproducing the Stark doublet (e.g., $|\langle d_{\mathrm{orb}}\rangle |=3d_B$ for the $2s\text{–}2p_{m=0}$ mixing).

This work presents a digital quantum simulation of a three-level atomic system interacting with a single-mode electromagnetic field based on the Jaynes-Cummings model, implemented on IBM Quantum superconducting processors. A qutrit is encoded using two physical qubits to represent the atomic states, while an additional qubit encodes the truncated field mode, enabling the realization of effective $\mathrm{\Lambda }$-type atomic dynamics. The continuous-time light-matter interaction is implemented in a digital form by discretizing the evolution using Suzuki-Trotter decomposition. In contrast to an analog realization, the digital simulation replaces the continuous evolution with a sequence of quantum gates whose parameters are explicitly controlled. Phase evolution arising from the interaction Hamiltonian is digitally encoded using calibrated $R_Z$ gates, whose rotation angles are fixed by the physically relevant coupling scale and the chosen Trotter time step. State preparation is achieved using Hadamard and parametrized rotation gates, while the interaction dynamics are implemented through controlled operations. A comparative analysis between first- and second-order Trotter implementations reveals a trade-off between digital accuracy and hardware-induced noise. Overall, the results demonstrate that calibrated gate operations and noise-aware circuit design enable reliable digital simulation of multilevel light-matter interactions on noisy intermediate-scale quantum platforms.

Through two-dimensional, three-velocity-component particle-in-cell simulations of freely decaying subion turbulence, intermittent localized regions with $\mathbf{E}·\mathbf{B}\ne 0$ are found, in the early electron-scale interaction phase, to be statistically associated with decreases in $|H_{V_s}|$, the fixed-gauge structure-integrated magnetic-helicity diagnostic. This structure-level behavior coincides with a decline of the Saffman helicity-variance plateau value $I_H$. Motivated by these observations, we propose a source-compensated, history-dependent helicity density that satisfies an exact local balance identity by construction, enabling Saffman-type two-point correlation integrals, which, under standard flux-decorrelation assumptions, can exhibit intermediate-scale plateaus that are roughly time independent. In the simulations, such plateaus are observed to remain approximately invariant over the measured kinetic interval even as $I_H$ evolves during the early kinetic stage. Under approximate single-scale self-similarity, the plateau behavior of the magnetic integral is consistent with the two-dimensional decay constraint $BL\sim \text{const}$. For initially net-helical configurations, we observe rapid development of mixed-signed magnetic-helicity patches and a decrease of the global fractional helicity, such that the decay over the kinetic interval is again most consistent with the cancellation-dominated scaling constraint.

Unconventional superconductivity remains one of the central unsolved problems in quantum materials, and revealing its connection to the normal state is widely believed to be key to uncovering the pairing mechanism. Previous efforts have largely focused on the temperature range immediately above the superconducting transition, where specific scattering channels—such as strange-metal transport—have been identified as sharing a possible microscopic origin with superconductivity. Here, we use machine learning to explore possible correlations between normal-state resistivity and superconductivity in Fe-based compounds. We find that resistivity data in the temperature window of 150–300 K, far above the typical critical temperature ($T_c$) of this family, can be used to classify whether a compound becomes superconducting. Owing to the limited size of the dataset, the underlying physical origin of this correlation cannot yet be determined. Nevertheless, the results suggest that high-temperature resistivity may contain useful empirical information for superconductivity prediction, motivating larger and more systematic experimental datasets.

We theoretically investigate dispersion of plasma waves propagating in a lateral plasmonic crystal based on a two-dimensional electron system with grating gates. Two specific configurations are analyzed: a system with single grating gate having ungated gaps and a double-grating-gate structure. We calculate the dispersion relations for the fundamental and several higher-order plasma modes, classifying them as either bright or dark excitations. At the boundaries of the Brillouin zones, the dispersion of both types of excitations is shown to be quadratic, justifying the introduction of effective bright and dark plasmon masses. In the low-frequency limit, the plasmonic-crystal spectrum exhibits an acoustic plasma mode characterized by a certain velocity. We demonstrate that the effective plasmon mass and acoustic velocity are highly sensitive to both crystal geometry (specifically the lattice filling factor) and the gate voltages, enabling wide-range tunability.

Solitary waves are important phenomena for particle acceleration and energy transport in both astrophysical and laboratory laser plasmas. To investigate their characteristics, we introduce a physics-informed neural network (PINN)-based method to infer the governing partial differential equation that describes solitary waves in one-dimensional particle-in-cell (PIC) simulations. Benchmark tests using numerical solutions of partial differential equations demonstrate that the PINN can successfully infer advection-diffusion, Burgers, and Korteweg–de Vries (KdV) equations with reasonable accuracy. We then apply the PINN to PIC simulation data modeling the irradiation of a femtosecond laser onto a carbon target, in which a laser-driven peak structure propagates as a solitary wave. Both the PINN-predicted data and the solution of the equation with the PINN-inferred coefficients agree well with the original simulation data. The inferred coefficients indicate that the governing equation is a nonlinear KdV-like equation and that the solitary waves are consistent with the theoretical properties of ion acoustic solitons. These results show that the solitary waves in laser-irradiated plasmas behave as KdV solitons, demonstrating that the proposed method is effective for understanding nonlinear plasma waves.

We present an implementation of an atomic magnetometer based on free spin precession of optically pumped ${}^{87}\mathrm{Rb}$ atoms. The design features a microfabricated vapor cell with an effective volume of $7.1{\mathrm{mm}}^3$ containing isotopically enriched ${}^{87}\mathrm{Rb}$ and nitrogen buffer gas. The magnetometer is designed to operate in the Earth-field range, exhibiting a magnetic noise floor of about $147\mathrm{fT}/\sqrt{\mathrm{Hz}}$ at field strengths comparable to Earth's magnetic field, i.e., around $50\mu \mathrm{T}$. This is in close agreement with the Cramér-Rao lower bound of $118\mathrm{fT}/\sqrt{\mathrm{Hz}}$. The good sensitivity as well as the high dynamic range enables a wide range of applications, including magnetocardiography and geomagnetic measurements.

Short-time approximations and path integrals may be dominated by high-energy or large-field contributions, especially for singular interactions, motivating regulators that suppress such contributions while remaining removable. We show that smooth regulators of this kind can arise as conditional maps generated by interference in coherently controlled, postselected superpositions of time evolutions. In quantum mechanics, a Gaussian superposition of short-time translations produces a Gaussian energy filter that renders time-sliced kernels well behaved for singular potentials while recovering the target unitary dynamics when the regulator is removed and in the continuum limit. We also discuss a related momentum-space regulator obtained by coherently smearing a kinetic prefactor. In scalar quantum field theory, local Gaussian smearing of the quartic coupling induces a positive local ${\varphi }^8$ term in the Euclidean action, providing a symmetry-compatible large-field stabilizer. We derive short-time error bounds, analyze multistep success probabilities, and discuss how the construction can be used as a removable regulator together with conventional ultraviolet regularization.

We studied the longitudinal and transverse magnetoresistance of helical magnets, MnSi and ${\mathrm{Mn}}_{1-x}{\mathrm{Co}}_x\mathrm{Si}$, at temperatures between 1.8 and 100 K and in magnetic fields up to 9 T. The helical and conical phases of MnSi show a negative response to low applied magnetic fields at 1.8 and 4 K, which is obviously a result of suppressing weak magnetic fluctuations. However, in the field-induced phase at low temperature, the magnetoresistance of MnSi becomes positive and anisotropic, indicating the action of the Lorentz force. All substances exhibited negative longitudinal and transverse magnetoresistance at temperatures above 4 K, which is most likely related to the suppression of spin fluctuations by the magnetic field. Note that in contrast to our finding, the longitudinal magnetoresistance of ferromagnetic metals was found to be positive. The unique positive and anisotropic magnetoresistance of pure MnSi at low temperatures (1.8 and 4 K) in the induced ferromagnetic phase shows effective suppression of fluctuations by the magnetic field. The significant difference in behavior between pure MnSi and doped MnSi lies in the specifics of the latter material, which forms a sort of helical fluctuation cloud and reveals quantum critical properties at low temperatures. The observed isotropic magnetoresistance in MnSi and ${\mathrm{Mn}}_{1-x}{\mathrm{Co}}_x\mathrm{Si}$ at higher temperatures can tentatively be attributed to the shortening of the mean free path of electrical carriers due to scattering on magnetic fluctuations and impurities, which results in a suppression of Lorentz force effects.

Topological quantum computation, featuring qubits built out of anyonic excitations known as Majorana zero modes (MZMs), have long presented an exciting route toward scalable quantum computation. Recently, the advent of altermagnetic materials has presented a pathway toward localized MZMs on the boundary of two-dimensional materials, consisting of an altermagnetic film, subject to a superconducting proximity effect from a superconducting substrate. In this work, we demonstrate the possibility for an altermagnet-superconductor heterostructure, to not only harbor MZMs, but also freely manipulate their position along the topological boundary of the material, via rotation of the Néel vector. Using this mechanism, on a square platform, we utilize a time-dependent method to simulate the Z gate via braiding, and then extend this to a larger H junction, where we implement the $\sqrt{\mathrm{X}}$ and $\sqrt{\mathrm{Z}}$ gates on a single-qubit system. Further, this structure is eminently scalable to many-qubit systems, thus providing the essential ingredients toward universal quantum computation.

OpenAI’s reasoning model o3-mini-high was used to carry out an exact analytic study of one-dimensional ferrimagnetic site- and bond-decorated $q$-state Potts models. We demonstrate that the finite-temperature ultranarrow phase crossover (UNPC), driven by a hidden “half-ice, half-fire” state recently discovered in the $q=2$ case (Ising model), persists for $q>2$. Moreover, we identify unique features for $q>2$, including the dome structure in the field-temperature phase diagram, and for large $q$ a secondary high-temperature UNPC to the fully disordered paramagnetic state. As the UNPC quickly approaches a genuine transition by enhancing $J$, the interaction between the backbone spins, two distinct behaviors emerge: In the site-decorated Potts model, $T_0$ is independent of $J$ and thus remains unchanged (Type-I UNPC), and in the bond-decorated Potts model with $q>2$, $T_0$ depends on $J$ and quickly shifts toward a finite temperature as $J$ increases (Type-II UNPC). These results establish a versatile framework for engineering controlled fast state-flipping switches in low-dimensional systems. Our nine-dan artificial intelligence (AI)-contribution framework assigns AI the meritorious status of AI-co-led discovery in this work.

We explicitly show that the quantum teleportation protocol can be employed to completely reconstruct arbitrary two- and three-qubit density matrices. We also extend the present analysis to $n$-qubit density matrices. The only quantum resources needed to implement the teleportation-based quantum state tomography protocol are the ability to make Bell measurements and the ability to prepare a few different single-qubit states to be teleported from Alice to Bob.

Optical tomograms can be envisaged as patterns. The Wasserstein generative adversarial network (WGAN) algorithm provides a platform to train the machine to compare patterns corresponding to input and generated tomograms. Using a deep-learning framework with two convolutional neural networks and WGAN, we have trained the machine to generate tomograms of Fock states, coherent states (CSs), and the single-photon added CS (1-PACS). The training process was continued until the Wasserstein distance between the input and output tomographic patterns levelled off at a low value. The mean photon number, variances, and higher moments were extracted directly from the generated tomograms, to distinguish between different Fock states and also between the CS and the 1-PACS, without using an additional classifier neural network. The robustness of our results has been verified using two error models and also with different colormaps that define the tomographic patterns. We have examined whether the training program successfully reflected some of the findings in a recent experiment in which state reconstruction was carried out to establish that the fidelities between an amplified CS, an optimal CS, and a 1-PACS were close to unity, over a range of parameter values. By training the machine to reproduce tomograms corresponding to these specific states, and comparing the mean photon numbers of these states obtained directly from the tomograms, we have established that the variations in these observables reflect the experimental trends. State reconstruction from tomograms could be challenging, in general, since the Hilbert space associated with quantized light is large. The tomographic approach provides a viable alternative to detailed state reconstruction. Our work demonstrates the use of machine learning to generate optical tomograms from which the states can be directly characterized.

We present a general formalism for performing a time-dependent Bogoliubov analysis of a dynamically unstable Bose-Einstein condensate, which extends the quasiparticle projection method of Morgan et al. [Phys. Rev. A 57, 3818 (1998)] to cases with a complex spectrum. By introducing the proper left eigenvectors associated with each regime, we construct a biorthogonal basis. While the usual Bogoliubov normalization $\langle u|u\rangle -\langle v|v\rangle =1$ may not hold in this basis, it still allows for a complete mode decomposition and an accurate reconstruction of arbitrary perturbations over time. This approach extends the applicability of the Bogoliubov framework beyond the stable regime, providing a consistent analysis of the time evolution of unstable condensates. As a proof of concept, we apply the method to a one-dimensional condensate with attractive interactions, which is dynamically unstable and evolves into nonstationary localized structures seeded by small perturbations. Overall, the present method provides a complete and robust mode expansion that remains meaningful beyond the linear regime and useful for characterizing the macroscopic development of instabilities.

Entangled free electrons constitute a key missing resource for quantum electron optics, with direct relevance to nonclassical electron probes, collective radiation, and quantum-enhanced electron-matter spectroscopy. We propose a heralded protocol for generating Bell pairs of spatially separated free electrons by transferring entanglement from an atomic two-level-system (TLS) pair to electronic energy-sideband degrees of freedom. Local resonant electron-TLS exchange converts a delocalized atomic excitation into a delocalized electronic sideband excitation, and a projective TLS measurement certifies successful Bell-pair generation. A self-contained input-output theory establishes the conditional transfer map, the heralding probability, and the relation between the initial atomic resource and the heralded electronic entanglement. Full-Hamiltonian simulations confirm the robustness of the protocol against detuning, pulse shaping, and counterrotating corrections, with the dominant beyond-rotating-wave approximation effects identified as a Bloch-Siegert-type shift and weak leakage outside the target manifold. The results establish a quantitative route to certifiable entangled free electrons and provide a foundation for integrating stationary quantum resources into nonclassical quantum electron optics.

The halide double perovskite ${\mathrm{Cs}}_2{\mathrm{AgBiBr}}_6$ has been proposed as a potential replacement for organic halide perovskites for photovoltaic applications. Further investigation of its dielectric response, optical properties, and structural stability is thus warranted. ${\mathrm{Cs}}_2{\mathrm{AgBiBr}}_6$ exhibits a well-documented structural phase transition at 120 K but indications for an additional lower-temperature ($\sim 40$ K) phase transition have also been reported. On the basis of measurements of the specific heat capacity, temperature-dependent powder x-ray diffraction, low-frequency capacitance, and infrared reflectivity, we clarify the previously reported splitting of phonon modes in the Raman spectrum at $\sim 40\mathrm{K}$ as due to a subtle structural phase transition from the tetragonal $I4$/$m$ structure to a monoclinic $P{12}_1$/$n1$ crystal structure. The infrared-active vibrational modes are experimentally investigated in the three structural regimes. In the cubic structure at room temperature, the four infrared-active modes are observed at 135, $\sim 85$, 55, and $\sim 25{\mathrm{cm}}^{-1}$. As the symmetry reduces to tetragonal, a minute splitting of these modes is found; however, below 40 K additional mode splitting is observed, indicating a further reduction in symmetry.

A realistic model of a projective quantum measurement is presented that provides a physical justification for the collapse postulate without invoking the macroscopic nature of a detector. The analysis adopts a minimally realist interpretation of the formalism, in which objective reality is ascribed only to quantum states associated with definite, empirically accessible physical properties. It is shown that objective state reduction arises from an irreversible microscopic process, enforced by appropriate boundary conditions, while the subsequent amplification stage merely reveals, at the macroscopic scale, the randomly selected measurement outcome.