The advection-diffusion equation is simulated via several quantum algorithms. Three formulations are considered: (1) Trotterization, (2) variational quantum time evolution (VarQTE), and (3) adaptive variational quantum dynamics simulation (AVQDS). These schemes were originally developed for the Hamiltonian simulation of many-body quantum systems. The finite-difference discretized operator of the transport equation is formulated as a Hamiltonian and solved without the need for ancillary qubits. Computations are conducted on a quantum simulator (IBM Qiskit Aer) and a superconducting quantum hardware (IBM Fez). The former emulates the latter without the noise. The actual hardware implementation experiences significant noise. The results of the quantum simulator are compared with data from direct numerical simulation (DNS) with infidelities of the order ${10}^{-5}$. In the quantum simulator, Trotterization is observed to have the lowest infidelity and is suitable for fault-tolerant computation. The AVQDS algorithm requires the lowest gate count and circuit depth. The VarQTE algorithm is the next best in terms of gate counts, but the number of its optimization variables is directly proportional to the number of qubits. Due to current hardware limitations, Trotterization cannot be implemented, as it has an overwhelmingly large number of operations. Meanwhile, AVQDS and VarQTE can be executed at the hardware level. These algorithms present a new paradigm for computational transport phenomena on quantum computers.

We present an experimental approach to the formation of sub-100 ps ion pulses at $4.5-8.5$ keV energies using laser-stimulated desorption from a tungsten nanotip at room temperature. The illumination of the tip apex with femtosecond ultraviolet laser pulses results in the ionization of adsorbed atomic and molecular species through the enhancement of a localized electric field. Unlike photoionization of atoms and molecules in the gas phase in extended volumes, determined by a typical laser focal volume, our approach naturally exploits a nanometric ionization region from tungsten nanotips with tip radii of $15-150\mathrm{nm}$ and operates at a moderate optical fluence of ${10}^{11}\mathrm{W}/{\mathrm{cm}}^2$. Time-of-flight measurements demonstrate stable and well-timed ion pulses. A systematic exploration of the ion pulse characteristics on laser parameters and loading gas pressures has been conducted. Our compact, yet simple, source design renders time-resolved ion-solid interaction studies practically possible, paving the way for future pump-probe studies.

We propose a pseudoratchet mechanism based on one-dimensional (1D) quantum Brownian motion, offering a route to energy-efficient Brownian computing without relying on conventional ratchet structures. Quantum resonance effects in 1D system naturally partition the momentum space into dynamically independent subspaces, each of which lacks inversion symmetry. This leads to spontaneous unidirectional particle transport near thermal equilibrium, without external forces or asymmetric potential gradients. We analyze this pseudoratchet mechanism from kinetic and entropic perspectives and show that the directional transport is sustained without energy dissipation, remaining fully consistent with the second law of thermodynamics. Our analysis provides a microscopic and physically grounded foundation for reversible information transport in Brownian computing.

We introduce an x-ray imaging technique to facilitate dose-efficient propagation-based phase contrast imaging (PB-PCI) of large, centimeter-sized samples. The dose efficiency is realized by generating image contrast for low sampling frequencies, i.e., large pixel sizes, which would require propagation distances of tens to hundreds of meters in conventional PB-PCI. By magnifying the spatial frequency distribution of the diffracted wave field behind the sample, we strongly enhance the image contrast at short physical propagation distances, corresponding to kilometer-long distances. For this purpose, the wave field is demagnified by asymmetric Bragg crystal optics. Concomitantly, the crystal arrangement substantially reduces image blur caused by the finite x-ray source size. We demonstrate experimentally the significant increase in image contrast compared to conventional PB-PCI at the same short physical propagation distance. In combination with a subsequent Bragg magnifier, the method will allow for an even higher dose efficiency, rendering this technique a potential candidate for, e.g., low-dose (bio)medical diagnostics.

Understanding entanglement remains one of the most intriguing problems in physics. While particle and site entanglement have been studied extensively, the investigation of length- or energy-scale entanglement—quantifying the information exchange between different length scales—has received far less attention. Here, we identify the quantics tensor train (QTT) technique, a matrix product state-inspired approach for overcoming computational bottlenecks in resource-intensive numerical calculations, as a renormalization group method by analytically expressing an exact cyclic reduction-based real-space renormalization scheme in QTT language, which serves as a natural formalism for the method. In doing so, we precisely match the QTT bond dimension—a measure of length-scale entanglement—to the number of rescaled couplings generated in each coarse-graining renormalization step. While QTTs have so far been applied almost exclusively to numerical problems in physics, our analytical calculations demonstrate that they are also powerful tools for mitigating computational costs in semianalytical treatments. We present our results for the one-dimensional tight-binding model with $n\mathrm{th}$-nearest-neighbor hopping, where the $2n$ rescaled couplings generated in the renormalization procedure precisely match the QTT bond dimension of the one-particle Green's function.

We experimentally investigate the frosting phenomena beneath freezing droplets on cryogenic surfaces and reveal the emergence of previously unreported dual frost halo rings. We report that droplets impacting from low heights produce dual frost halo rings beneath the freezing droplet, whereas higher impact heights result in a single halo ring. The formation of dual halos originates from the raised bimodal morphology of the freezing droplet, which is shaped by the interplay of hydrodynamic spreading, freezing kinetics, and mechanical peeling dynamics. The locally thicker region of the raised thickness profile cools more slowly than the surrounding edge, maintaining a higher temperature that promotes localized sublimation at the freezing droplet base and subsequent vapor desublimation onto the adjacent cryogenic substrate, thereby resulting in an internal frost halo ring. Through capillary wave propagation analysis, we identify the morphology transition of different frost halo rings characterized by a power-exponent relationship between the dimensionless droplet falling height and radius. These findings provide insights into the complex interplay between capillary hydrodynamics and freezing kinetics under cryogenic conditions.

We provide a complete classification of the integrability and nonintegrability of the spin-1 bilinear-biquadratic model with a uniaxial anisotropic field, which includes the Heisenberg model and the Affleck-Kennedy-Lieb-Tasaki model. It is rigorously shown that, within this class, the only integrable systems are those that have been solved by the Bethe ansatz method, and that all other systems are nonintegrable, in the sense that they do not have nontrivial local conserved quantities. Here, “nontrivial” excludes quantities like the Hamiltonian or the total magnetization, and “local” refers to sums of operators that act only on sites within a finite distance. This result establishes the nonintegrability of the Affleck-Kennedy-Lieb-Tasaki model and, consequently, demonstrates that the quantum many-body scars observed in this model emerge independently of any conservation laws of local quantities. Furthermore, we extend the proof of nonintegrability to more general spin-1 models that encompass anisotropic extensions of the bilinear-biquadratic Hamiltonian and completely classified the integrability of generic Hamiltonians that possess translational symmetry, $\mathrm{U}\left(1\right)$ symmetry, time-reversal symmetry, and spin-flip symmetry. Our result has accomplished a breakthrough in nonintegrability proofs by expanding their scope to spin-1 systems.

A quantum system that interacts with an environment generally undergoes nonunitary evolution described by a non-Markovian or Markovian master equation. In this paper, we construct the non-Markovian Redfield master equation for a quantum scalar field that interacts with a second field through a bilinear or nonlinear interaction on a Minkowski background. We use the resulting master equation to set up coupled differential equations that can be solved to obtain the equal-time two-point function of the system field. We show how the equations simplify under various approximations including the Markovian limit and argue that the Redfield equation-based solution provides a perturbative resummation to the standard second-order Dyson series result. For the bilinear interaction, we explicitly show that the Redfield solution is closer to the exact solution compared to the perturbation theory-based one. Further, the environment correlation function is oscillatory and nondecaying in this case, making the Markovian master equation a poor approximation. For the nonlinear interaction, on the other hand, the environment correlation function is sharply peaked and the Redfield solution matches that obtained using a Markovian master equation in the late-time limit.

This work addresses droplet condensation on surfaces spanning hydrophobic to hydrophilic wettabilities. A stochastic mesoscale model based on the theory of fluctuating hydrodynamics and the thermodynamics of a diffuse interface approach shows how direct simulation of the vapor-liquid transition from the nucleation process to droplet hydrodynamics can be achieved. Such simulations explain the role of wettability in filmwise and dropwise condensation regimes and the main limitations of classical nucleation theory.

We investigate optimal work protocols for a tracer particle with odd mobility, confined in a rotationally asymmetric parabolic potential, and driven by temporally correlated (active) noise originating from an active process. Two control strategies are considered: open loop (without measurement of the initial active force) and closed loop (with measurement-based feedback). In the open-loop case, neither activity nor odd mobility affects the average optimal work; however, the potential asymmetry enables the work extraction, and the oddness parameter $\kappa$ shapes the protocol structure—introducing asymmetries and even backward jumps at the initial and final times. In the closed-loop setting, both activity and odd mobility shape the protocol design to enable work extraction. Optimal protocols exhibit directional asymmetries, including discontinuities and reversals, which depend on the alignment of the initial active force and the persistence time. Maximum work extraction occurs when the initial force aligns with the target at an intermediate persistence time, even in symmetric potentials. Furthermore, in regimes where such alignment disfavors work extraction for a normal tracer, odd mobility facilitates it. These findings highlight the potential for energy harvesting in active systems, driven by feedback and asymmetric interactions between different degrees of freedom.

The dynamics of polar order have received much attention in the literature on collective motion. However, milling dynamics, where organisms exhibit rotational motion around the group center, is understudied. Here, we investigate the stochastic dynamics of milling swarms of whirligig beetles [Dineutus discolor (Coleoptera: Gyrinidae)] in small to medium groups (50 to 200) where noise arising due to the finite sizes of the swarms cannot be ignored. We quantify the milling order parameter of beetle swarms and show that they exhibit a “transition” from a disordered state to a milling state as a function of group size. We employ a method of data-driven discovery of dynamical equations to obtain stochastic differential equations (SDEs) that disentangle deterministic and stochastic factors driving the milling dynamics. Crucially, we find that the milling order at large group sizes can be explained largely by the deterministic terms of the SDE, while intrinsic stochasticity switches the system between clockwise and counterclockwise milling states. Furthermore, we find that an agent-based model in which each agent aligns with the average direction of its local neighbors and attracts toward neighbors on a larger spatial scale produces stochastic dynamics of milling (and corresponding SDEs) that are consistent with the data-derived SDEs. However, contrary to expectations from mean field theory, both data and explicit agent-based models show that the dynamical equations can change their qualitative features with the group size even when individual interaction rules do not change. In summary, we show evidence for the milling order transition and characterize the role of intrinsic stochastic dynamics in swarming beetles.

While bipartite quantum correlations have been extensively studied across various fields, the role of multipartite quantum correlations in many-body systems remains elusive due to their complex structure. A primary challenge lies in the fact that the calculation of multipartite quantum correlation measure often requires an exponential cost with respect to the system size. In this work, we address this problem by adopting a thermodynamic approach: We introduce a measure of multipartite quantum correlations based on the difference in extractable thermodynamic work between global operations and LOCC (local operations and classical communication). This can be regarded as a multipartite generalization of the bipartite work deficit, which has attracted attention as a thermodynamic measure of bipartite quantum correlation. Importantly, we develop an efficient method for computing the multipartite work deficit in a special class of quantum many-body systems described by matrix product states (MPS). The numerical cost of this method scales linearly with system size, significantly reducing the exponential overhead required for direct calculations. We apply this method to an MPS family and show that a quantum phase transition is well captured by the multipartite work deficit, which exhibits singular behavior at the transition point. Our work shows that the multipartite work deficit not only highlights the fundamental connection between multipartite quantum correlations and quantum thermodynamics, but also serves as an efficiently computable probe of the structures of quantum many-body systems.

We explore the interplay among entanglement suppression, quantum statistics, and enhanced symmetries in the nonrelativistic $S$-wave scattering involving the lowest-lying spin-3/2 baryons, which can be considered as four-dimensional qudits. These baryons form a ten-dimensional representation (decuplet) under the SU(3) light-flavor symmetry and, in this limit, are considered indistinguishable under strong interactions. Treating the $S$ matrix in the spin-3/2 baryon-baryon scattering as a quantum logic gate in the spin space, we study the consequence of entanglement suppression and compute the entanglement power of the $S$ matrix. When the entanglement power vanishes, the $S$ matrix is either an Identity or a SWAP gate and spin-flavor symmetries and/or nonrelativistic conformal invariance emerge, as previously observed in spin-1/2 baryons. In the case of scattering identical particles, the entanglement power never vanishes due to constraints from spin statistics, which we interpret as projection-valued measurements onto symmetric or antisymmetric Hilbert space and define the entanglement power accordingly. When the entanglement power is nonvanishing but sits at a global or local minimum, enhanced symmetries still emerge and the $S$ matrix can be interpreted as an Identity or a SWAP gate acting on the restricted Hilbert space allowed by quantum statistics. In general, when scattering identical spin-$s$ particles, we identify an enhanced $\mathrm{SU}{(2s+1)}_{\mathrm{spin}}$ symmetry for the Identity gate.

Controlling emergent structural order in spatially constrained systems is a fundamental challenge. Using large-scale simulations of a model fluid at equilibrium conditions, we show that geometric confinement alone can stabilize fluid and hyperuniform labyrinthine phases. Moreover, confinement can induce self-assembly into distinct regimes—ranging from nonhyperuniform to antihyperuniform configurations—providing a robust mechanism for tuning spatial order. Our results identify confinement as a minimal design principle for engineering systems with target structural properties, including (anti)hyperuniformity, without relying on genetic or chemical specificity, and with broad applications in multiple disciplines and technologies.

We develop an exact computational method based on numerical $X$ propagators for solving polaron models with arbitrary nonlinear couplings of local vibration modes to the electron density and magnitude of the hopping amplitude. Our approach covers various polaron models, some of which were impossible to treat by any existing approximation-free techniques. Moreover, it remains efficient in the most relevant but computationally challenging regime of phonon frequencies much smaller than the electron bandwidth. As a case study, we consider the double-well type nonlinear model with quadratic ($g_2<0$) and quartic ($g_4>0$) interactions describing a broad class of technologically important materials, such as quantum paraelectric compounds and halide perovskites. We observe, depending on the model parameters, three qualitatively different regimes: (1) quantum interplay of quartic and quadratic interactions that suppresses effects of the quadratic coupling, (2) intermediate-coupling regime with exponential $\propto exp\left(\alpha g_2{\mathrm{\Omega }}^{-1/4}\right)$ scaling of the quasiparticle weight and mass renormalization, and (3) strong-coupling asymptotic behavior.

Optical crosstalk between waveguides limits the miniaturization of photonic integrated circuits. Recently, it has been shown that, using higher-order modes, the crosstalk can be significantly reduced not only between neighboring waveguides, but also between other photonic components, such as waveguide couplers and interferometers. This opens the possibility of further miniaturization of photonic chips. Here, we present a theoretical approach to investigate the peculiar properties of these low-crosstalk modes. The approach includes a semianalytical method for computing the long-range coupling coefficients of the modes. It allows us to study the dependence of light propagation on these coefficients in both finite and infinite waveguide arrays. Our findings shed light on the crosstalk suppression mechanism and intriguing discrete diffraction phenomena realizable in waveguide arrays using higher-order modes.