This study presents a mathematical model of the spatial and rotational motion of a nanodiamond in an inverted harmonic potential to create a macroscopic quantum spatial superposition. The model is based on the Stern-Gerlach interferometer scheme, which utilizes linear and quadratic magnetic fields to generate a harmonic potential (linear magnetic field) and a nonlinear potential (nonlinear/quadratic magnetic field). By incorporating two-dimensional dynamics into the model, we provide a more realistic and accurate depiction of nanoparticle dynamics in linear and inverted harmonic potentials and explore the interaction between motion in a two-dimensional plane. Importantly, we derive the equations of motion for the rotational degrees of freedom, i.e., libration, precession, and rotation. The results show that adding a magnetic-field bias term to the magnetic-field profile in the linear stage affects the classical equations of motion but does not affect the width of the wave packet. Moreover, the libration mode always forms a harmonic potential at each stage because the applied initial angular velocity is dominated by the nanoparticle's defect axis, making it more stable in the presence of the trap frequency in the orthogonal direction along the axis that enables the creation of a macroscopic quantum superposition.

We study a harmonic oscillator weakly coupled to a thermal bath and evolving under the standard quantum-optical master equation. For zero-mean Gaussian states, entropy alone does not determine the internal energy because the latter also depends on nonequilibrium Gaussian structure. We show, however, that thermal relaxation yields the exact representation $E=E(S,\dot{S})$ for every mixed Gaussian state evolving under this thermal quantum-optical master equation. Explicitly, $E(S,\dot{S})=\frac{\omega \nu \left(S\right)}{{\nu }_{\mathrm{th}}}[\nu \left(S\right)+\frac{\dot{S}}{\gamma S^{\prime }\left(\nu \left(S\right)\right)}].$ Once the thermal Gorini–Kossakowski–Lindblad–Sudarshan equation is assumed, no further expansion in the damping rate, entropy rate, or distance from equilibrium is made. The entropy rate is not an alternative instantaneous state coordinate: It depends on the open-system dynamics and therefore carries information about the coupling to the bath. This is exposed by the isolated limit, where $\dot{S}=0$ for all Gaussian states and the representation no longer determines the energy. The result thus identifies an exact thermalization-induced dynamical energetic relation, distinct from rate dependence generated by an external driving protocol. We also describe an operational test based on time-resolved purity and energy measurements. At fixed frequency, the bath only relaxes preexisting squeezing. We therefore also consider frequency modulation, which can drive an initially thermal state away from the instantaneous Gibbs family by generating off-Gibbs Gaussian structure. Within a local Gaussian continuation, the bath then relaxes this driven deformation, providing a dynamical realization of the entropy-rate dependence.

The dynamical response of amorphous solids is expected to be inhomogeneous due to the absence of translational symmetry, unlike in crystals. In this work, we use Green's function method combined with the Hessian matrix from simulation data to characterize the vibrational inhomogeneity of a two-dimensional amorphous solid. We define an order parameter for vibrational inhomogeneity, the frequency-resolved participation ratio, which equals a constant value of 1 over all frequencies for a crystal, while being around $\sim 0.7$ for almost the entire frequency range in an amorphous solid, thus indicating a similar level of vibrational inhomogeneity across most of the frequency range. The spatial distribution of vibrational inhomogeneity in the amorphous solid is presented in three ways: by frequency, at the particle level, and via percolation analysis, all showing that the vibrational inhomogeneity is fragmented and occurs at the particle scale. The results suggest that the Green's function method is a convenient tool for probing vibrational inhomogeneity and provide an alternative perspective on the role of vibrational inhomogeneity in amorphous solids.

Simulating chemical reactions on quantum computers has the potential to offer insight that cannot be gained practically from conventional quantum-chemical approaches on classical computers. This is because quantum computing provides a platform for efficient, high-level electronic structure calculations that approach the full configuration interaction (FCI) limit. Herein, we apply the cascaded variational quantum eigensolver (CVQE) algorithm to simulate the unimolecular dissociation of fluoromethane (${\mathrm{CH}}_3\mathrm{F}$) by two pathways: (1) ${\mathrm{CH}}_3\mathrm{F}\to {\mathrm{CH}}_2+\mathrm{HF}$ and (2) ${\mathrm{CH}}_3\mathrm{F}\to \mathrm{CHF}+{\mathrm{H}}_2$. We compare the results of CVQE calculations performed on the ibm_torino quantum computer to configuration interaction benchmarks run on a classical computer. Our results demonstrate that CVQE predicts lower energies than classical configuration interaction with singles, doubles, and triples for all geometries considered, and achieves chemical accuracy relative to FCI in nearly all cases. This suggests that quantum computing with CVQE can provide high-level electronic structure information for chemical reactions and other cases that require the simulation of multiple geometries.

We treat the mechanics of point particles as a one-dimensional general-relativistic gauge field theory, which may be referred to as mechanical field theory (MFT), exploiting the bundle geometry of mechanical field space (MFS). The diffeomorphism covariance of MFT encodes its relational character, arising—as in all general-relativistic physics—via the conjunction of a hole and a point-coincidence argument. Any putative “boundary problem,” meaning the claim that “spacetime” boundaries break diffeomorphism and gauge symmetries, thereby dissolves. It is highlighted that the standard path integral (PI) on the MFS, the exact analog of the PI used in gauge field theory, is conceptually and technically distinct from the standard PI of quantum mechanics. We then use the dressing field method to give a manifestly invariant and relational reformulation of MFT, which reproduces the standard textbook formulation when a clock field is chosen as a (natural) dressing field. The dressed, or basic, PI on the MFS, defining relational quantization—i.e., the quantization of invariant relational degree of freedom—is shown to reproduce the standard PI of quantum mechanics. This establishes the soundness of relational quantization as a general guiding principle: We outline it for general-relativistic gauge field theories.

The square lattice Ising model under the Brascamp-Kunz boundary conditions is a well-known exactly solvable lattice model. The exact solution of this system has been derived within the framework of Pfaffian-type method. In this paper, we provide a derivation for the solution by the Schultz-Mattis-Lieb method in the transfer matrix formalism. We set special interactions on the boundaries and take certain limit of these interactions, so that the system under the Brascamp-Kunz boundary conditions is transformed into another system under the toroidal boundary conditions. The Schultz-Mattis-Lieb method is applied to the mapping system and the partition function is exactly solved in the fermionic representation. The Fisher zeros are analytically calculated and the physical critical point is identified. We also discuss the difference between the transfer matrix approaches to the Brascamp-Kunz and to the toroidal boundary conditions. Our work introduces a member to the family of transfer-matrix-based studies for Ising model under various boundary conditions.

Evaporating a droplet containing dispersed colloids leaves behind a dried deposit whose shape is determined by capillary flows and the resulting particle transport. The classical coffee-ring effect occurs when an outward radial flow drives particles toward the droplet’s contact line as the droplet evaporates, resulting in uneven deposition. This deposition is often studied in dilute concentration regimes where, hydrodynamically, the effects of particle shape are unimportant. As particle concentration increases, it is expected that particle anisotropy should play a larger role in modifying transport and potentially suppressing coffee-ring formation. We present experiments isolating the effects of particle shape, concentration, and density, as well as solvent temperature, on the geometry of the ring deposit. By analyzing the deposits using surface profilometry to more accurately characterize ring widths, these experiments show that coffee-ring formation is independent of particle anisotropy and is instead controlled by the ratio of the particle sedimentation velocity to the velocity of the droplet’s evaporating air-water interface. Hydrodynamic simulations support this finding by providing quantitative estimates for bulk sedimentation velocity. Together, these results offer a unified picture of how multiple physical parameters determine coffee-ring geometry with direct implications for suppressing uneven deposition in practical applications.

Traversable wormhole teleportation in the Sachdev-Ye-Kitaev (SYK) model links quantum channel integrity directly to black hole interior dynamics: The teleportation fidelity is a boundary-accessible probe of the many-body scrambling that underlies the holographic wormhole. We subject the SYK boundary to a gravitational-wave (GW)-inspired periodic Floquet deformation, constructed from the lowest-dimension bilinear sector of the ${\mathrm{SYK}}_4$ interaction and motivated by the Jackiw-Teitelboim-gravity holographic dictionary, and characterize the channel response via exact numerical time evolution with disorder averaging at $\beta J=2$. The drive produces a coherent, frequency-selective fidelity suppression, validated by reoptimization under drive to separate genuine effects from calibration mismatch with four main results: (1) two distinct amplitude regimes separated near $\varepsilon \sim J$, a perturbative sensing regime and a nonperturbative strong-drive regime; (2) the channel acts as a natural low-pass filter, most sensitive at $\omega \lesssim {\beta }^{-1}$ with monotone recovery above the thermal scale; (3) an inspiral chirp drive displaces the fidelity peak to later readout times (by $\mathrm{\Delta }{t}_{\mathrm{scr}}^{\left(\mathrm{fid}\right)}=+0.11J^{-1}$, a subgrid displacement), and an out-of-time-order correlator (OTOC) diagnostic under a monochromatic drive independently resolves a scrambling delay of the same sign ($\mathrm{\Delta }{t}_{\mathrm{scr}}^{\left(\mathrm{OTOC}\right)}=+0.20J^{-1}$ at $\varepsilon =0.20J, +0.85J^{-1}$ at $\varepsilon =0.50J$), with the delay growing monotonically with drive amplitude; (4) the drive-induced fidelity suppression is nonzero and shows no systematic decrease across $N\in \{10,12,14,16\}$ Majorana modes, and is resolved above the disorder noise at three of the four system sizes. These results establish that holographic teleportation channels degrade gracefully and can be diagnosed via GW-inspired metriclike boundary deformations, with direct implications for near-term quantum-processor implementations of traversable wormhole protocols.

We investigate the detectability of gravitational wave modes (emitted by black holes and neutron stars) by third-generation, ground-based gravitational wave detectors planned to be operational in the next decade. Our analysis focuses on the Cosmic Explorer and Einstein Telescope projects, which are expected to have arm lengths of tens of kilometers and to experience the amplification of a gravitational wave signal at their free spectral range frequencies. We find that both projects will also observe with good signal-to-noise ratio the elusive w-modes, which are expected to be emitted at these frequencies by spinning neutron stars.

In loop quantum cosmology (LQC), the initial singularity is replaced by a quantum bounce, leading to a universal postbounce evolution characterized by three distinct epochs: bouncing, transition, and slow-roll inflation, before the hot big-bang universe starts. While the generic nature of inflation in the presence of an inflaton field in LQC is well established, the subsequent reheating phase—the process that thermalizes the universe and marks the beginning of the hot big bang—has remained unexplored in this quantum gravitational framework. This paper presents the first comprehensive integration of the (generalized) reheating mechanism into the LQC paradigm. Using the power law plateau potential and comparing predictions with the latest Planck 2018 and ACT 2025 data, we demonstrate that the inclusion of a reheating phase with a generic equation of state is fully consistent with the cosmological constraints. In addition, using the observational data for the amplitude and spectral index of the scalar perturbations and the tensor-to-scalar ratio, we also constrain the total number of e-folds from the bounce to the present day and find a lower bound, which is less constrained than that obtained previously from the fitting of the high-$l$ cosmic microwave background temperature power spectrum (TT), the polarization data (TT, TE, EE), and the low-$l$ polarization data (lowP). We also show that at the horizon crossing, there exist six independent algebraic equations, which uniquely determine six physical parameters, once the amplitude and the power spectral index of the pivot mode of the scalar perturbations are provided. Three of the six parameters form a complete set of the initial conditions at the horizon crossing and uniquely determine the entire evolution of the universe, including both the pre- and postbounce phases, through the modified Friedmann and Klein-Gordon equations of LQC. This is sharply in contrast to the case without considering the reheating phase.

Energy transfer and light emission behavior at subwavelength scales are governed by near-field interactions between an emitter and its surrounding refractive-index environment, which can modify emission at the nanoscale and influence the far-field response in devices such as solar cells and light-emitting diodes (LEDs). Here, we analyze light emission in a spherical structure using a classical point dipole model with emphasis on how near-field interactions affect the spontaneous emission rate, as quantified by the Purcell factor. The system is studied under two refractive-index configurations: (1) an abrupt transition from an inner sphere to the surrounding medium and (2) a gradual transition with a graded refractive index, considered for both nonabsorbing and absorbing surrounding media. Our findings show that, within the fixed-amplitude dipole considered here, even a strong increase in near-field absorption does not lead to a comparable reduction in the far-field emission. In this model, the source supplies the additional power required to compensate for such near-field losses. This distinction between near-field enhancement and radiated power to the far field is important, for example, in studies of photon recycling in semiconductors and other optoelectronic devices, where both near-field absorption and radiative emission are present. An abrupt transition in the refractive index produces repeated peaks in the Purcell factor as a function of the inner sphere radius, whereas a graded refractive index smooths these peaks. In a graded system, with increasing grading thickness, the Purcell factor converges to the refractive index of the inner sphere when the grading thickness reaches the order of the wavelength. This behavior indicates that, even when the inner sphere has a higher refractive index than the surrounding medium, the emission is not limited by the surrounding refractive index. Thus, a graded refractive-index profile provides a viable strategy for mitigating reflection losses in emission. These insights are valuable for designing photon out-coupling and photon-recycling schemes and offer a pathway for improving the performance of optoelectronic devices, including solar cells and LEDs.

The $(1+1)$-dimensional ${\mathbb{Z}}_2$ gauge theory is the simplest model that allows for quantum simulation to probe the fundamental aspects of a gauge theory coupled with dynamical fermions. To reliably benchmark such a system, it is crucial to understand the nonunitary quantum dynamics arising from effective non-Hermitian evolution and postselected monitoring protocols. This work focuses on the postselected non-Hermitian filtering dynamics of a ${\mathbb{Z}}_2$ gauge theory, where the non-Hermitian terms are associated with local and nonlocal gauge-invariant operators naturally present in the theory. We interpret the resulting dynamics as postselected filtering, where different operator sectors are coupled to loss channels with different rates. This gives a unified framework for both the local electric flux and particle-number terms and the nonlocal mesonic hopping term. Tensor network calculations are performed to probe the effect of the filtering for larger lattice sizes (up to 256-site systems). Using matrix product state calculations, the dynamics of entanglement entropy are studied as a function of the filtering rate and the coupling constant. We find that, under both local and nonlocal filtering, the late-time saturation value of the bipartite entanglement entropy remains independent of system size, providing no evidence of a measurement-induced phase transitionlike phenomenon in the postselected dynamics across the range of filtering strengths, evolution times, and system sizes considered here.

Molecular dynamics simulations of two-dimensional (2D) diplon crystals (electrons on helium films) reveal a melting crossover from first order to continuous as film thickness $d$ grows relative to lattice constant $a$. At small $d/a$, hysteresis persists at $N=40000$ alongside a strong Binder-cumulant anomaly. At large $d/a$, hysteresis vanishes and orientational correlations decay algebraically with ${\eta }_6=0.31\pm 0.04$, near the Kosterlitz-Thouless-Halperin-Nelson-Young bound of 1/4, consistent with continuous melting within the investigated system sizes and numerical resolution; disclination unbinding limits any hexatic phase to $\mathrm{\Delta }T/T_{\mathrm{m}}<0.5\%$. The diplon system thus tunes 2D melting, relevant to electrons-on-helium quantum computing.

Diffusion-based large language models have recently attracted significant interest as a promising class of nonautoregressive generative models. However, their applications to quantum many-body systems remain largely unexplored. We introduce M-Diffushadow, a multimodal diffusion language model for quantum many-body systems. In M-Diffushadow, we adopt a full attention mechanism alongside iterative decoding, which better aligns with the physical characteristics of quantum systems and thereby enables a more faithful modeling of such systems. As a multimodal approach, M-Diffushadow enables bidirectional cross-modal inference, reconstruction from partially observed multimodal records, and fully joint generation without prior measurement outcomes, aligning naturally with realistic experimental constraints where measurement access is limited or incomplete. We demonstrate the effectiveness of the framework on the one-dimensional transverse-field Ising model (TFIM), where generated data accurately reproduce ground-state energies and correlation functions across different phases. We further provide an additional numerical example on the XXZ spin chain to support the applicability of M-Diffushadow beyond the original TFIM benchmark. M-Diffushadow shows the potential to capture and analyze the complex quantum phenomena in quantum many-body systems.

We develop an algorithm to automatically design photonic gates and circuits that is based on a combination of optimization and pruning methods. It starts with a general ansatz for optical circuits with tunable parameters that are then subjected to optimization. The algorithm simplifies the final circuit by pruning its unnecessary elements following predefined criteria. We demonstrate the algorithm by producing both approximate and numerically exact implementations of the cnot gate and Deutsch-Jozsa, Grover, and Fourier transform two-qubit quantum circuits. All implementations of the different gates and circuits can be integrated into larger quantum information protocols.

We consider physics behind the FLASH modality of cancer radiation treatment, where extremely short treatment times are achieved with ultrahigh dose rates maintaining the conventional antitumor effectiveness and yet substantially reducing damage to normal tissues (sparing effect). The difference in responses between normal and tumor tissues is attributed here to the structure transformation rates related to their morphologies: ordered in the normal tissues versus disordered in tumor tissues. Correspondingly different are nonequilibrium charge densities accumulated in the two phases under ionizing radiation. In normal tissues, it is high enough to form a classical electron-hole liquid (EHL). The low EHL diffusivities slow down the generation of biologically active free radicals, hence sparing effect. To the contrary, a disordered tumor tissue renders efficient energy relaxation channels forming free radicals. We describe the FLASH thresholds for doses and dose rates.

Reflection and transmission (tunneling) reveal the wave nature of ultracold matter when scattered from an impurity and are of great importance in atomtronics technology. Using the time-dependent Gross-Pitaevskii equation (GPE), we investigate the trapping, reflection, and transmission of a bright soliton in an ultracold-atom gas propagating through a one-dimensional waveguide with a contact defect. This allows us to analyze the dynamics of the scattering as a function of soliton velocity $v$, the strength of the contact impurity $V_0$, and the intensity of the attractive nonlinear coupling $g<0$. We evolve the GPE numerically with the contact defect modeled as a $\delta$ sequence for the Dirac delta function. We find a universal behavior in terms of $v/V_0$ and $\left|g\right|/V_0$, thus reducing the dimension of the parameter space. Our analysis identifies four distinct regions of nonlinear coupling $\left|g\right|/V_0$ that govern scattering dynamics, delimited by $\left|g\right|/V_0\approx 2$, 4, and 6. Particularly, we observe distinct parameter dependent onsets between the soliton character and highly radiative-dispersive wave packets for the scattering products. To quantify the nature of the scattering products, we use the differential and Fisher information-theoretical measures to determine the degree of localization of the scattering products. The implications of these findings are discussed in the context of both fundamental quantum mechanics and potential experimental setups.

Tailoring light beams in terms of intensity, phase, and polarization distribution has recently garnered significant attention. This work considers vector beams obtained by the natural conical diffraction phenomenon, occurring when a focused light beam travels along one of the optic axes of a biaxial crystal. If a cascade of several aligned biaxial crystals is used, in its sharpest plane this phenomenon usually gives rise to a concentric ring pattern with spatially varying linear polarization, thus covering the equator of the Poincaré sphere. Here, we propose smart arrangements of conical diffraction cascades based on Fibonacci and degenerate sequences leading to vectorial beams addressing multiple areas of the Poincaré sphere. The present approach is based on the concept of path interference and enables a clear spatial separation between regions exhibiting distinct polarization states (linear, elliptical, circular).

The high-extinction cross-polarization measurement of a paraxial laser beam results in a Hermite-Gaussian (${\text{HG}}_{11}$)-like four lobes with a dark-centered cross pattern. The azimuthally spin-separated mode pattern is understood to result from the spin-orbit interaction of light. The perfect dark region at the beam center, due to extreme cross-polarization extinction (EXE), is used here to accurately determine the on-axis residual polarization of the laser beam and, using it, the residual elliptical birefringence of optical crystals. By propagating the laser beam through uniaxial optical crystals with their optic axis cut either parallel or perpendicular to the beam propagation direction and performing the EXE measurement, we demonstrate a simple approach to precisely quantify the residual elliptical birefringence of crystals, which are otherwise assumed to be absent, to a high degree of extinction of 1 part in ${10}^{-8}$. The experimental results are interpreted using Jones-matrix-based calculations for a paraxial laser beam and upon its propagation through the optical crystals. The high sensitivity and high accuracy of the EXE technique make it well suited for measuring and characterizing anisotropy and its dispersion of monolayers, ultrathin films, and two-dimensional materials.

In an open quantum ring (OQR), an asymmetric ring-to-electrode configuration, where the upper and lower arms have unequal lengths, generates antiresonances in the junction transmission spectrum around the doubly degenerate eigenenergies of the isolated ring Hamiltonian. The asymmetric OQR also gives rise to a net circular current transmission within the ring, specifically around these doubly degenerate eigenenergies. We investigate the system-size scaling properties of the transmission within the ring and the overall junction transmission of an OQR. Ballistic transport refers to the unhindered flow of charge carriers within a conductor, where transmission is independent of the system size. Here, we find beyond-ballistic behavior, characterized by an anomalous increase of the transmission with increasing system size, near both the degenerate and nondegenerate eigenenergies of the ring Hamiltonian, depending on the ring-to-electrode configuration. This phenomenon is unique to OQRs and is associated with the quantum interference effect between two counterpropagating electronic waves with nearly equal and opposite momenta. Consequently, there is no equivalent phenomenon in open quantum junctions with linear conductors.