Papers

We show that circle-valued spectral values in Tate Rabinowitz Floer homology give rise to quantized energy levels, which recover the quantum mechanical spectrum of a system of uncoupled harmonic oscillators.

We study scaling law of variational quantum algorithms by large-scale numerical experiments on combinatorial optimizations. On experiments up to n = 5000 qubits with O( log(n)) circuit depth with a classically simulable ansatz, the converged energies consistently differ by no more than 0.5% from the optimal or reference energies reported in the benchmarks.

Progress in information processing relies on spintronics, where magnetic states serve as efficient carriers for data storage and transfer. In this work, we theoretically study magnon propagation in a bilayer composed of a ferro-magnet and an antiferromagnet. For this purpose, we probe the spin Seebeck effect by introducing a spatially varying temperature profile. This generates a local magnon excitation and a continuous magnon flux from hot to cold regions which we quantify through the resulting non-equilibrium magnon accumulation. Based on the chirality of these modes, we identify specific constraints for magnon modes traveling either from the ferromagnet into the antiferromagnet or vice versa. A key finding is the observation of a thermally triggered spin current in the antiferromagnet, a phenomenon typically absent in bulk antiferromagnets that obey time-reversal symmetry. These results provide important insights into the design of heterostructures for magnonic chirality-selective spin transport.

We introduce a simple reaction-network model of a quorum-sensing population that couples the cell density $x$ to the signal density $w$. In the four-channel cell-signal network studied here, scaling signal production and removal by the same factor $r$ leaves all deterministic equilibria, and their stability types, unchanged. Nevertheless, we show that $r$ shifts the quasipotential barrier $\Delta V(r)$ for rare transitions towards extinction, and thus, under metastable exit assumptions, the mean time to reach a fixed neighbourhood of the extinction state on the exponential scale $e^{N\Delta V(r)}$. We compute the barrier by minimization of the path action with the signal retained as a fluctuating coordinate, and we check it against mean extinction times obtained without the action solver, i.e., from the backward equation of the jump process on a truncated lattice and from exact stochastic simulation. Over a range of $r$, the minimum-action barriers satisfy $\Delta V(r)=\Delta V_\infty+O(1/r)$, where $\Delta V_\infty$ is obtained by eliminating the signal first, and at $r=1$ the barrier is 55% larger than $\Delta V_\infty$. A formal first-order expansion attributes this increase to the lag of the signal, of which the fluctuations of the signal remove a quarter. The saddle barrier $\Delta V(r)$ is also the least action needed to enter the basin of extinction, whereas the density threshold can be crossed more cheaply, by paths which keep the signal high and are usually followed by recovery. The mean extinction times of the backward equation, which include failed attempts, have a prefactor which tends to a constant, and they grow at a rate within $10^{-5}$ of $\Delta V(r)$ at every tested rate.

We compute analytically greybody factors for d-dimensional large spherically symmetric black holes with Gauss-Bonnet corrections in the high frequency limit. Our calculations include both the eikonal limit, where the real part of the frequency of the scattered wave is much larger than the imaginary part, and the highly damped case,where the imaginary part of the frequency is much larger than the real part, addressing the emission of gravitons and test scalar fields, and yielding full transmission and reflection scattering coefficients. We consider tensorial, vectorial and scalar gravitational perturbations, obtaining the same result for the three cases in the highly damped limit, but not in the eikonal limit.

Quantum process tomography (QPT) protocols are often designed by lifting quantum state tomography (QST) protocols through the Choi-Jamiolkowski isomorphism, at the cost of an extra step enforcing the trace-preserving (TP) constraint. Existing approaches fall into two classes. The folklore partial normalization, which sandwiches the density estimate between inverse square roots of its input marginal, has a closed form but is used as a heuristic, its only analyses being asymptotic and losing a factor polynomial in the dimension. Projection-based methods are principled but have no closed forms and scale poorly with dimension. We resolve this dichotomy by showing that the partial normalization is the exact projection onto the Choi states of quantum channels in fidelity (equivalently in Bures or purified distance). Consequently, any QST algorithm with guarantees in fidelity lifts to a QPT algorithm that inherits its sample complexity, through a single closed-form congruence that preserves the Choi rank and is computed in Kraus form without any eigendecomposition of Choi dimension. We lift two single-copy protocols and prove that the non-adaptive one (Fidelity Projected Least Squares) recovers the Choi rank and reaches infidelity $\varepsilon$ from a number of channel uses proportional to $1/\varepsilon$. Numerically, for channels of low Choi rank, it improves on the state-of-the-art projected least squares in accuracy, and by orders of magnitude in the time and memory of the TP-regularization step and of the returned estimate.

The resolved Kennicutt-Schmidt (KS) relation is a power-law relation between the surface densities of the star formation rate ($\Sigma_\mathrm{SFR}$) and molecular gas ($\Sigma_\mathrm{mol}$) in star-forming galaxies on kiloparsec scales. Despite its apparent simplicity, it exhibits substantial scatter, suggesting the influence of additional physical parameters beyond gas surface density. We investigate whether molecular gas velocity dispersion ($\Delta v$) acts as a hidden parameter in the resolved KS relation in nearby galaxies. We use spatially resolved measurements of $\Sigma_\mathrm{SFR}$, $\Sigma_\mathrm{mol}$, and $\Delta v$ from the ALMaQUEST, EDGE-CALIFA, and PHANGS-ALMA surveys and from observations of the single galaxy M51. We identify two groups of galaxies based on the direction of the $\Delta v$ gradient with respect to the best-fit KS line: one in which the $\Delta v$ gradient is completely aligned with the KS line (group A) and thus does not contribute to the scatter, and one in which it has a component perpendicular to the line (group B) and contributes to the scatter. For each group, we fit the KS relation and examine the dependence of the residuals ($Res$) of the fit on $\Delta v$. In group B, we find a weak but statistically significant correlation between $Res$ and $\Delta v$, which is consistent across all surveys. A three-dimensional fit including $\Delta v$ yields $\Sigma_\mathrm{SFR} \propto \Sigma_\mathrm{mol}^{1.15} \Delta v^{-0.59}$. We conclude that there is a set of star-forming galaxies for which the velocity dispersion acts as a secondary parameter in the KS relation, with higher $\Delta v$ corresponding to lower $\Sigma_\mathrm{SFR}$ at fixed $\Sigma_\mathrm{mol}$. We find no obvious correlation between membership in this set and the other properties examined.

We investigate direct photon and dilepton production in a concurrent minijet-hydrodynamics framework that consistently incorporates event-by-event initial-state fluctuations and dynamical minijet-medium interactions. Produced in initial hard scatterings, minijets thermalize more slowly than the bulk medium and persist into the hydrodynamic stage, where they deposit energy and momentum into the evolving plasma, generating wakes that modify its spacetime evolution. Minijets modify the hadronic multiplicity and momentum anisotropy in a manner that can largely be absorbed by adjusting the shear viscosity and the normalization of the system's initial energy-momentum tensor. In contrast, electromagnetic probes are emitted throughout the evolution and remain directly sensitive to the underlying spacetime history. We perform a comprehensive calculation of direct photon and dilepton production with the minijets and bulk medium evolved simultaneously, using PYTHIA to produce minijets, and describing the underlying plasma with IP-Glasma initial conditions, hydrodynamic evolution with MUSIC and hadronic transport with UrQMD. We find that the minijet-induced modification of the hydrodynamic evolution produces measurable effects in both photon and dilepton observables, establishing electromagnetic radiation as a sensitive probe of the interplay between hard partons and the quark-gluon plasma.

We study equilibrium configurations and linear perturbations of a Lorentz-violating Kalb–Ramond field with a quartic symmetry-breaking potential and a non-minimal Riemann coupling on a fixed Schwarzschild background. The electric equilibrium is determined algebraically by a characteristic function that can develop a finite-radius double root. Approaching this configuration, the electric monopole response scales as $|\widehat e(\omega,r_c)|\propto(\gamma_c-\gamma)^{-1/2}$, while the propagating monopole remains regular. For higher multipoles we obtain the exact axial zero-mode tower $\xi_{\ell n}=-(\ell+n+1)(\ell+n+2)/3$. At $\ell=1$ a complementary static mode gives a second low-frequency branch. Increasing the positive Riemann coupling causes two purely imaginary growing modes to collide and form an oscillatory unstable pair, with square-root real-part splitting. Independent numerical checks confirm that this behavior persists under changes of the equilibrium parameters. The corrected bare sign removes the monopole ghost, but a constrained high-momentum negative-energy direction remains on the asymptotically electric branch. We therefore distinguish the existence of classical growing modes from the stronger requirement of a positive-energy theory.

Discovering properties of many-body quantum systems is challenging because of the large number of parameters to determine. Here, we show that correlations among quantum observables help reduce the complexity of quantum learning. A polynomial number of selected measurements can bound the values of exponentially many dependent yet unmeasured quantities, enabling efficient estimation of general functions of quantum states. We leverage this result to design correlation-informed learning algorithms that estimate key quantum resources, such as entanglement and magic, in systems of 100 qubits. They achieve a lower relative error than shadow tomography and neural-state methods by using information about a polynomial number of measured Pauli strings. These protocols are readily testable with today's quantum computers, as they do not require premeasurement entangling gates. Quantum constraints themselves are therefore a resource for exploring large quantum systems.

Grain boundaries fundamentally dictate the macroscopic properties of polycrystalline materials by breaking long-range symmetry. In ferroelectrics, these structural discontinuities are conventionally considered as detrimental features that induce depolarization fields and accumulate defects, thereby suppressing or pinning local polarization. Here, we demonstrate that the commensurability of grain boundaries inherently governs the polar-orthorhombic phase stability in polycrystalline Hf0.5Zr0.5O2 (HZO) thin films. Using depth-resolved multislice electron ptychography, we map the three-dimensional (3D) phase distribution across diverse boundaries with atomic resolution, revealing that highly commensurate grain boundaries effectively suppress the nonpolar-tetragonal phase by compensating for lattice mismatch while mitigating geometric frustration. Monte Carlo simulations uncover the atomistic and energetic origins of polar-phase stabilization, showing that commensurate grain boundaries favor the polar-orthorhombic phase more strongly than other grain boundaries. Guided by this principle, we epitaxially engineer HZO thin films to promote the preferential formation of commensurate grain boundaries, resulting in an approximately 60% enhancement in the remanent polarization of ferroelectric devices. These findings provide direct 3D experimental and theoretical evidence that establishes grain boundary commensurability as a critical degree of freedom for designing functional interfaces, guiding the construction of novel ceramics and polycrystalline ferroelectrics.

We construct modular-invariant torus partition functions with a unique vacuum, discrete energy levels and positive integer degeneracies by recursively repairing the Maloney–Witten–Keller modular completion of the Virasoro vacuum. Exact modular repairs and finite moment matching discretize successive spectral bands while preserving earlier levels and controlling convergence. For $c_L=c_R=c$ and $a=(c-1)/12$, the construction realizes primary dimension gaps $\Delta_1=(1+\kappa)a$ for sufficiently small fixed $\kappa>0$, and $\Delta_1=a+\delta$ for any fixed $\delta\ge0$, at every sufficiently large real $c$. Every nonvacuum primary satisfies $h,\bar h\ge(c-1)/24$. In the fixed-$\delta$ family, spectra can be chosen whose densities of states, smoothed with a fixed nonnegative normalized smooth kernel of compact support, match the correspondingly smoothed prediction of a single perturbative BTZ saddle through every fixed finite order in $1/c$. The count includes all spins and Virasoro descendants. Its logarithm reproduces the Bekenstein–Hawking entropy and its corrections at every fixed positive $E/c$, where $E=\Delta-c/12$. This includes $0<E<c/12$, where thermal AdS dominates the canonical ensemble.

Generally, ultrafast laser glass dicing is governed by explosive material removal, which restricts the achievable surface roughness. Here we report single-step dicing of aluminosilicate glass with residual interface roughness below 5 nm, producing optical-quality surfaces without post-processing, using near-field-enhanced 0th-order Bessel-Gauss beams. This exceptional interface quality cannot be explained by a conventional laser ablation mechanism, such as phase explosion, melt expulsion, or fracture-dominated material removal. Instead, quantitative analysis of local thermal dynamics indicates that material removal is consistent with a Hertz-Knudsen-type evaporation process, enabling layer-by-layer removal with precision approaching a few molecular layers. These results suggest that nanoscale optical confinement fundamentally alters the response of transparent materials to ultrafast laser irradiation and establish a route toward deterministic laser processing with near-atomic precision.

The search for massive compact objects such as black holes (BHs) or neutron stars (NSs) in star clusters is longstanding challenge in astrophysics, yet no definitive identification of such compact objects in young clusters has been reported. In this Letter, we construct a sample of high-priority candidates for follow-up investigation. By cross-matching the cluster catalog with the Gaia Non-Single-Star database and estimating companion masses, we identify 13 systems with companion masses exceeding 1.4~$M_{\odot}$, three of which have masses above 2.1~$M_{\odot}$. Applying our newly developed Astrometric Mass-Ratio Function (AMRF) classification based on cluster-specific isochrones, we identify three systems whose companions cannot readily be explained by a single main-sequence star or an unresolved close binary. These systems have inferred companion masses exceeding 2.1~$M_{\odot}$, suggesting that they may be high-mass compact-object candidates. Joint Gaia and radial velocity orbit fitting for a comparison subset yields companion masses broadly consistent with the astrometric estimates, supporting the use of our framework for target prioritization. These unconfirmed systems are valuable targets for multi-epoch spectroscopy, high-resolution imaging, and future Gaia epoch astrometry.

DESI DR2 baryon acoustic oscillation measurements have sharpened a discrepancy with cosmic microwave background (CMB) inferences that can be recast as a preference for a reionization optical depth of $\tau_{\rm reio}\simeq 0.09$, well above the $\simeq 0.06$ inferred from large-scale CMB polarization measurements. Here we test whether electromagnetic energy injection from dark matter (DM) decaying through $\chi\rightarrow e^{+}e^{-}$ can provide this additional optical depth. Adopting a Gompertzian model for astrophysical reionization, which provides an asymmetric, simulation-calibrated description of cosmic reionization, we derive $\tau_{\rm reio}$ self-consistently from the evolution of the free-electron fraction, including the contribution from DM decay. We jointly constrain cosmological and reionization parameters and the DM decay rate using ACT+Planck CMB temperature and polarization anisotropies, CMB lensing, BAO measurements, and quasar damping-wing observations. For $m_\chi=1\,{\rm GeV}$, DM decay raises the marginalized optical depth from $\tau_{\rm reio}=0.064$ to $0.072$, but does not significantly improve the fit. The additional optical depth arises primarily from a broad ionization tail extending through the cosmic dark ages, rather than from an earlier onset of astrophysical reionization. Across $m_\chi=2\,{\rm MeV}$–$7\,{\rm GeV}$, the central $68\%$ credible intervals remain below the $\tau_{\rm reio}\simeq 0.08$ level previously found sufficient to bring both the neutrino-mass tension and the exclusion of $\Lambda$CDM below the $2\sigma$ level. The corresponding DM lifetime constraints are complementary to cosmic-ray and gas-heating bounds and competitive with previous CMB limits. Decaying DM therefore shifts the inferred optical depth in the direction required to ease the CMB–BAO discrepancy, but the allowed increase remains insufficient to alleviate it substantially.

Montanaro and Zhou proved that depth-one Quantum Approximate Optimization Algorithm (QAOA) finds the planted solution of certain near-symmetric constraint satisfaction problems with probability $\Omega(1)$, and observed exponential runtimes for general-purpose classical solvers on explicit realizations, providing strong evidence of an empirical exponential speedup of low-depth QAOA. We ask what such a circuit costs fault-tolerantly. Although the cost Hamiltonian carries $\Theta(n^\ell)$ clauses, the rotation angle at which QAOA succeeds shrinks as $n^{1-\ell}$, and we show that small-angle Clifford$+T$ rotation synthesis reduces the non-Clifford cost per circuit to $\widetilde O(n^2)$ for every clause locality $\ell$. Compiling the circuit, however, requires the explicit clause list. We find that the mechanism underlying constant QAOA success fixes the degree-one Fourier coefficients of the cost, whose signs reveal the planted solution. However, this leakage need not reveal the solution: we design families in which the quadratic non-Clifford scaling and hard exact optimization coexist.

A central question in the theory of quantum advantage is whether there are quantum advantage protocols with similar resource requirements as random circuit sampling that are also verifiable just from the classical outputs of the quantum computation. Here, we develop the idea of simulation secrets for verifiable advantage. A verifier can use a simulation secret to evaluate a cross-entropy test faster than it would take a classical adversary to pass the test. We instantiate this idea using IQP circuits described by cubic polynomials with planted independent spaces. These correspond to the largest independent set in the orbit of a polynomial under the general linear group and yield a low-rank stabilizer decomposition of the corresponding state. We conjecture that large independent spaces are invisible to a computationally bounded adversary, and therefore they cannot exploit them to pass the protocol. A second conjecture regards the fine-grained complexity of producing samples that pass the cross-entropy test for uniformly random polynomials. Under these conjectures, our scheme results in a polynomial gap between the verification time and the time a classical adversary would need to pass the protocol—both are exponential. It has a potential application to generating classically certifiable randomness, since the output distributions have high min-entropy. We estimate that the planted polynomial scheme is implementable using 100 logical qubits at logical error rates around $10^{-6}$.

We introduce an entanglement distillation protocol that utilizes an arbitrary $[[n,k,d]]$ stabilizer code to convert $n$ raw copies of an $N$-qubit Greenberger-Horne-Zeilinger (GHZ) state into $k$ logical copies in the presence of Pauli noise. Our explicit formulation of the scheme on a star network topology is efficiently scalable to arbitrary $N$, requires only local operations, and minimizes the impact of errors on idle physical qubits, enabling the distribution of high-fidelity entangled logical states between any number of quantum processors. We report the results of numerical experiments using the 5-qubit code, toric code, and $[[144,12,12]]$ bivariate bicyle code to protect against independent single-qubit depolarizing noise on all qubits. Our encoding scheme improves the final GHZ state fidelity relative to a single bare GHZ state sent over the same noisy channel for depolarizing rates up to or above $6 \%$ for all codes tested. Additionally, we use the stabilizer formalism to prove that our protocol can be applied to any $N$-qubit Calderbank-Shor-Steane (CSS) stabilizer state, from which the GHZ state emerges as a special case. This result explicitly establishes the working principle of previous stabilizer-based Bell pair and GHZ state distillation schemes, and generalizes such protocols beyond the traditionally considered states. We also show that some stabilizer codes can distill any stabilizer state with our protocol.

Traditional simulations of parametric partial differential equations (PDEs) rely on repetitive computations for each parameter, which makes high-fidelity design impractical. Neural operators address this issue by learning solution operators, accelerating parameter-space mapping by orders of magnitude. Recent Transformer-based neural operators attempt to capture global dependencies, but often at the cost of quadratic attention complexity. Transolver resolves this problem by projecting physical states into a reduced slice space for attention computation. Although fast, this projection sacrifices fine spatial information. Moreover, by operating in this reduced space with shared weights across attention heads, it may constrain the model's flexibility, thereby limiting its capacity to capture complex phenomena. To address these issues, we propose the Cluster Attention Neural Operator (CANO), which reformulates attention via a novel cross-attention mechanism that dynamically clusters queries while preserving full-resolution keys and values. This avoids slice compression loss and removes weight-sharing limits. At the same time, the model remains fast without losing global interactions. Empirically, CANO achieves state-of-the-art performance across canonical PDE benchmarks, covering fluid and solid dynamics (e.g., Navier-Stokes, Airfoil, Plasticity), irregular unstructured geometries (e.g., Pipe Turbulence, Composites), and long-term temporal rollouts. Across solid deformation and turbulent flow benchmarks, CANO achieves lower errors than baselines and exhibits strong geometric adaptability and temporal consistency.

In many 5D extensions of the Standard Model, the Higgs boson is localised to a single point along the extra dimension, where it couples to bulk fermions. Computing the fermion mass spectrum then requires a boundary regulator, and removing it before or after summing the Kaluza-Klein tower can give different answers, as shown in Ref.~\cite{Barcelo:2014kha}. Because the coupling reaches any KK mode through only two overlap numbers, the whole tower can be eliminated exactly by a Schur complement; the disagreement between the two orders of limit then reduces to a single sum, whose discontinuity we prove directly. This discontinuity needs two conditions to appear: a coupling sharp enough to leave the sum conditionally convergent, and a second channel with complementary behaviour at the point of contact. Neither condition depends on having an extra dimension, or even a discrete tower to sum. The same test applies to contact interactions in ordinary scattering, the imaginary part behind the optical theorem, and seesaw, portal, and clockwork constructions. Whether the two conditions are met determines whether a similar ambiguity plays any role.

We introduce the notion of stochastically evolving Hamiltonians (SEHs), which are local Hamiltonians whose coefficients are governed by stochastic differential equations (SDEs). After developing some theoretical aspects of these objects, we consider the task of Hamiltonian learning for SEHs. We reanalyse and make necessary extensions to the Huang-Tong-Fang-Su protocol, which first achieved the Heisenberg limit for Hamiltonian coefficient learning, under these circumstances. We delineate theoretically the regimes where the Heisenberg limit can and cannot be retained. Along the way we develop a few tools in quantum sensing and Hamiltonian simulation that may be of independent interest under similar settings in quantum information processing. The broad aim is to encourage the exploration of various settings in quantum information processing in which the control parameters are governed by SDEs.

Stellar age is the central desirable parameter we need to disentangle different Galactic formation scenarios. Nevertheless, no stellar age dating method is completely model-independent. Even in the best-case scenarios, present-day stellar age estimates are only precise to $\sim7\%$ and accurate to $\sim10-15\%$. A main drawback of state-of-the-art stellar parameter inference codes like StarHorse is that they do not take into account unresolved stellar multiplicity. Especially in the case of nearly equal-mass binaries or higher-order systems on the main sequence, properly taking into account unresolved multiplicity is imperative for the next generation of stellar surveys. Simulation-based inference (SBI) is a robust and flexible approach for dealing with complex models where traditional likelihood-based methods become unfeasible. Here we sketch how SBI can be used to obtain precise stellar ages, masses, binary mass ratios, and other stellar parameters from spectroscopic, photometric, and astrometric measurements.

We compute the first-order incoherent backscattering cross-section of a rough surface over a half-space with randomly fluctuating permittivity, when the two random fields are correlated, so that surface and volume scattering are not additive. A non-orthogonal coordinate transformation flattens the rough boundary and turns the geometric roughness into volume sources of the same Helmholtz equation as the dielectric fluctuations, propagated by the same Green's function: both mechanisms and their interference follow from one calculation, with no equivalent surface currents and no prescription for the field discontinuity. The geometric part of the amplitude reproduces the small-perturbation kernel exactly, for any incidence angle, permittivity and profile function. The interference term is obtained for both co-polarized channels, with an explicit surface-dielectric correlation coefficient. The departure from additivity reaches twenty percent at full correlation, changes sign with that coefficient, and is governed by a balance condition and a coherence condition on the depth of the correlated layer. It carries no angular signature and shifts the co-polarized ratio by less than a tenth of a decibel, so an additive inversion absorbs it, biasing the retrieved amplitude of the dielectric fluctuations by tens of percent.

We derive a closed expression for the $1/c_{M}$ correction to highest-weight BMS$_3$ blocks with four light external primaries of generic weights and non-vacuum exchange. With $c_L$ and all operator weights held fixed, we prove that the global sector and descendants containing exactly one non-global generator $L_{-n}$ or $M_{-n}$ with $n\geq2$ suffice through this order. This truncation reduces the intrinsic calculation to global blocks and their derivatives, whose contributions we resum for nonzero exchanged boost weight $\xi_{p}$. For pairwise identical external operators, we independently reproduce the correction through the introduction of boundary gravitons in the normalized three-point functions in the shadow representation, while keeping the exchanged two-point function fixed. The analogous prescription also reproduces the known non-vacuum Virasoro correction at order $1/c$. For the same external configuration, a formal ultra-relativistic contraction of Virasoro blocks with one flipped chiral representation provides a further check: it yields the same correction, and we prove that contraction commutes with extraction of the $1/c_{M}$ coefficient at each fixed descendant level. The degenerate exchange with $\xi_{p}=0$ requires a separate quotient construction and is not obtained as a smooth limit of the generic block, which we discuss in the appendix.

Routing unknown quantum information across distributed communication networks requires autonomous, measurement-free mechanisms to prevent wave-function collapse. Szegedy quantum walks provide a mechanism for spatial state transport. The conventional walks on unweighted graphs suffer from severe back-reflection, spatial dispersion, and channel crosstalk. In this paper, we introduce a deterministic topological quantum routing architecture based on coined Szegedy quantum walks on edge-duplicated signed graphs. By treating edge signs as localized phase shifts within a balanced coin reflection, we enforce an exact zero back-scattering condition across routing nodes. We demonstrate deterministic Perfect State Transfer (PST) with unit fidelity at exact arrival times across fundamental archetypes, including the signed dumbbell switch $D_{2m,0,2n}$ and scalable glued binary trees. Furthermore, we analyse routing performance under realistic open-system amplitude and phase damping noise channels.

We investigate the chiral separation effect (CSE) and the axial-partner susceptibility splittings within the three-flavor Nambu–Jona-Lasinio (NJL) model, providing two complementary aspects of axial dynamics in hot and dense magnetized matter. We compare a field-dependent scalar coupling, which leads to inverse magnetic catalysis (IMC), with a constant coupling, which exhibits magnetic catalysis (MC). In the weak-field limit, the CSE conductivity is suppressed at low temperature and approaches its chiral-limit value as the temperature increases. Its magnetic-field dependence is reversed between the IMC and MC scenarios. On the other hand, the susceptibility splittings $\Delta_A = \chi_{\pi^0} - \chi_{\delta^0}$ and $\Delta\chi = \chi_{\pi^0} -\chi_{\sigma_l}$ are suppressed at high temperature or density, reflecting the substantial restoration of axial symmetries. Their difference develops a pronounced peak near the cross-over or first-order transition, implying that the $U(1)_A^{(0)}$ and $U(1)_A^{(3)}$ symmetries are restored at different temperatures or chemical potentials. Both the weak-field CSE and the IMC susceptibility splittings at vanishing chemical potential agree qualitatively with lattice-QCD calculations. We also provide model predictions for the susceptibility splittings at finite density.

The efficacy of advanced cycling helmet technologies under youth-specific impact conditions remains unclear. We evaluated how helmet technologies affect head kinematics and concussion risk and whether helmet deformation and helmet-headform relative rotation contribute to protection. Six youth bicycle helmet technologies were tested, including two conventional EPS controls (FOAM-A, FOAM-B) and four advanced technologies (CELL, SLIP, SLIDE, HYDRAULIC). Helmeted headforms were impacted at three locations using a 25 degree anvil at 2.9 m/s, and a 45 degree anvil at 5.2 m/s. Peak linear acceleration (PLA), peak rotational acceleration (PRA), and YGAMBIT-predicted concussion risk were quantified. Stereo high-speed videography measured anvil-normal headform displacement to approximate helmet deformation, and helmet-headform relative rotation. Helmet technology significantly affected predicted concussion risk under both conditions. At 2.9 m/s, all advanced technologies reduced risk relative to FOAM-A, while only SLIDE and HYDRAULIC reduced risk relative to FOAM-B. At 5.2 m/s, all advanced technologies reduced risk relative to both foam controls. HYDRAULIC produced the lowest risk in both conditions, reducing mean risk by 94-95% and 77-78% relative to the foam controls at 2.9 and 5.2 m/s, respectively. CELL, SLIP, and SLIDE significantly reduced PRA across both conditions, whereas HYDRAULIC significantly reduced both PLA and PRA. Greater anvil-normal headform displacement was associated with lower PLA, and greater relative rotation with lower PRA; both independently contributed to lower predicted concussion risk. Advanced technologies in youth cycling helmets can reduce youth concussion risk, but effectiveness depends on impact condition and mitigation mechanism. Designs maximizing controlled helmet deformation and rotational decoupling may provide robust protection in youth-relevant impacts.

Radiative proton capture on ${}^{12}\mathrm{C}$ to the ground state of ${}^{13}\mathrm{N}$ is calculated in cluster effective field theory through next-to-leading order. At low energy the reaction is dominated by $s_{1/2}\to p_{1/2}$ $E1$ capture, which we treat in the long-wavelength limit. Its amplitude is strongly hindered by destructive interference between the contribution fixed by gauge invariance and a counter-term $E1$ current, making the capture particularly sensitive to subleading terms. We fit the recent data below $0.95$~MeV, determining the $E1$ transition counter-term coefficients together with the ground-state asymptotic normalization coefficient and the $\frac{1}{2}^+$ resonance and shape parameters. We obtain $S(0)=1.34\pm0.07$~keV\,b and $S(25~\mathrm{keV})=1.43\pm0.07$~keV\,b, the latter in agreement with recent $R$-matrix extrapolations. We also estimate the effects of the omitted $p$-wave $M1$ capture and $\frac{3}{2}^-$ resonance tail, and find that the fitted asymptotic normalization coefficient moves substantially while the $S$ factors remain almost unchanged.

We introduce a classification of quantum phases of mixed states based on the ability to preserve and fault tolerantly transfer information. We formulate phase equivalence between sets of states that encode logical quantum information and are connected by shallow local channel circuits assisted by local measurements and global classical communication of measurement outcomes, where all quantum operations, including measurements, must be robust to noise. We show that the existence of a recovery threshold for local noise is a property of an entire phase. We prove that any two sets of states with nonzero thresholds that are related by finite-depth local channel circuits belong to the same fault tolerant phase. Our approach leads to a classification of subsystem codes without favoring any state of the gauge subsystem, and we demonstrate phase equivalence between 2D and 3D color codes using dimensional jumps within the 3D gauge color code. Lastly, we study how syndrome structure affects fault tolerance in circuits with measurements. We show that qudit stabilizer codes with extended syndromes permit single-shot state preparation, whereas a broad class of shallow circuits measuring point-like syndromes, including state preparation for 2D topological codes and non-Abelian topological orders with solvable anyon theories, is not fault tolerant.

Two-dimensional materials are promising candidates for electronic applications beyond the operating limits of conventional semiconductor technologies. Within this class, transition-metal dichalcogenides offer attractive properties for field-effect transistor operation, with tungsten disulphide (WS$_2$) emerging as a particularly promising material for operation at cryogenic temperatures. Here, we investigate the electrical performance of a back-gated multilayer WS$_2$ transistor at deep cryogenic temperature, down to 20 mK. The device remains strongly gate-tunable throughout the cryogenic regime, with an effective on/off current ratio exceeding $10^{5}$. Most notably, the low-temperature turn-on characteristics exhibit reproducible shoulder-like features, which we describe using a phenomenological model comprising multiple effective conduction branches operating in parallel.