Papers

We propose a method for detecting an ambient density of heavy, electrically-charged particles. Such particles would impact the Earth, lose energy in terrestrial matter, and become trapped. We study the accumulation of these rare particles in multiple target materials that provide large exposure, such as water and geological rocks. We discuss strategies for concentrating the particles by centrifugation or gravitational settling, along with particle identification using mass spectrometry. This method enables the discovery of charged relics with masses $1-10^{12}\,{\rm TeV}$ comprising a tiny fraction of the local dark matter density, reaching down to $f_X\sim 10^{-20}$ at the lowest masses. A pathfinder experiment using only a liter of water and one centrifuge (or $\sim \text{m}^3$ and no centrifuge) operating for a month can already reach $f_X\sim 10^{-10}$ and probe new parameter space.

Strong electromagnetic backgrounds make quantum electrodynamics a real-time nonperturbative problem involving dressed fermions and dynamical photons. We propose a trapped-ion protocol for simulating intense-field QED in $3+1$ dimensions in the Furry picture. The construction encodes photon modes in collective phonons and Volkov-dressed fermion modes in ion spins, combining native spin-phonon couplings with Clifford circuits that compress nonlocal Jordan–Wigner strings. For nonlinear Breit–Wheeler pair production, the protocol has polynomial resource scaling and is benchmarked against exact single-mode dynamics with controlled Trotter errors. With experimentally motivated phonon heating and dephasing, zero-noise extrapolation substantially reduces deviations in photon-survival and pair-production signals. These results provide a hardware-efficient route to intense-field particle-production dynamics beyond perturbative or static-field descriptions.

We study electro-acoustic perturbative modes in homogeneous, isotropic and expanding – dubbed as Friedmann-Lemaitre-Robertson-Walker (FLRW) – Jellium models, thereby mimicking density perturbations in analogous Newtonian cosmological expansions. We present both novel analytic solutions for linear perturbations in specific analogue cosmological expansions and full numerical evaluations that characterize the temporal evolution of the electro-acoustic modes capturing their full dynamical behavior across the linear and the nonlinear regimes. For both the case of pressure supported evolution or modes sourced by nonadiabatic contributions, we also characterize the temporal evolution of such perturbations by introducing their scale dependent particle number fluctuation power spectrum which can act as a tool to connect theory and experiments. The dependence of the latter on the physical parameters of the model is demonstrated in detail.

The black-bounce spacetime provides a regularized modification of the Schwarzschild metric by introducing a free parameter $a$ that eliminates the central singularity while preserving the exterior geometry of a classical black hole. This work investigates the physical implications of this metric across three complementary observational windows. First, we examine the horizon structure and the transition between a regular black hole ($a < 2M$) and a traversable wormhole ($a > 2M$), offering a viable singularity-free alternative to classical black hole solutions. Second, we perform Solar System precision tests perihelion precession of Mercury, gravitational lensing, and the Shapiro time delay of radar signals demonstrating that the bounce parameter $a$ introduces small but measurable corrections relative to general relativity. Third, and for the first time, we apply the black-bounce metric to galactic dynamics by deriving the circular velocity field and fitting it to the observed rotation curve of NGC~7331. A four-component mass decomposition black-bounce central potential, Freeman exponential disc, Hernquist bulge, and a Navarro–Frenk–White dark matter halo yields $a = 1.035 \pm 0.119$~kpc , providing the first observational constraint on the bounce parameter from galaxy kinematics. Our results confirm that the black-bounce metric regularises the inner galactic core while remaining fully consistent with a standard dark matter halo at large radii, establishing this spacetime as a compelling testbed for singularity-free alternatives to classical black holes.

We use Bayesian inference on multi-messenger observations to constrain the parameter space of compact stars in a phenomenological braneworld model inspired by the effective Sahni–Shtanov scenario. Stellar structure is described by modified Tolman–Oppenheimer–Volkoff equations including local quadratic brane corrections and a phenomenological closure for the nonlocal Weyl sector, parametrized by the brane tension $\lambda$, the Weyl coupling $\alpha_{\mathcal{U}}$, and the Weyl equation-of-state parameter $w_{\mathcal{U}}$. Using the SLy equation of state, we perform an affine-invariant ensemble Markov Chain Monte Carlo analysis combining mass–radius posteriors from GW170817 (LIGO/Virgo) and NICER observations of PSR~J0740$+$6620 and PSR~J1231$-$1411. The posterior yields $\log_{10}(\lambda/\mathrm{km}^{-2})=3.98^{+1.52}{-1.44}$ (68%), indicating a large-brane-tension regime where local high-energy corrections are subdominant. The Weyl coupling is constrained to $\alpha{\mathcal{U}}=-0.15^{+0.30}{-0.08}$ (68%), while $w{\mathcal{U}}$ remains weakly constrained, with a 95% credible interval of $[-1.25,,1.02]$. The inferred stellar properties are $M_{\max}=2.30^{+0.14}{-0.08},M\odot$ and $R_{1.4}=13.31^{+0.54}_{-0.57},\mathrm{km}$ (68%), exceeding the corresponding General Relativity predictions for the SLy equation of state. The 95% posterior interval extends into the GW190814 secondary-mass range, although the median and best-fit values remain below it. These results show that a large-tension braneworld with a mildly negative Weyl coupling is consistent with current NICER and gravitational-wave constraints without requiring large deviations from General Relativity.

In AdS/CFT, one often finds claims along the lines that “spacetime emerges from entanglement." This paper argues that behind these general statements hide three distinct emergence claims about, respectively, metric, gravitational dynamics, and topological connectivity. Thus, despite being advertised with the same terminology, these results are not about the same spatiotemporal aspects. They can therefore not just be grouped as evidence for one unanimous conclusion, though they do point in similar directions. The paper also investigates whether the three emergence claims satisfy two of the necessary conditions for emergence: Determination and novelty. The paper argues that none of the emergence claims satisfies the determination condition: More than entanglement is needed to furnish the emergence basis. Besides entanglement, the emergence basis for the bulk metric must include the induced metric on the boundary. Thus, this claim might not satisfy the novelty condition for emergence that the emergent should be novel as compared to the emergence basis. Likewise, the emergence basis for topological connectivity seems to include connectivity whereby this emergence claim is also questionable. The paper concludes that only gravitational dynamics is novel compared to the fully furnished emergence basis.

This article reads two recent tractatus-style texts - Niccolo Covoni and Carlo Rovelli's Tractatus Quanticus (arXiv:2512.06034) and Mikolaj Sienicki and Krzysztof Sienicki's Tractatus de Conscientia (arXiv:2607.05459) - together with Jenann Ismael and Huw Price's interpretive introduction Against Totalitarianism (arXiv:2601.01070), as parts of what may be called a New Tractatus Program. The program is unified by a single pressure point: the demand for a perspective-free description of reality, whether as a final inventory of facts, a world viewed from nowhere, or a self placed outside the physical order. On the relational interpretation of quantum mechanics, Tractatus Quanticus revises Wittgenstein's opening claim by replacing the world as the totality of facts with the world as what is the case from some perspective. Against Totalitarianism then makes the philosophical stakes of this move explicit by challenging the idea of the world as one closed totality. Tractatus de Conscientia carries the same discipline into the theory of consciousness, where conscious experience is treated neither as a mysterious substance nor as mere behavior, but as an integrated, temporally thick, operationally accessible perspective. Read together, these texts point toward a post-classical philosophy of partiality: reality is not abolished, but de-absolutized; consciousness is not mystified, but constrained by access, coupling, memory, and evidence; and the limits of language become inseparable from the limits of perspective. The article does not claim that relational quantum mechanics is the only viable interpretation of quantum theory. It instead develops the philosophical consequences of the relational reading. Its aim is programmatic rather than demonstrative: it does not prove a new ontology, but organizes a family of arguments around disciplined perspective-dependence.

Swarmalators are mobile generalizations of phase oscillators. Introduced to model systems in which sync and self-assembly interact, they remain poorly understood theoretically. Unlike the Kuramoto model for coupled oscillators, existing swarmalator models lack a normal-form foundation, and their basic stabilities and bifurcations remain largely unsolved. Here we address both problems. Building on Tanaka's reduction of chemotactic oscillators, we show that the canonical one-dimensional swarmalator model – previously introduced as an ad hoc toy model – is recovered in the first-harmonic, zero-lag limit, implying its behavior is generic. We then derive the stability boundaries organizing its four collective states, show they meet at a single cusp, correct a previously published order-parameter formula, and uncover a non-monotonic sync response absent in the Kuramoto model.

Cavity optomagnomechanics provides a versatile platform to explore macroscopic quantum correlations, particularly nonreciprocal entanglement. In this work, we propose a theoretical scheme to generate switchable bipartite and tripartite entanglement in an optomagnomechanical ring cavity by exploiting phase-controlled magnon squeezing. Indeed, two spatially separated ferrimagnetic YIG microbridges become entangled through their magnetostriction-mediated coupling to mechanical motion and a common cavity field via radiation-pressure interaction. The squeezing process introduces two phase-dependent contributions to the magnon response, namely an effective detuning shift $\Delta_{\theta_j}$ and a quadrature-damping contribution $\kappa_{\theta_j}$, both of which reverse sign upon a $\pi$ phase shift, providing an in situ control to switch the entanglement response. The nonreciprocal entanglement is defined operationally through the asymmetric entanglement response under the phase reversal $\theta_j \to \theta_j + \pi$, quantified by normalized contrast ratios $C_E$ and $C_{\mathcal{R}}$, which measure the relative difference between the entanglement obtained at $\theta_j$ and at the phase-reversed configuration $\theta_j+\pi$. The resulting phase-tuning method provides a flexible and robust route to achieve high-contrast bipartite and tripartite entanglement within stable parameter regions, establishing magnon squeezing as a practical quantum resource for switchable quantum correlations in hybrid platforms.

We investigate Unruh-DeWitt detectors coupled to composite observables of a quantum scalar field, including quadratic coupling to the field momentum and coupling to the local energy density. We develop a distributional framework for evaluating the corresponding detector response functions and apply it to detectors crossing the Rindler firewall. While we recover the finite response of the derivative-coupling model, we show that quadratic momentum coupling leads to products of distributions that do not admit a canonical, regulator-independent definition in the sharp-firewall idealization. The vacuum correspondence between the local energy-density and quadratic momentum responses motivates the conjecture that analogous difficulties may arise for energy-density coupling in the sharp firewall model. Within the sharp, pointlike composite-coupling model considered here, our analysis further suggests that these pathologies originate from the discontinuous severing of correlations across the Rindler horizon.

Exoplanets are high-value targets for a variety of ground and space-based telescopes. All known exoplanets are Galactic, and a fraction of them orbit compact objects. In this work, we investigate the possibility of detecting extragalactic exoplanets orbiting stellar-mass compact binary coalescences (CBCs), such as binary neutron stars, neutron star-black holes, and binary black holes, using future gravitational wave (GW) detectors, including A+ (LIGO in O5), Einstein Telescope, and DECIGO. We use the technique of reconstructing an external potential's profile by extracting information about the centre-of-mass (CoM) kinematics of a CBC encoded in the GWs it emits. In this work, the external potential is provided by the circum-CBC exoplanet, and the resulting signature on the GW waveform comes from the “wobble” of the CBC's CoM around the CBC-exoplanet barycentre. As a proof of principle, we consider a few example CBCs detectable with future detectors and a range of circum-CBC exoplanet parameters in circular and eccentric orbits. We find that for a significant fraction of the range of parameters considered, we can identify the presence of a circum-CBC exoplanet by extracting its mass (up to an unknown orbital inclination angle) within a factor $\mathcal{O}(1)$ of its true value, at $68\%$ confidence.

We report the confirmation and characterisation of two moderate-period sub-Jovian planets transiting the bright F-type star HD 148797 (G=9.4 mag, Teff=6441 +/- 51 K). Using photometric time series from TESS and CHEOPS, we determine orbital periods of 42.1 d for HD 148797 b and 68.2 d for HD 148797 c, putting the period ratio very close to the golden mean at 1.619 and therefore near several strong harmonics, and measure planetary radii of 8.25 +/- 0.37 RE and 8.37 +/- 0.38 RE, respectively. We detect significant anti-correlated transit-timing variations for both planets, which contain enough harmonic information to yield photodynamical masses of 39.3 +13 -8.5 ME for HD 148797 b and 39.6 +/- 9.3 ME for HD 148797 c. The corresponding bulk densities, 0.39 +/- 0.12 and 0.377 +/- 0.084 g/cm3, place both planets among the low-density sub-Jovians of the Neptunian savanna. The architecture of HD 148797 is not unusual within this regime: we find that detected multi-system fractions in the savanna remain at ~70-90%, and that most savanna multi-planet systems contain at least one adjacent planet pair with Pout/Pin < 3. This pattern suggests that savanna sub-Jovians are commonly found in dynamically cold systems, consistent with smoother migration pathways such as disk-driven migration rather than disruptive high-eccentricity tidal migration. As a bright, co-evolved system hosting two warm savanna sub-Jovians with similar radii and masses, HD 148797 is also a promising target for comparative atmospheric characterisation.

Achieving valley splittings well in excess of the thermal energy of electrons and avoiding valley excitations is essential for the consistent initialization, operation and readout of gate-defined Si spin qubits. In this work, we present a device-level optimization strategy for pushing valley splittings to between 1 and 5 meV, well beyond values reported in nearly all previous theoretical studies. Using device-scale simulations that incorporate atomistic alloy disorder through a 1D tight-binding theory, we demonstrate that our proposed approach yields large valley splittings with a tight distribution across disorder realizations, a key requirement for reproducible qubit performance at scale. The approach rests on an unorthodox Si/SiGe heterostructure design combining a narrow quantum well, a small Ge spike, and a pure-Ge cap. We corroborate these predictions with targeted atomistic density functional theory calculations. These results offer a clear path forward for scalable Si/SiGe spin qubit devices and, if realized experimentally, effectively eliminate valley splitting as an existential problem for large scale SiGe-based quantum processors.

We propose a novel formulation of master equations for open systems wherein the evolution of a state is determined solely by its local behaviour at any point of time. Specifically, our formulation allows for a local interpretation of the workings of beyond-Markovian dynamics as opposed to the more common conception that non-Markovian state evolution is affected by its cumulative past history. Quite interestingly, local determinacy is found prevalent in quantum dynamics. We illustrate the advantages of our coordinate-free formulation with exact analyses on two physically relevant models.

Little Red Dots (LRDs) are a population of compact red sources discovered by the James Webb Space Telescope (JWST). Imaging and spectroscopy have shown that LRDs exhibit a complex spectrum with a “V-shaped" continuum, broad Balmer emission lines, and in some cases Balmer absorption. While the physical origin of these components remains debated, recent studies propose that they arise from a compact central engine likely hosting a rapidly growing black hole embedded within a more extended host galaxy. We test this central engine + host galaxy model using JWST/NIRSpec integral field unit (IFU) spectroscopy to spectrally decompose the observed continuum, narrow and broad emission lines, and absorption. We spatially map each component for five broad Ha-selected LRDs at z~5 observed with both the prism and high-resolution G395H grating. We find that the blue continuum emission is co-spatial with the narrow emission line region, while the red continuum arises from a compact core co-spatial with the broad Balmer emission and absorption. Spatial maps of the [OIII] equivalent width reveal a pronounced decrease in the central core. Our work provides further evidence that the LRD emission is produced by at least two distinct physical components arising from a red central engine embedded within a blue host galaxy.

The centre of mass (CoM) of compact binary coalescences (CBCs) occurring in the vicinity of a supermassive black hole, through interaction with an arbitrary third body (e.g., of stellar mass), or in a dense stellar environment, will undergo a time-varying line-of-sight (LOS) velocity. This in turn leads to a time-varying Doppler shift and corresponding modulations in the shape of the gravitational waves (GWs). The phase and amplitude corrections arising from constant LOS acceleration and its higher-order time derivatives are already known. Specifically, these effects lead to corrections to the GW waveform at $-4n$ post-Newtonian (PN) order, where $n$ is the $n^{th}$ time derivative of the LOS velocity. In the context of a circular or eccentric outer orbit of the CoM of the CBC, these effects can be thought of as approximations to the LOS velocity in the limit: observation duration $\ll$ period of the outer orbit. However, this condition is not necessarily always satisfied. In this paper, we present phase and amplitude corrections to the GW waveforms arising from a periodic non-relativistic LOS velocity for circular and eccentric outer orbits of the CBC's CoM. Specifically, these lead to phase and amplitude modulations at 4 PN order, and reduce to the known corrections for constant kinematic parameters under appropriate limits mentioned above. We also perform a Fisher matrix analysis to forecast constraints on the environment that is sourcing the time-varying LOS velocity, for various future ground and space-based detectors. We further show that constraints acquired using GW waveforms derived in this work improve significantly in comparison to those acquired from approximate methods valid for constant kinematic parameters.

Extending and refining a preceding work, the free evolution of a quantum wave function, with fixed initial and final modulus, is considered in the general case where nodes are allowed. The method is based on considering a suitable simple functional related to the quadratic optimal transport cost in discrete time. Under reasonable assumptions it is shown that, if nodes are present, the free evolution of the wave function with fixed initial and final modulus is a sort of local minimum. If no nodes are present the minimum is global, suggesting intrinsic instability of the nodes in a free quantum evolution.

Partial differential equations are a promising application area for fault-tolerant quantum algorithms, but the subject lies between two communities with different languages: numerical analysis and quantum computation. These lecture notes provide a numerically grounded introduction for readers entering from either field. Block encoding is the organizing principle: once a discretized differential operator is embedded in a unitary, primitives such as quantum singular value transformation, Hamiltonian simulation, linear combinations of unitaries, amplitude amplification, and measurement can be assembled into algorithms for elliptic, hyperbolic, and parabolic PDEs. Each chapter begins with a standard finite difference or finite element discretization and follows the full pipeline from the continuous PDE to quantum encoding, transformation, and extraction of a quantity of interest. Particular attention is paid to the factors governing end-to-end performance, including discretization error, state preparation, normalization, postselection, and measurement cost. A final chapter introduces nonlinear problems through Carleman and Koopman-von Neumann linearizations. The aim is not a comprehensive survey or a claim of universal quantum advantage, but a mathematically transparent entry point and a shared vocabulary for researchers in both communities.

Tunneling is essential in the initialization, measurement, and control of quantum dot qubits. In silicon, such tunneling connects not only the qubit states but also valley minima in the conduction band on opposite sides of the Brillouin zone, with large consequences for the quantum dot behavior. Here we present a full characterization of the intravalley and intervalley tunnel couplings, including their complex phases – the valley phases. These phases are shown to control measurable parameters, including the ratios of the gaps at anticrossings between quantum states of a double quantum dot. The valley phases themselves evolve as a function of the quantum dot gate voltages and depend on the underlying atomic structure of the quantum well. Knowledge of the valley phases completes the picture and fills a key gap in our understanding of sample-wide variations of valley couplings and the physical parameters that depend on them, including spin-orbit coupling, valley-orbit mixing, and Landé $g$-factors.

The cube method reduces conjunction screening in orbital debris simulations to $\mathcal{O}(N)$ cost by evaluating only object pairs sharing the same grid cell at each snapshot, but systematically assigns zero collision probability to pairs separated by a cell boundary at that epoch, a failure known as boundary blindness. This paper introduces the Double Cube (DC) method, which recovers boundary-crossing conjunctions through a spatially shifted secondary grid using bin-index lookup alone, preserving $\mathcal{O}(N)$ complexity. In an isotropic convergence benchmark at $L = 50$ km, DC reduces the blindness rate from $\beta_{\mathrm{Cube}} = 7.09\%$ to $\beta_{\mathrm{DC}} = 0.55\%$, and a synchronized experiment separates the temporal component from the geometric one and leaves DC below $0.01\%$ against $0.80\%$ for the cube. Recovering these pairs changes which pairs are evaluated and leaves the probability formula untouched, so it does not improve calibration by itself, and both uncorrected methods remain substantially miscalibrated, with a reliability slope of $m = 1.1314$ for the cube and $m = 1.0996$ for DC. The formula applies the full cell volume to every evaluated pair irrespective of separation, which is the same bias characterized in the no-time-counter scheme of Direct Simulation Monte Carlo. Two corrections are derived from the geometry of the uniform cell alone: a power-law form referenced to the Robbins mean separation $\bar{d} = 0.6617L$ and a Gaussian form using both that mean and the analytically derived standard deviation $\sigma = 0.2494L$, with no quantity fitted to simulation output. The power-law correction moves the reliability slope to $0.9973$ at $k = 1$ and $0.9429$ at $k = 2$, and the Gaussian correction reaches $0.9806$ with an intercept of $0.975$, the only configuration within $3\%$ of unity on both. Both corrections have been implemented in MOCAT-MC.

Quantum information theory (QIT) characterizes the capabilities and fundamental limits of quantum information processing, underpinning quantum communication, computation, and error correction. Formalizing its coding theorems requires connecting finite-block protocols, analytic inequalities, and asymptotic limits within a unified machine-checked framework. Existing developments, however, lack a reusable operational layer that defines codes, error criteria, achievable rates, and capacities independently of their information-theoretic characterizations. In this work, we present LeanQIT, a Lean 4 library for finite-dimensional QIT. It provides composable, kernel-checked interfaces for quantum states and channels, source and channel codes, finite-block performance criteria, hypothesis testing, one-shot quantities, and asymptotic rate constructions. Using this infrastructure, we formalize Schumacher's quantum source-coding theorem, the Holevo–Schumacher–Westmoreland classical-capacity theorem, and the entanglement-assisted classical-capacity theorem together with its strong converse. By separating operational definitions from analytic characterizations and exposing reusable achievability, converse, and asymptotic components, Lean-QIT provides a machine-readable foundation for formal QIT and a compositional knowledge substrate for emerging AI-assisted formalization, automated proof search, and agentic reasoning in quantum information and computation.

We revisit von Neumann's theory of infinite tensor products of Hilbert spaces. On the set $\Gamma$ of equivalence classes of $C_0$-sequences, which labels the incomplete tensor products inside the complete tensor product, we introduce a natural pseudo-ultrametric $d$: the distance between two classes is the convergence exponent of the series $\sum_j|\langle\varphi_j,\psi_j\rangle-1|$ formed from any pair of representatives. We show that $d$ is well defined on equivalence classes, satisfies the strong triangle inequality, and is complete. Distinct classes may lie at distance zero, so $d$ separates points only after passing to the quotient $\widetilde\Gamma$ of $\Gamma$ by the relation $d=0$; the pair $(\widetilde\Gamma,d)$ is then a complete ultrametric space. As an application, we show that a product unitary $\bigotimes_j U$ whose factor $U$ satisfies $\inf_{\|x\|=1}|\langle x,Ux\rangle-1|>0$ (in particular, a unitary on a finite dimensional space with $1\notin\sigma(U)$) displaces every class to the maximal distance $1$. Guided by the intended application – a caricature of Everettian branching, in which the sectors of the infinite tensor product play the role of worlds – we also develop a gauge-invariant variant $\tilde d$ of the metric, based on von Neumann's weak equivalence and matched to the quasi-equivalence of product states on the quasi-local algebra. The displacement of a class under a product unitary, measured by $\tilde d$, is class dependent and realizes every value in $[0,1]$. We interpret $\tilde d$ as a decoherence exponent: it measures the polynomial rate at which two branches of the universal state vector become operationally distinct as ever larger portions of the environment are monitored.

A search for soft unclustered energy patterns (SUEPs) is conducted using proton-proton collision data corresponding to an integrated luminosity of 127 fb$^{-1}$ at a center-of-mass energy of 13 TeV, collected via the data scouting stream of the CMS experiment at the LHC. Only the results of the high-level trigger reconstruction are recorded to enable a lower threshold on the hadronic activity. This increases the acceptance for SUEP signatures, which are predicted by hidden-valley models with a large 't Hooft coupling. The observed results are consistent with the standard model background prediction. The most stringent limits to date are set on the gluon fusion production of heavy scalar mediators resulting in SUEP-like signals.

Financial and economic history is strewn with bubbles and crashes, booms and busts, crises and upheavals of all sorts. Understanding the origin of these events is arguably one of the most important problems in economic theory: are economies intrinsically unstable, and can one “stabilize unstable economies”? In this review I argue, from a physicist's vantage point, that the concept of equilibrium – so central to mainstream economic thinking – is likely to be the exception rather than the rule in large, complex, interacting systems. Drawing on a series of stylized “toy” models, I show how excess volatility, endogenous crises and crashes, inflation swells and persistent inequalities can all emerge naturally from genuinely out-of-equilibrium dynamics, without invoking large exogenous shocks. Three generic mechanisms recur throughout: trapping in a multiplicity of history-dependent equilibria; the impossibility of dynamically reaching equilibrium, leading to oscillations and chaos; and the spontaneous evolution towards fragile, marginally stable states – the self-organized criticality paradigm. I stress that these are phenomenological scenarios rather than calibrated theories: there is, at this stage, no “smoking gun”. But the burden of proof, I contend, should be on the equilibrium camp.

We expand on the ideas developed by C. Jarzynski in Physica A 552, 122077 (2020), where an integral fluctuation theorem was derived with the aim of obtaining thermodynamic inequalities stronger than those implied by the Jarzynski equality. Restricting ourselves to the quantum setting, we derive the corresponding detailed fluctuation theorem and additional detailed and integral fluctuation theorems; we also provide a clear physical interpretation of the stochastic quantities defined in the previous reference. Furthermore, we show that their averages are given by the nonadiabaticity parameter (i.e., the relative entropy between the final state after a finite-time driving protocol and the corresponding adiabatically evolved state) and the excess work (also known as inner friction). We elaborate on the inequalities derived from the fluctuation theorems and discuss their connection to irreversibility and formulations of the Second Law.

Predicting where floodwater goes and how deep it gets, at high resolution and across large domains, remains computationally expensive with conventional hydraulic solvers, while purely data-driven surrogates are fast but lack physical guarantees and generalize poorly beyond their training events. We present Inunda, a GPU-native flood inundation model that solves the two-dimensional shallow water equations. Inunda uses a mass-conservative local-inertial scheme and runs multi-day events over millions of cells in minutes on a single GPU. Because every operator is autograd-compatible, the solver is differentiable by construction: model parameters can be estimated by gradient descent against gage observations through reverse-mode automatic differentiation of the full simulation. We demonstrate Inunda on three case studies. For a hindcast of Hurricane Harvey (2017) in Harris County, Texas, Inunda matches surveyed high-water marks to a mean absolute error of 0.67 m, competitive with or better than a suite of established flood models, and reaches a median gage water-level Nash Sutcliffe efficiency of +0.72, more than double the +0.31 of the operational National Water Model v3.0. For the July 2025 Central Texas flash flood, Inunda is driven by an 18-member 1-km convection-allowing precipitation ensemble to produce probabilistic flood forecasts whose skill improves systematically as lead time to the crest shortens. For a post-fire flash-flood application in the Rio Ruidoso burn scar, differentiable calibration recovers the saturated hydraulic conductivity as a spatially explicit field at the model's own resolution and traces its multi-year post-fire recovery. Inunda provides an open, end-to-end pipeline for real-event flood modeling that couples the accuracy of physics-based hydraulics with the calibration and coupling advantages of modern differentiable programming.

Current observations reveal persistent tensions with the standard cold dark matter paradigm, raising the question of whether these can be explained by baryonic physics alone or require alternative dark matter models. One such alternative is fuzzy (or wave) dark matter, consisting of ultralight particles with mass $m \sim 10^{-22}$ eV and de Broglie wavelengths on kpc to Mpc scales, which may give rise to large–scale interference patterns in non-linear structures around the cosmic web, such as filaments and clusters. In this work, we search for possible signatures of these interference fringes by investigating periodicities in the distribution of galaxies around cosmic web filaments. To demonstrate our methodology, we compare the filament profiles to a simple model that includes a periodic component of the form $A\cos(2\pi d/ \lambda)$, where $A$ is the maximum density contrast (amplitude) of the periodic component, with wavelength $\lambda=\lambda_0 \cos\theta$ for some face-on wavelength $\lambda_0$ inclined at an angle $\theta$ to the line of sight. Exploiting the large Sloan Digital Sky Survey (SDSS) Main Galaxy Sample, we analyse a sample of 4,394 filaments from the Tempel et al. filament catalogue, each containing at least 10 member galaxies. We find a vast portion of the parameter space is consistent with the observations at the $2\sigma$ level, including all models with $A = 0$ (no periodicity). We identify a region of the parameter space in tension with the observations, allowing us to exclude values of $A > 0.16 \lambda_0 + 0.18$ for $0.2\,\text{Mpc}\,\lesssim \lambda_0 \lesssim 2\,\text{Mpc}$ at the $3\sigma$ level, demonstrating the ability to test models of filament dark matter structure using this methodology.

We consider quasi-one-dimensional (Q1D) continuous waves (CWs) in the two-dimensional (2D) optical system with the cubic-quintic nonlinearity and a Q1D potential trough. In the case of a smooth trough profile, we confirm the known modulational instability (MI) of Q1D CWs with the transverse structure corresponding to the 1D ground state (GS) in the potential trough, and demonstrate the MI of CWs with the dipole-mode (DM) transverse structure, corresponding to the lowest 1D excited state in the potential trough. The CWs of both GS and DM types remain nearly stable close to the edges of their existence regions. Stable stationary states in the form of periodic chains of 2D solitons, trapped in the potential trough, are produced in a numerical form. The dynamics of the soliton chains excited by a localized kick is studied too. For the potential trough with the singular delta-functional profile, we find two species of exact analytical solutions for CWs, one of which is completely stable.

Many production quantum programming languages represent hybrid quantum computations by extending a classical base language with a quantum effect, where qubits are addressed by reference, and quantum operations are understood to mutate some external quantum state. However, the semantics of this view of quantum computation remains underdeveloped, especially when the language allows mid-circuit measurements and non-termination. In this work, we provide a general method for building denotational semantics for such languages, by defining the quantum orchestra monad, which precisely captures this style of quantum effect. The monad has a concrete presentation, being based on the formalism of quantum instruments, a common tool in quantum information theory for capturing the action of a quantum process along with its classical outcomes. It acts on the category DCPO, and so enables the interpretation of divergent hybrid programs. The quantum orchestra monad serves as a natural extension of both the classical state monad and the probabilistic powerdomain monad. We investigate some of the subtleties present when trying to naïvely extend these definitions to the quantum non-commutative case.

We demonstrate a characterisation methodology for a strontium atomic beam, produced by a two-dimensional magneto-optical trap and delivered via a resonant push beam, using fluorescence spectroscopy and time-of-flight (ToF). This provides insight into the beam characteristics of a cold atom source, allowing for direct measurement of the transverse velocity spread, longitudinal velocity distributions, divergence, and the capturable flux for further cooling. From the ToF measurements, we derive a series of flux-per-longitudinal-velocity distributions at varying push saturation parameters ($s_{\mathrm{push}}$) using both a unidirectional and counter-propagating resonant probe beam. A simulation-derived factor is applied to the unidirectional probe longitudinal velocity distribution to account for differences in the scattering rate scaling. The distributions are integrated up to an estimated 3D-MOT capture velocity of \SI{30}{\meter\per\second}. For our system, we find that at $s_{\mathrm{push}} = 0.45$, we obtain a flux of $(1.7 \pm 0.4)\times10^{8}$ atoms/s and $(1.5 \pm 0.4)\times10^{8}$ atoms/s, using a unidirectional probe beam and counter-propagating probe, respectively. These measurements provide a framework for characterising cold atomic sources for applications such as 3D MOT loading and atom interferometers.