Private remote quantum sensing aims at estimating a parameter at a distant location by transmitting quantum states on an insecure quantum channel, limiting information leakage and disruption of the estimation itself from an adversary. Previous results highlighted that one can bound the estimation performance in terms of the observed noise. However, if no assumptions are placed on the channel model, such bounds are very loose and severely limit the estimation. We propose and analyze a private remote sensing protocol using—for the first time, to our knowledge—continuous-variable states in the single-user setting. Assuming a typical class of lossy attacks and employing tools from quantum communication, we calculate the true estimation error and privacy of our protocol, both in the asymptotic limit of many channel uses and in the finite-size regime. Our results show that a realistic channel-model assumption, which can be validated with measurement data, allows for a much tighter quantification of the estimation error and privacy for all practical purposes.

The recent evidence for a stochastic gravitational wave background (GWB) in the nanohertz band, announced by pulsar timing array (PTA) collaborations around the world, has been posited to be sourced by either a population of supermassive black holes binaries or perturbations of spacetime near the inflationary era, generated by a zoo of various new physical phenomena. Gravitational waves (GWs) from these latter models would be explained by extensions to the standard model of cosmology and possibly to the standard model of particle physics. While PTA datasets can be used to characterize the parameter spaces of these models, energy conservation and limits from the cosmic microwave background (CMB) can be used a priori to bound those parameter spaces. Here we demonstrate that taking a simple rule for energy conservation and using CMB bounds on the radiation energy density can set stringent limits on the parameters for these models.

In four decades of string theory research, only a handful of nonsupersymmetric tachyon-free strings with only one neutral scalar at tree level were found. We construct new nonsupersymmetric tachyon-free string theories using asymmetric orbifolds that serve as the lower-dimensional counterparts to the $\mathrm{O}(16)\times \mathrm{O}(16)$ string in 4, 6, and 8 dimensions, each featuring only one neutral scalar at tree level, chiral matter and positive leading order potential. The 4D construction uses a quasicrystalline orbifold.

We propose a method to reconstruct the metric and its arbitrary-order derivatives at the horizon for any static, planar-symmetric black hole, using an infinite set of discrete pole-skipping points in momentum space where the boundary Green’s function becomes ambiguous. This method is fully analytical and involves solving only linear equations. The near-horizon reconstruction can extend either inside or outside the horizon until reaching the nearest singularity in the complex radial plane. It further enables a reinterpretation of any pure gravitational field equation in pole-skipping data. Moreover, our method reveals that the pole-skipping points are redundant: only a subset is independent, while the rest are fixed by an equal number of homogeneous polynomial constraints. These identities are universal, independent of the details of the bulk geometry, including its dimensionality, asymptotic behavior, or the existence of a holographic duality.

We present the first ab initio lattice calculations of the proton-rich tin isotopes ${}^{99}\mathrm{Sn}$ to ${}^{102}\mathrm{Sn}$ using nuclear lattice effective field theory with high-fidelity two- and three-nucleon forces. For a given set of three-nucleon couplings, we reproduce binding energies with $\sim 1\%$ accuracy for the even–even systems and obtain energy splitting and two-nucleon separation energies in agreement with experiment. Our results confirm the $N=50$ shell closure and reveal that the binding energy of ${}^{99}\mathrm{Sn}$ lies below values extrapolated from heavier isotopes.

X-ray cavity quantum optics with inner-shell transitions has been limited by the spectral overlap between resonant and continuum states. Here, we report the first experimental demonstration of cavity-controlled core-to-core resonant inelastic x-ray scattering (RIXS). We suppress the absorption-edge effects by monitoring the RIXS profile, thereby resolving the resonant state from the overlapping continuum. We observe distinct cavity-induced energy shifts and cavity-enhanced decay rates in the $2p3d$ RIXS spectra of ${\mathrm{WSi}}_2$. These effects, manifesting as stretched or shifted profiles in the RIXS planes, enable novel spectroscopic applications via cavity-controlled core-hole states. Our results establish core-to-core RIXS as a powerful tool to manipulate inner-shell dynamics in x-ray cavities, offering new avenues for integrating quantum optical effects with x-ray spectroscopy.

Achieving superradiant lasing with an ultranarrow linewidth is crucial for enhancing atomic clock stability in quantum precision measurement. By employing the exceptional point (EP) property of the system, we demonstrate theoretically superradiant lasing with linewidths in the $\mathrm{\mu }\mathrm{Hz}$ range, sustained at the high-power level. This is achieved by incoherently pumping optical lattice clock transitions with ultracold alkaline-earth strontium-87 atoms in the EP of a $\mathcal{P}\mathcal{T}$-symmetric system. Physically, the atomic coherence reaches a maximum in the EP, significantly amplifying the superradiance effect and resulting in superradiant lasing with an ultranarrow linewidth. This linewidth is even three orders of magnitude smaller than that of superradiant lasing in the systems without EP. Our Letter extends the realm of superradiant lasing by introducing the EP property, and offers promising applications for developing atomic clocks with exceptional stability and accuracy.

The solution of interstitial nonmetallic solutes (INSs) like H, He, O, C, N, P, and S is common in refractory high-entropy alloys (RHEAs) and essentially controls the RHEAs properties. However, the disorder local chemical environments of RHEAs hinder the quantitative prediction of the stability of INSs and the understanding of the underlying mechanism. Based on the tight-binding models, we propose an analytic model for determining the solution energy of INSs in RHEAs. This predictive model identifies that the energetics of INSs depends linearly on the $d$-band width of their neighbors, with the slope determined by the bonding characteristics of INSs. Our scheme provides an electronic-level understanding of INSs in RHEAs and explains key experimental observations, which can serve as an effective tool for designing advanced RHEAs.

Localization of coherent propagating waves has been extensively studied over the years, primarily in homogeneous random media. However, significantly less attention has been given to wave localization in media with inhomogeneous disorder, where the standard picture of Anderson localization does not apply, as we demonstrate here. We fabricate photonic lattices with inhomogeneous disorder, modeled by heavy-tailed $\alpha$-stable distributions, and measure the output light intensity profiles. We demonstrate that the spatial localization of light is described by a stretched exponential function, with a stretching parameter $\alpha$, and an asymmetric localized profile with respect to the excitation site. We support our experimental and theoretical findings with extensive tight-binding simulations.

This Letter aims to understand how quantum mechanics affects heat transport at low temperatures. In the classical setting, by considering a simple paradigmatic model, our simulations reveal the emergence of negative differential thermal resistance: paradoxically, increasing the temperature bias by lowering the cold bath temperature reduces the steady-state heat current. In sharp contrast, the quantum version of the model, treated via a Lindblad master equation, exhibits no negative differential thermal resistance: the heat current increases monotonically with thermal bias. This marked divergence highlights the fundamental role of quantum effects in low-temperature thermal transport and underscores the need to reconsider classical predictions when designing and optimizing nanoscale thermal devices.

A unit cell represents the smallest repeating structure in solid-state physics and serves as the fundamental building block of a material. In iron-based superconductors, each unit cell contains two iron atoms, which form two sublattices in the two-dimensional iron layers. Under normal circumstances, these sublattices are expected to have identical physical properties due to space inversion symmetry. However, we discover that this sublattice structure can introduce a novel degree of freedom for probing unconventional pairing mechanisms in iron-based superconductors. We observe distinct dual tunneling spectra within the pairing gap energy corresponding to the two sublattices in the monolayer FeSe with atomically homogeneous ($1\times 1$) structures on ${\mathrm{SrTiO}}_3(001)$ substrates—a phenomenon we term sublattice dichotomy. This dichotomy can be quantitatively explained by a parity-breaking superconducting state, characterized by the coexistence of conventional pairing and interband odd-parity pairing. The interband singlet pairing arises due to the lack of inversion symmetry, which is naturally broken from the interface coupling between the FeSe and ${\mathrm{TiO}}_2$ layer.

We theoretically demonstrate that sufficiently strong magnetoelastic coupling can change the ground state of otherwise uniform spin systems to chiral spin configurations. More specifically, we show that a periodic array of chiral spin textures can spontaneously emerge in a two-dimensional ferromagnetic system on a substrate—even in the absence of Dzyaloshinskii-Moriya interaction. The resulting spin texture resembles a skyrmion-antiskyrmion lattice, characterized by alternating scalar spin chirality and a nonuniform but sign-preserving out-of-plane spin profile. Our analysis reveals that such patterns form naturally when the magnetoelastic interaction is sufficiently strong, while the coupling between flexural phonons and the substrate is sufficiently weak. These findings uncover a previously unexplored mechanism for chiral spin texture formation driven purely by magnetoelastic coupling, signaling potential utilities of materials with strong magnetoelastic responses.

The generation of indistinguishable single photons is a fundamental requirement for photonic quantum technologies. However, spectral fluctuations, often induced by charge noise in epitaxial quantum dots (QDs), lead to exciton dephasing, thereby limiting their practical usage in quantum applications. We present a straightforward approach to mitigate charge noise-induced decoherence in droplet-etched GaAs QDs embedded in an $n\text{−}i\text{−}p$ diode structure and integrated deterministically into an electrically contacted circular Bragg grating resonator for emission enhancement. The quantum device allows for the stabilization of the charge environment by applying an external electrical field while producing a photon extraction efficiency of $(37\pm 2)\%$. Hong-Ou-Mandel two-photon interference measurements reveal a strong dependence of the exciton dephasing time and interference visibility on the applied bias, in excellent agreement with our theoretical predictions. Notably, the reduction in visibility from a maximum, charge stabilized corrected value of 97% at the optimum bias point follows an inverse square dependence ($\propto 1/I^2$) with increasing diode current ($I$) in the forward direction. Under a quasi-resonant excitation scheme, we achieve a maximum exciton dephasing time $(T_2^{*})$ of approximately ($6.8\pm 0.5$) ns, reaching nearly the Fourier limit ($T_2=2T_1$) without the need for complex echo schemes like Ramsey or Carr-Purcell-Meiboom-Gill sequences. These findings are consistent with theoretical predictions from rate equation modeling and quantum optical analysis, as well as voltage-dependent linewidth measurements, demonstrating optimized electrical control of exciton dephasing.

We develop a diagrammatic approach analyzing Gibbs measures (i.e., Bayesian posteriors) in deep shaped multilayer perceptrons at arbitrary temperature. This gives the first (perturbatively) solvable model of learning with nonlinear neural networks where the input dimension $N_0$, depth $L$, width $N$, and number of samples $P$ can all be large without severe assumptions on either initialization or training data statistics. The limits $N_0,N,L,P\to \infty$ do not commute, resulting in a rich phase diagram of learning regimes that we study to first order in $1/N$. We find in particular that the ratio $LP/N$ defines a critical depth necessary for feature learning: if $LP/N\to 0$, then Bayesian posteriors coincide with those of a kernel method. Regimes where $LP/N\to \lambda >0$, in contrast, correspond to learning with data-dependent deformations of these kernels, and we provide explicit formulas for the resulting features to first order in $1/N$.

We investigate the interface of a glass-forming fluid showing non-Newtonian rheology. By applying shear flow in the interface, we observe that the surface tension depends on the shear rate. Importantly, the standard way of determining surface tension from the pressure anisotropy caused by the interface can give rise to an effective surface tension in the non-Newtonian fluid that mixes bulk and interface properties. We show how the pressure anisotropy can be used to clearly define the bulk and interface regions and extract a genuine shear-rate dependent surface tension. The results have implications for measurement techniques related to the interfacial rheology of complex fluids.

The gravity-driven discharge of granular material through an aperture is a fundamental problem in granular physics and is classically described by empirical laws with different fitting parameters. In this Letter, we disentangle the mass flux into distinct velocity and packing contributions by combining three-dimensional experiments and simulations. We define a dimensionless flux ratio that captures confinement-driven deviations from a free-fall limit, which is recovered when the aperture is large compared to the grain size. For spherical cohesionless grains, the deviations from the free-fall limit are captured by a single exponential correction factor over a characteristic length scale of $\sim 10–15$ grain diameters. This is shown to be the scale over which the packing structure is modified due to the boundary. Building on the $\sqrt{gD}$ exit-velocity scaling, we propose a kinematic framework that explains the universality of granular discharge beyond empirical descriptions.

We present a general framework for deriving entropy production rates in active matter systems driven by non-Gaussian active fluctuations. Employing the probability-flow equivalence technique, we rigorously obtain an entropy production (EP) decomposition formula. We demonstrate that the EP, $\mathrm{\Delta }{s}_{\mathrm{tot}}$, satisfies a detailed fluctuation theorem, ${\rho }_{\mathcal{R}}(\mathrm{\Sigma })/{\rho }_{\mathcal{R}}(-\mathrm{\Sigma })=e^{\mathrm{\Sigma }}$, which holds for the distribution ${\rho }_{\mathcal{R}}(\mathrm{\Sigma })$ defined as the probability of observing a value $\mathrm{\Sigma }$ of the quantity $\mathcal{R}\equiv \mathrm{\Delta }{s}_{\mathrm{tot}}-B_{\mathrm{act}}$, where $B_{\mathrm{act}}$ is a path-dependent random variable associated with active fluctuations. Moreover, an integral fluctuation theorem, $⟨e^{-\mathcal{R}}⟩=1$, and the generalized second law of thermodynamics, $⟨\mathrm{\Delta }{s}_{\mathrm{tot}}⟩\ge ⟨B_{\mathrm{act}}⟩$, follow directly. Our results hold under steady-state conditions and can be straightforwardly extended to arbitrary initial states. In the limiting case where active fluctuations vanish, these theorems reduce to the established results of stochastic thermodynamics. Building on this theoretical foundation, we introduce a deep-learning-based methodology for efficiently computing the EP, utilizing the Lévy score we propose. To illustrate the validity of our approach, we apply it to two representative systems: a Brownian particle in a periodic active bath and an active polymer composed of an active Brownian cross-linker interacting with passive Brownian beads. Our Letter provides a unified framework for analyzing EP in active matter and offers practical computational tools for investigating complex nonequilibrium behavior.

We provide a derivation of quantum theory in which the existence of an energy observable that generates the reversible dynamics follows directly from information-theoretic principles. Our first principle is that every reversible dynamics is implementable through a sequence of fast collisions with an array of identically prepared systems. Combined with four additional principles, known as causality, classical decomposability, purity preservation, and strong symmetry, this collision model pins down the quantum framework, sets up a one-to-one correspondence between energy observables and generators of the dynamics, and provides an information-theoretic derivation of the Mandelstam-Tamm bound on the speed of quantum evolutions.

The KM3NeT experiment has recently observed a neutrino with an energy around 100 PeV, and IceCube has detected five neutrinos with energies above 1 PeV. While there are no known astrophysical sources, exploding primordial black holes could have produced these high-energy neutrinos. For Schwarzschild black holes this interpretation results in tensions between the burst rates inferred from the KM3NeT and IceCube observations, with indirect constraints from the extragalactic gamma-ray background and with the nonobservation of an associated gamma-ray signal at LHAASO. In this Letter we show that if there is a population of primordial black holes charged under a new dark $u(1)$ symmetry which spend most of their time in a quasiextremal state, the neutrino emission at 1 PeV may be more suppressed than at 100 PeV. The burst rates implied by the KM3NeT and IceCube observations and the indirect constraints can then all be consistent at $1\sigma$, and no associated gamma-ray signal was expected at LHAASO. Furthermore, these black holes could constitute all of the observed dark matter in the universe.