When moist air meets a cold surface, it creates a breath figure characterized by numerous small droplets. The central question is how the vapor flux is distributed between the growth of condensed drops and the nucleation of new ones. Here, we investigate the nucleation, growth, and coalescence of droplets on soft substrates consisting of cross-linked polymer networks. The number of droplets initially remains constant, until drops start to coarsen according to a universal law; both phenomena are explained via the formation of a saturated boundary layer. We quantitatively unveil an algebraic sensitivity of the number of droplets on substrate elasticity, which is unexpected since nucleation occurs at a scale where the polymer network resembles a melt. Breath figures thus offer a macroscopic probe of the molecular characteristics of the polymer surface, and suggest a surprisingly low-energy pathway for nucleation.

Dispersal is essential to the plethora of motile microorganisms living in porous environments, yet how it relates to movement patterns and pore space structure remains largely unknown. Here we investigate numerically the long-time dispersal of a run-and-tumble microorganism that remains trapped at solid surfaces and escapes from them by tumbling. We find that dispersal and mean run time are connected by a universal relation, that applies for a variety of porous microstructures and swimming strategies. We explain how this generic dependence originates in the invariance of the mean free path with respect to the movement pattern, and we discuss the optimal strategy that maximizes dispersal. Finally, we extend our approach to microorganisms moving along the surface. Our results provide a general framework to quantify dispersal that works across the vast diversity of movement patterns and porous media.

The eigenstate thermalization hypothesis (ETH) has been highly influential in explaining thermodynamic behavior of closed quantum systems. As of yet, it is unclear whether and how the ETH applies to non-Hermitian systems. Here, we introduce a framework that extends the ETH to non-Hermitian systems, within which expectation values of local operators reproduce statistical and scaling predictions known from Hermitian ETH. We illustrate the validity of the framework on non-Hermitian random-matrix and Sachdev-Ye-Kitaev models. Further, we show numerically how the static ETH predictions become imprinted onto the dynamics of local observables. Finally, we present a prescription for observing both ETH-obeying and ETH-violating regimes in an optical-lattice experiment that implements a disordered interacting Hatano-Nelson model. Our results generalize the celebrated ETH to the non-Hermitian setting, and they show how it affects the system dynamics, and how the salient signatures can be observed in present-day cold-atom experiments.

Recent explorations of the cosmic microwave background and the large-scale structure of the universe have indicated a preference for sizable neutrino self-interactions, much stronger than what the standard model offers. When interpreted in the context of simple particle-physics models with a light, neutrinophilic scalar mediator, some of the hints are already in tension with the combination of terrestrial, astrophysical, and cosmological constraints. We take a novel approach by considering neutrino self-interactions through a mediator with a smooth, continuous spectral density function. We consider Georgi’s unparticle with a mass gap as a concrete example and point out two useful effects for mitigating two leading constraints. (i) The Unparticle is “broadband’—it occupies a wide range of masses which allows it to pass the early universe constraint on effective number of extra neutrinos ($\mathrm{\Delta }{N}_{\mathrm{eff}}$) even if the mass gap lies below the MeV scale. (ii) Scattering involving unparticles is less resonant, which lifts the constraint set by IceCube based on a recent measurement of ultra-high-energy cosmogenic neutrinos. Our analysis shows that an unparticle mediator can open up ample parameter space for strong neutrino self-interactions of interest to cosmology and serves a well-motivated target for upcoming experiments.

The cosmic microwave background (CMB) and baryon acoustic oscillations (BAO) are two of the most robust observations in cosmology. The recent BAO measurements from the DESI collaboration have presented, for the first time, inconsistency between BAO and CMB within the standard cosmological model $\mathrm{\Lambda }\mathrm{CDM}$, indicating a preference for dynamical dark energy over a cosmological constant. We analyze the theoretical implication of the DESI BAO observation for dark energy and gravity employing a nonparametric reconstruction approach for both the dark energy equation of state $w_{\mathrm{DE}}(a)$ and the effective field theory coefficients. We find that the DESI data can rule out quintessence dark energy by indicating a crossing of the phantom divide at $z\lesssim 1$. Furthermore, when analyzed within the broad context of Horndeski gravity which includes general relativity and many known modified gravity theories such as generalized Galileons, $f(R)$, and Brans-Dicke, our result implies that gravity should be nonminimally coupled to explain the observations, establishing the DESI result as the first hint of modified gravity. Based on these insights, we propose the thawing gravity model to explain the nonminimal coupling and phantom crossing indicated by observation, which also fits better to DESI BAO, CMB, and type Ia Supernovae data than $\mathrm{\Lambda }\mathrm{CDM}$.

We measure the noise correlations of two-dimensional (2D) Bose gases after free expansion and use them to characterize the in situ phase coherence across the Berezinskii-Kosterlitz-Thouless (BKT) transition. The noise correlation function features a characteristic spatial oscillatory behavior in the superfluid phase, which gives direct access to the superfluid exponent. This oscillatory behavior vanishes above the BKT critical point, as we demonstrate for both single-layer and decoupled bilayer 2D Bose gases. Our Letter establishes noise interferometry as an important general tool to probe and identify many-body states of quantum gases, extending its application to previously inaccessible correlation properties in multimode systems.

Wavefront shaping techniques allow waves to be focused on a diffraction-limited target deep inside disordered media. To identify the target position, a guidestar is required that typically emits a frequency-shifted signal. Here, we present a noninvasive matrix approach operating at a single frequency only, based on the variation of the field scattered by a nonlinear target illuminated at two different incident powers. The local perturbation induced by the nonlinearity serves as a guide for identifying optimal incident wavefronts. We demonstrate maximal focusing on electronic devices embedded in chaotic microwave cavities and extend our approach to temporal signals. Finally, we exploit the programmability offered by reconfigurable smart surfaces to enhance the intensity delivered to a nonlinear target. Our results pave the way for deep imaging protocols that use any type of nonlinearity as feedback, requiring only the measurement of a monochromatic scattering matrix.

We predict an additional thermal transport pathway across metal-nonmetal interfaces with large electron-phonon nonequilibrium via evanescent radiative heat transfer. In such systems, electron scattering processes vary drastically and can be leveraged to guide heat across interfaces via radiative heat transport without engaging the lattice directly. We employ the formalism of fluctuational electrodynamics to simulate the spectral radiative heat flux across the interface of a metal film and a nonmetal substrate. We find that the radiative conductance can exceed $300\mathrm{MW}{\mathrm{m}}^{-2}{\mathrm{K}}^{-1}$ at an electron temperature of 5000 K for an emitting tungsten film on a hexagonal boron nitride substrate, becoming comparable to its conductive counterpart. This allows for a more holistic approach to the heat flow across interfaces, accounting for electron-phonon nonequilibrium and ultrafast near-field phonon-polariton coupling.

Gauge field theory provides the mathematical and conceptual framework to describe and understand topological singularities such as Weyl points and magnetic monopoles. While singularities associated with vector electromagnetic gauge fields have been well studied, those of higher-form tensor gauge fields, like the four-dimensional (4D) tensor monopoles predicted by string theory, have remained largely theoretical or limited to experimental demonstration in pure synthetic dimensions, thereby not allowing investigations of the associated boundary effects. Here, we present a 4D system with tensor monopoles using engineered acoustic metamaterials. Our momentum space combines three real momentum dimensions and a geometric parameter as the fourth. By varying this fourth momentum, we experimentally reveal two distinct topological surface states in 3D subsystems: Fermi-arc surface states in a gapless subsystem and Dirac-cone surface states in a gapped subsystem. Our work introduces a novel platform for exploring new topological structures associated with tensor gauge field and topological phenomena in higher dimensions.

We have established the method of characterizing the unitary design generated by a symmetric local random circuit. Concretely, we have shown that the necessary and sufficient condition for the circuit asymptotically forming a $t$-design is given by simple integer optimization for general symmetry and locality. By using the result, we explicitly give the maximal order of unitary design under the ${\mathbb{Z}}_2$, U(1), and SU(2) symmetries for general locality. This work reveals the relation between the fundamental notions of symmetry and locality in terms of randomness.

We introduce a quantum extension of dynamic programming, a fundamental computational method that efficiently solves recursive problems using memory. Our innovation lies in showing how to coherently generate recursion step unitaries by using memorized intermediate quantum states. Quantum dynamic programming achieves an exponential reduction in circuit depth for a broad class of fixed-point quantum recursions, though this comes at the cost of increased circuit width. Interestingly, the trade-off becomes more favorable when the initial state is pure. By hybridizing our approach with a conventional memoryless one, we can flexibly balance circuit depth and width to optimize performance on quantum devices with fixed hardware constraints. Finally, we showcase applications of quantum dynamic programming to several quantum recursions, including a variant of Grover’s search, quantum imaginary-time evolution, and a new protocol for obliviously preparing a quantum state in its Schmidt basis.

Low-energy dynamics of QCD can be described by pion degrees of freedom in terms of the chiral perturbation theory. A chiral soliton lattice, an array of solitons, is the ground state due to the chiral anomaly in the presence of a magnetic field larger than a certain critical value at finite density. Here, we show in a model-independent and fully analytic manner (at the leading order of the chiral perturbation theory) that the chiral soliton lattice phase transits to a “domain-wall skyrmion phase” when the chemical potential is larger than the critical value ${\mu }_{\mathrm{c}}=16\pi f_{\pi }^2/3m_{\pi }\sim 1.03\mathrm{GeV}$ with the pion’s decay constant $f_{\pi }$ and mass $m_{\pi }$, which can be regarded as the nuclear saturation density. There spontaneously appear stable two-dimensional skyrmions or lumps on a soliton surface, which can be viewed as three-dimensional skyrmions carrying even baryon numbers from the bulk. They behave as superconducting rings with persistent currents due to a charged pion condensation. This phase is in scope of future heavy-ion collider experiments.

Nuclear charge radii of neutron-rich ${}^{47–49}\mathrm{Sc}$ isotopes were measured using collinear laser spectroscopy at CERN-ISOLDE. The new data reveal that the charge radii of scandium isotopes exhibit a distinct trend between $N=20$ and $N=28$, with ${}^{41}\mathrm{Sc}$ and ${}^{49}\mathrm{Sc}$ isotopes having similar values, mirroring the closeness of the charge radii of ${}^{40}\mathrm{Ca}$ and ${}^{48}\mathrm{Ca}$. Theoretical models that successfully interpret the radii of calcium isotopes could not account for the observed behavior in scandium radii, in particular the reduced odd-even staggering. Remarkably, the inclusion of the new ${}^{49}\mathrm{Sc}$ radius data has unveiled a similar trend in the charge radii of $N=28$ isotones and $Z=20$ isotopes when adding the protons atop the ${}^{48}\mathrm{Ca}$ core and the neutrons atop the ${}^{40}\mathrm{Ca}$ core, respectively. We demonstrate that this trend is consistent with the prediction of the seniority model.

Thermodynamics of degenerate Fermi gases has been extensively studied through various aspects such as Pauli blocking effects, collective modes, BCS superfluidity, and more. Despite this, multicomponent fermions with imbalanced spin configurations remain largely unexplored, particularly beyond the two-component scenario. In this Letter, we generalize the thermodynamic study of $\mathrm{SU}(N)$ fermions to spin-imbalanced configurations based on density fluctuations. Theoretically, we provide closed-form expressions of density fluctuation across all temperature ranges for general spin population setups. Experimentally, after calibrating the measurements with deeply degenerate ${}^{173}\mathrm{Yb}$ Fermi gases under spin-balanced configurations ($N\le 6$), we examine the density fluctuations in spin-imbalanced systems. Specifically, we investigate two-species and four-species configurations to validate our theoretical predictions. Our analysis indicates that interaction enhancement effects can be significant even in highly spin-imbalanced systems. Finally, as an application, we use this approach to examine the decoherence process. Our Letter provides a deeper understanding of the thermodynamic features of spin-imbalanced multicomponent Fermi gases and opens new avenues for exploring complex quantum many-body systems.

We investigate the minimal requirements that induce a nonreciprocal response to temperature differences in a mesoscopic electronic conductor. We identify two distinct mechanisms involved in electron-electron interactions, namely inelastic scattering and screening, that locally affect the internal properties of the device, leading to thermal and thermoelectric rectification effects in the absence of inversion symmetry. We propose resonant tunneling samples to efficiently exploit these effects, and find configurations acting as bipolar thermoelectric diodes whose current flows in the same direction irrespective of the sign of the temperature difference, a case of antireciprocity.

The classical sandpile model for self-organized criticality is analyzed with deterministic perturbations. This allows us to explore underlying long-range correlations in the critical attractor and quantify these as the fractal dimension of excitable sites and the fractal dimension of avalanche termination sites. The fractal of highly excitable sites, characterized by a dimension of 1.3, is associated with the avalanches responsible for most of the relaxations in the system. Furthermore, the fractal dimension of these highly excitable sites suggests a scaling exponent for avalanche sizes of 1.26, consistent with earlier literature.

The failure of interdependent networks, as well as similar avalanche phenomena, is driven by cascading failures. At the critical point, the cascade begins as a critical branching process, where each failing node (element) triggers, on average, the failure of one other node. As nodes continue to fail, the network becomes increasingly fragile, and the branching factor grows. If the failure process does not reach extinction during its critical phase, the network undergoes an abrupt collapse. Here, we implement the analogy between this dynamic and birth-death processes to derive new analytical results and significantly optimize numerical calculations. Using this approach, we analyze three key aspects of the dynamics: the probability of collapse, the duration of avalanches, and the length of the cascading plateau phase preceding a collapse. This analysis quantifies how the system size and the intensity of the initial triggering event influence these characteristics.

We study the deformation of a liquid interface with arbitrary principal curvatures by a flat circular sheet. Working first at small slopes, we determine the shape of the sheet analytically in the membrane limit, where the sheet is inextensible yet free to bend and compress. We find that the sheet takes a cylindrical shape on interfaces with negative Gaussian curvature. On interfaces with positive Gaussian curvature, an inner region still adopts a cylindrical shape while the outer region is under azimuthal compression. Numerical energy minimization confirms our predictions and shows that this behavior holds for finite slopes. Experiments on a thin polystyrene film at an anisotropic air-water interface show consistent behaviors.