In confined hadronic matter, the spontaneous breaking and restoration of chiral symmetry can be described by considering nucleons, $N_{+}(939)$, and excited states of opposite parity, $N_{-}(1535)$. In a cold, dense hadronic phase where chiral symmetry remains spontaneously broken, direct Urca decay processes involving the $N_{-}$ are possible, e.g., $N_{-}\to N_{+}+e^{-}+{\overline{\nu }}_e$. We show that at low temperature and moderate densities, because the $N_{-}$ are much heavier than the $N_{+}$, such cooling dominates over standard $N_{+}$ direct Urca processes. This provides a strong astrophysical signature of the pattern of chiral symmetry restoration in neutron stars.

When a drop contacts and absorbs in a thin porous surface, it can wick radially outward. This phenomenon is exploited in cooling textiles, but also complicates forensic stain analysis. The distance that the liquid spreads and the time it takes to evaporate are coupled, yet the consequence of this coupling on the wicking dynamics is not well understood. Here we measure and model how evaporation can reverse the direction of the liquid front so that the wetted patch shrinks after reaching a maximum diameter. We show that both this maximum diameter and the time to fully evaporate can be predicted with a single dimensionless parameter based on the substrate and liquid properties. Yet regardless of the system properties, we uncover a universal dynamic in which drops expand for approximately $1/4$ of their lifetime and shrink for the rest. Counterintuitively, we find that neither the evaporative cooling nor the stain area scales linearly with the initial droplet volume.

We report on voltage-tuned phase transitions in arrays of hybrid semiconductor-superconductor islands arranged in a square lattice. A double-layer electrostatic gate geometry enables independent tuning of interisland coupling and proximity-induced superconductivity. This design enables access to the superconductor-insulator, superconductor-metal, and metal-insulator transitions in a single device, revealing critical points and emergent intermediate phases. We find that the superconductor-insulator transition is interrupted by an anomalous metallic phase with saturating low-temperature resistivity. Across gate voltages, this regime extends over 3 orders of magnitude in resistivity and can be continuously tuned into the conventional metallic phase. The signature of the anomalous metallic phase is suppressed by magnetic frustration.

We present a quantum response approach to momentum-space gravity in dissipative multiband systems, which dresses both the quantum geometry—through an interband Weyl transformation—and the equations of motion. In addition to clarifying the roles of the contorsion and symplectic terms, we introduce the three-state quantum geometric tensor as a necessary element in the geometric classification of nonlinear responses and discuss the significance of the emergent terms from a gravitational point of view. We also identify a dual quantum geometric drag force in momentum space that provides an entropic source term for the multiband matrix of Einstein field equations.

Electron microscopy uses energy-dispersive x-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS) for elemental analysis. EDS and EELS energy resolutions are commonly between 30 and 100 eV or 0.01 and 1 eV, respectively. Large solid angle EDS detector technology has increased collection efficiency to enable precision spectroscopy via averaging of 0.02–0.1 eV. This improved precision gives access to chemical shifts; examples are shown in compounds of Al, Ti, and W. EDS can now detect chemical information in a complementary parameter space (accelerating voltage, thickness, atomic number) to that covered by EELS.

Cell-to-cell heterogeneity in transcription, or transcriptional noise, is important in cellular development and in disease. The molecular mechanisms driving it are, however, elusive and ill-understood. Here, we use computer simulations to explore the role of 3D chromatin structure in driving transcriptional noise. We study a simple polymer model where proteins—modeling complexes of transcription factors and polymerases—bind multivalently to transcription units—modeling regulatory elements such as promoters and enhancers. We also include cohesinlike factors that extrude chromatin loops that are important for the physiological folding of chromosomes. We find that transcription factor binding creates spatiotemporal patterning and a highly variable correlation time in transcriptional dynamics, which is linked to the cell-to-cell variation in gene expression. Loop extrusion also contributes to noise, as the stochastic nature of this process leads to different networks of cohesin loops in different cells in our model. Our results could be tested with single-cell experiments and provide a pathway to understanding the principles underlying transcriptional plasticity in vivo.

Efficient generation of large-scale multipartite entangled states is a critical but challenging task in quantum information processing. Although generation of multipartite entanglement within a small set of individual qubits has been demonstrated, further scale-up in system size requires the connection of smaller entangled states into a larger state in a scalable and modular manner. Here, we achieve this goal by implementing memory-enhanced fusion of two multipartite entangled states via photonic interconnects. Through asynchronous preparation of two tripartite $W$-state entanglements in two spatially separated modules of atomic quantum memories and on-demand fusion via single-photon interference, we demonstrate the creation of a four-partite $W$-state entanglement shared by two remote quantum memory modules in a heralded way. We also demonstrate memory-enhanced scaling in efficiencies in the entanglement fusion. The demonstrated scalable generation and fusion of multipartite entangled states pave the way toward realization of large-scale distributed quantum information processing in the future.

An optical flux lattice is a set of light beams that couple different internal states of an atom, thereby producing topological energy bands. Here we present a configuration in which the atoms exhibit a dark state, i.e., an internal state that is not coupled to the light. At large light intensity, the low-energy dynamics is restricted to the dark state, leading to an effective continuum model with a Landau-level-like structure. This structure is dramatically different from that of usual topological optical lattices, which lead to discrete models in the tight-binding limit. For well-chosen atomic species, the proposed system is essentially immune to heating due to photon scattering, making it a highly promising way to emulate the integer or fractional quantum Hall effect.

The generation of intense, femtosecond-scale x-ray pulses is crucial for probing matter under extreme temporal and field conditions. Current chirped-pulse amplification (CPA) techniques in free-electron lasers (FELs), however, face efficiency limitations in the soft x-ray regime due to the inherent constraints of conventional optical compressors. To address this challenge, we propose a high-efficiency plasma-based compressor utilizing highly ionized noble gas plasma. Exploiting strong refractive index dispersion near ionic resonances, this scheme achieves over 70% transmission efficiency around 5.2 nm and is extendable to other highly charged ions for operation across the soft x-ray to vacuum ultraviolet range. Simulations demonstrate that a 25 fs FEL pulse can be compressed to 1.4 fs with peak power boosted to over 100 GW, while maintaining high-energy throughput. This transformative approach bridges the soft x-ray CPA gap and opens a scalable path toward compact, high-brightness attosecond FEL sources.

We investigate the superconducting instabilities induced by altermagnetic fluctuations. Because of the nontrivial sublattice structure of the altermagnetic order, shorter-range and longer-range fluctuations favor qualitatively different types of pairing states. Specifically, while the latter stabilize a standard spin-triplet $p$-wave state, just like ferromagnetic fluctuations, the former leads to intra-unit-cell pairing, in which the Cooper pairs are formed by electrons from different sublattices. The symmetry of the intra-unit-cell gap function can be not only $p$-wave, but also spin-singlet $s$-wave and $d$-wave, depending on the shape of the Fermi surface. We also show that coexistence with altermagnetic order promotes intrinsic nontrivial topology, such as protected Bogoliubov Fermi surfaces and higher-order topological superconductivity. Our Letter establishes the key role played by sublattice degrees of freedom in altermagnetic-fluctuation mediated interactions.

We study the emergence of altermagnetism from repulsive interactions for electrons on the Lieb lattice as a model of quasi-2D oxychalcogenides with the so-called “$\mathrm{anti}\text{−}{\mathrm{CuO}}_2$” lattice structure. A comprehensive study of the Lieb lattice Hubbard model, using unrestricted Hartree-Fock and exact diagonalization techniques, establishes the presence of a spin-$\frac{1}{2}$ altermagnetic Mott insulating ground state for average electron densities of 2 and 4 per unit cell. Both phases show the characteristic spin splitting in the electron bands as well as in the magnon bands, as indicated by solutions of an effective spin-$\frac{1}{2}$ Heisenberg model that we construct. We also provide evidence for altermagnetic metal formation in the electron- and hole-doped Mott state, giving rise to Fermi surfaces with $d_{x^2-y^2}$-wave spin splitting and quasi-one-dimensional characteristics.

Spinons are elementary excitations at the core of frustrated quantum magnets. Although it is well established that a pair of spinons can emerge from a magnon via deconfinement, controlled manipulation of individual spinons and direct observation of their deconfinement remain elusive. We propose an artificial gauge field scenario that enables the engineering of specific excited states in quantum spin models. This generates spatially localized individual spinons with high controllability. By applying time-dependent gauge fields, we realize adiabatic braiding of these spinons, as well as their dynamical evolution in a controllable manner. These results not only provide the first direct visualization of individual spinons localized in the bulk, but also point to new possibilities to simulate their confinement process. Finally, we demonstrate the feasibility of our scenario in Rydberg atoms, which suggests an experimentally viable direction-gauge-field engineering of correlated phenomena in excited states.

The use of orbital torques to efficiently modulate magnetization is currently a central topic in orbitronics. In this Letter, we report the discovery of an unexpectedly large dampinglike torque efficiency per unit electric field in metallic $\mathrm{PtCo}/\mathrm{Cu}$ heterostructures, with its maximum value being 2 (1) orders of magnitude higher than that in typical heavy-metal Ta (Pt) systems. Current-induced magnetization reversal experiments confirm the enhanced dampinglike torque efficiency, which increases significantly with the thickness of the Cu layer. We attribute this ultraefficient orbital torque to the interfacial vorticity of the drift velocity of conduction electrons, arising from the substantial resistivity difference between the Cu and PtCo layers. The remarkable dampinglike torque efficiency demonstrated in our Letter highlights the potential of interfacial vorticity in spin orbitronics, suggesting a promising new direction for future research in the field.

Recent advancements highlight the critical need for ferroelectric (FE) materials compatible with silicon, particularly pure silicon phases exhibiting FE behavior above room temperature that can be readily integrated onto silicon substrates. Here, we systematically predict potential FE silicon films using first-principles structure searching. Furthermore, we develop an advanced machine learning model that simultaneously predicts interatomic potentials and Born effective charges to investigate their FE behavior. In particular, we discover a low-energy FE silicon film merely $1\mathrm{meV}/\mathrm{atom}$ above its antiferroelectric (AFE) ground state. Both phases are confirmed to be dynamically and mechanically stable semiconductors with indirect band gaps of approximately 1.3 eV. Although the ground state exhibits AFE ordering, our simulations with the machine learning model remarkably reveal a robust FE hysteresis loop above room temperature, characterized by a low coercive field of about $0.05\mathrm{V}/\AA$. An effective Hamiltonian model analysis indicates that this anomalous FE behavior arises from weak AFE coupling between the top and bottom surfaces of the silicon film. These findings of a switchable FE state in pure silicon phases suggest their potential use in memory devices, sensors, and energy converters.

Engineering phases of matter in cavities requires effective light-matter coupling strengths that are on the same order of magnitude as the bare system energetics, coined the ultrastrong coupling regime. For models of itinerant electron systems, which do not have discrete energy levels, a clear definition of this regime has been lacking to date. Here, we argue that a change of the electronic mass exceeding 10% of its bare value may serve as such a definition. We propose a quantitative computational scheme for obtaining the electronic mass in relation to its bare vacuum value and show that coupling to surface polariton modes can induce such mass changes. Our results have important implications for cavity design principles that enable the engineering of electronic properties with quantum light.

We investigate phase transitions in the nonequilibrium dynamics of power-law interacting spin-$1/2$ bilayer XXZ models, which have recently been shown to allow generation of entanglement in the form of two-mode squeezing. We find a transition between a collective phase characterized by Heisenberg limited squeezing and a partially collective phase with scalable squeezing. We identify universal scaling of the squeezing dynamics in terms of system parameters and a divergent timescale, establishing these as distinct dynamical phases within the framework of nonequilibrium critical phenomena. Our Letter demonstrates a novel dynamical phase transition with potential applications in quantum sensing and quantum simulation in cold-atomic, molecular, or Rydberg platforms.

Counting ground state degeneracy of a $k$-local Hamiltonian is important in many fields of physics. Its complexity class is harder than that of finding the ground state of a $k$-local Hamiltonian. Very few methods can efficiently count the degeneracy of ground state while many are known for finding the ground state. This Letter proposes an algorithm for mapping the problem of counting ground state degeneracy into one for finding a special ground state of a $k$-local super Hamiltonian in an enlarged system with twice as many qubits or spins. We show that all traditional methods, designed for finding the ground state by evolution under a function of a Hamiltonian, can be employed to find the special ground state of the super Hamiltonian from a well-designed initial state and thus can be used to count the ground degeneracy. We combine our algorithm with the power method, the Lanczos method, and the quantum imaginary time evolution method for selective examples to illustrate the detection of phase boundaries, competition between frustration and quantum fluctuation, and potential implementation with quantum circuits.