High-resolution measurements of the positronium formation cross sections for positron energies from threshold to 10 eV are presented for aniline (${\mathrm{C}}_6{\mathrm{H}}_5{\mathrm{NH}}_2$), pyridine (${\mathrm{C}}_5{\mathrm{H}}_5\mathrm{N}$), and cyclopentane (${\mathrm{C}}_5{\mathrm{H}}_{10}$). The data reveal that the measured energy dependence of the cross sections on the excess energy in the near-threshold region (1–2 eV) is nearly identical to that of the corresponding photoionization cross sections. This similarity occurs despite the difference between the basic threshold laws for processes without and with a Coulomb interaction between the final-state particles. It is proposed here that the near-threshold behavior of these two different ionization processes is governed by the vibrational dynamics of the final-state cation. This is supported by comparison of the data with the calculated spectrum of vibronic intensities for the pyridine cation [Trofimov et al., J. Chem. Phys. 153, 164307 (2020)].

Two-photon double ionization is a paradigmatic example of how electron correlation manifests. In molecular targets, its coupling with the slower nuclear motion introduces an additional complication and induces electron-electron-nuclei correlations. Experimentally, momentum-coincident measurements can provide a complete kinematical image of the molecular full Coulomb breakup. Previous theoretical studies have described this process by ignoring nuclear motion and the subsequent Coulomb explosion of the dication. Here we show, by means of a full-dimensional treatment of two-photon double ionization of the ${\mathrm{H}}_2$ molecule, that nuclear motion plays a decisive role even for pulses as short as 1.5 fs, a time during which the nuclei are not expected to move significantly. We find strong correlations between nuclear and electronic degrees of freedom, giving access to different electronic processes as a function of nuclear kinetic energy. In particular, we observe unexpectedly strong back-to-back asymmetry in the photoelectron angular distributions, as well as novel interferences resulting from the coherent contributions from two-photon sequential absorption paths via different molecular cationic states.

Rydberg alkaline earth atoms are promising tools for quantum simulation and metrology. When one of the two valence electrons is promoted to long-lived circular states, the second valence electron can be optically manipulated without significant autoionization. We harness this feature to demonstrate laser slowing of a thermal atomic beam of circular strontium atoms. By driving the main ion core 422 nm wavelength resonance, we observe a velocity reduction of $50\mathrm{m}/\mathrm{s}$ without significant autoionization. We also show that a superposition of circular states undergoes very weak decoherence during the cooling process, up to the scattering of more than 1000 photons. This robustness opens new perspectives for quantum simulations over long timescales with circular atoms, while simultaneously cooling their motional state. It makes it possible to mitigate the harmful effects of unavoidable heating due to spin-motion coupling during a quantum simulation.

A universal power-law scaling $\overline{z}\propto E^{0.4}$ in the correlation between the average ion charge state $\overline{z}$ and kinetic energy $E$ in expanding laser-driven tin plasmas is identified. Universality here refers to an insensitivity to all experimental conditions: target geometry, expansion direction, laser wavelength, and power density. The power law is accurately captured in an analytical consideration of the dependence of the charge state on temperature and the subsequent transfer of internal to kinetic energy in the expansion. These analytical steps are individually, and collectively, validated by a two-dimensional radiation-hydrodynamic simulation of an expanding laser-driven plasma. This power-law behavior is expected to hold also for dense plasma containing heavier, complex ions such as those relevant to current and future laser-driven plasma light sources.

The recent discovery of high-temperature superconductivity in ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_7$ offers a fresh platform for exploring unconventional pairing mechanisms. Starting with the basic argument that the electrons in $d_{z^2}$ orbitals nearly form local moments, we examine the effect of the Hubbard interaction $U$ on the binding strength of Cooper pairs based on a single-orbital bilayer model with intralayer hopping $t_{\parallel }$ and interlayer superexchange $J_{\perp }$. By extensive density matrix renormalization group calculations, we observe a remarkable enhancement in binding energy as much as 10–20 times larger with $U/t_{\parallel }$ increasing from 0 to 12 at $J_{\perp }/t_{\parallel }\sim 1$. We demonstrate that such a substantial enhancement stems from a kinetic-energy-driven mechanism. Specifically, a ${\mathbb{Z}}_2$ Berry phase will emerge at large $U$ due to the Hilbert space restriction (Mottness), which strongly suppresses the mobility of single particle propagation as compared to $U=0$. However, the kinetic energy of the electrons (holes) can be greatly restored by forming an interlayer spin-singlet pairing, which naturally results in a superconducting state even for relatively small $J_{\perp }$. An effective hard-core bosonic model is further proposed to estimate the superconducting transition temperature at the mean-field level.

We demonstrate that slow growth of the number entropy following a quench from a local product state is consistent with many-body localization. To do this, we construct a novel random circuit $\ell$-bit model with exponentially localized $\ell$-bits and exponentially decaying interactions between them. We observe an ultraslow growth of the number entropy starting from a Néel state, saturating at a value that grows with system size. This suggests that the observation of such growth in microscopic models is not sufficient to rule out many-body localization.

It has long been suspected that magnetism could play a vital role in the phase stability of multicomponent high-entropy alloys. However, the nature of the magnetic order, if any, has remained elusive. Here, by using elastic and inelastic neutron scattering, we demonstrate evidence of antiferromagnetic order below $\sim 80\mathrm{K}$ and strong spin fluctuations persisting to room temperature in a single-phase face-centered cubic (fcc) CrMnFeCoNi high-entropy alloy. Despite the chemical complexity, the magnetic structure in CrMnFeCoNi can be described as $\gamma$-Mn-like, with the magnetic moments confined in alternating (001) planes and pointing toward the $⟨111⟩$ direction. Combined with first-principles calculation results, it is shown that the antiferromagnetic order and spin fluctuations help stabilized the fcc phase in CrMnFeCoNi high-entropy alloy.

Sliding ferroelectricity is a unique type of polarity recently observed in van der Waals bilayers with a suitable stacking. However, electric-field control of sliding ferroelectricity is hard and could induce large coercive electric fields and serious leakage currents that corrode the ferroelectricity and electronic properties, which are essential for modern two-dimensional electronics and optoelectronics. Here, we proposed laser-pulse deterministic control of sliding polarization in bilayer hexagonal boron nitride by first principles and molecular dynamics simulation with machine-learned force fields. The laser pulses excite shear modes that exhibit certain directional movements of lateral sliding between bilayers. The vibration of excited modes under laser pulses is predicted to overcome the energy barrier and achieve the switching of sliding polarization. Furthermore, it is found that three possible sliding transitions—between AB (BA) and BA (AB) stacking—can lead to the occurrence of dynamical magnetic fields along three different directions. Remarkably, the magnetic fields are generated by the simple linear motion of nonmagnetic species, without any need for more exotic (circular, spiral) pathways. Such predictions of deterministic control of sliding polarization and multistates of dynamical magnetic field thus expand the potential applications of sliding ferroelectricity in memory and electronic devices.

Dynamically changing interpersonal relationships lie at the core of the emergence of in-group structures, such as polarity or conflict. We explore these dynamics in a simple continuous dynamical model obtained by generalizing a previously proposed model based on Heider’s balance theory from social psychology. Previous findings include a rigorous proof of the emergence of in-group harmony or bipolar conflict (global minima) and the identification of local minima called jammed states, along with their corresponding energy spectrum in terms of structural complexity. However, some unrealistic scenarios constrain our capacity to contextualize and directly apply these results to real-world social behaviors. To address these challenges, we first introduce a unified dynamical model and find that group size can be critical to the onset of in-group bipolar conflict. Using random matrix statistics, we then characterize the pathways leading to jammed states, which have previously been discussed only in stochastic models. Unexpectedly, we also show that perturbing our dynamical model can increase the chances of getting trapped in jammed states, giving rise to a novel notion called the noise-induced jammed state. We conclude this Letter by discussing possible real-world implications as well as potential contributions to the existing literature in relevant fields such as anthropology.

In this Letter, we unveil an eccentric superradiance phenomenon in molecular aggregates coupled to surface plasmon polaritons. Through the quantization of electromagnetic fields in media, we demonstrate that superradiance can be significantly enhanced by polaritons and its behavior distinguishably surpasses the Dicke’s $N$ scaling law. To understand the mechanism of this anomalous phenomenon, we derive an analytical expression of the superradiance rate, which is general for molecular aggregates in arbitrary dispersive and absorbing media. Furthermore, we demonstrate the importance of intermolecular distance for this extraordinary superradiance.

The Vicsek simulation model of flocking together with its theoretical treatment by Toner and Tu in 1995 were two foundational cornerstones of active matter physics. However, despite the field’s tremendous progress, the actual universality class (UC) governing the scaling behavior of Viscek’s “flocking” phase remains elusive. Here, we use nonperturbative, functional renormalization group methods to analyze, numerically and analytically, a simplified version of the Toner-Tu model, and uncover a novel UC with scaling exponents that agree remarkably well with the values obtained in a recent simulation study by Mahault et al. [Phys. Rev. Lett. 123, 218001 (2019)], in both two and three spatial dimensions. We therefore believe that there is strong evidence that the UC uncovered here describes Vicsek’s flocking phase.

Optically interfaced molecular spins are a promising platform for quantum sensing and imaging. Key for such applications is optically detecting coherent spin manipulation at room temperature. Here, using the photoexcited triplet state of organic chromophores (pentacene doped in $p$-terphenyl), we optically detect coherent spin manipulation with photoluminescence contrasts exceeding 15% at room temperature, both in a molecular crystal and thin film. We further demonstrate how multifrequency spin control could enhance such systems. These results open opportunities for room-temperature quantum sensors that capitalize on the versatility of synthetic chemistry.

Current bounds on the neutrino Majorana mass are affected by significant uncertainties in the nuclear calculations for neutrinoless double-beta decay. A key issue for a data-driven improvement of the nuclear theory is the actual value of the axial coupling constant $g_{\mathrm{A}}$, which can be investigated through forbidden $\beta$ decays. We present the first measurement of the 4th-forbidden $\beta$ decay of ${}^{115}\mathrm{In}$ with a cryogenic calorimeter based on indium iodide. Exploiting the enhanced spectrum-shape method for the first time to this isotope, our study accurately determines simultaneously spectral shape, $g_{\mathrm{A}}$, and half-life. The interacting shell model, which best fits our data, indicates a half-life for this decay at $T_{1/2}=(5.26\pm 0.06)\times {10}^{14}\mathrm{yr}$.

We present a generalized dynamical mean field theory for studying the effects of non-Gaussian quenched noise in a general set of dynamical systems. We apply the framework to the generalized Lotka-Volterra equations, a central model in theoretical ecology, where species interactions are fixed over time and heterogeneous. Our results show that the new mean field equations have solutions that depend on all cumulants of the distribution of species interactions. We obtain an analytic solution when the interaction couplings are $\alpha$-stable distributed and find a relationship between the abundance distribution of species and the statistics of microscopic interactions. In the case of sparse interactions, which we investigate analytically, we establish a simple relationship between the distribution of interactions and the one of population densities.

We introduce the domain wall color code, a new variant of the quantum error-correcting color code that exhibits exceptionally high code-capacity error thresholds for qubits subject to biased noise. In the infinite bias regime, a two-dimensional color code decouples into a series of repetition codes, resulting in an error-correcting threshold of 50%. Interestingly, at finite bias, our color code demonstrates thresholds identical to those of the noise-tailored XZZX surface code for all single-qubit Pauli noise channels. The design principle of the code is that it introduces domain walls which permute the code’s excitations upon domain crossing. For practical implementation, we supplement the domain wall code with a scalable restriction decoder based on a matching algorithm. The proposed code is identified as a comparably resource-efficient quantum error-correcting code highly suitable for realistic noise.

It has been recently proposed that the boosted dark matter (BDM) by supernova neutrinos ($\mathrm{SN}\nu$) from SN1987a or from the next Galactic supernova (SN) can serve as a novel component to probe nonvanishing interaction between dark matter (DM) and the standard model leptons [Y.-H. Lin et al., Phys. Rev. Lett. 130, 111002 (2023) and Y.-H. Lin et al., Phys. Rev. D 108, 083013 (2023)]. In this Letter, we extend this concept and evaluate the present-day diffuse flux of $\mathrm{SN}\nu$ BDM originated from all galaxies at higher redshifts. We show that by considering this diffuse BDM (DBDM) component, the best sensitivity on the product of the energy-independent DM-$\nu$ and DM-electron cross sections, $\sqrt{{\sigma }_{\chi \nu }{\sigma }_{\chi e}}\simeq \mathcal{O}({10}^{-37}){\mathrm{cm}}^2$ for sub-MeV DM, can be obtained with large-size neutrino experiments such as Super-Kamiokande or Hyper-Kamiokande, surpassing the estimated $\mathrm{SN}\nu$ BDM bound from SN1987a. We also examine the impact due to the presence of DM spikes around the supermassive black holes in galaxies on $\mathrm{SN}\nu$ BDM and DBDM. Our results suggest that both the DBDM and the $\mathrm{SN}\nu$ BDM probes are robust to the uncertain properties of DM spikes, unless the next Galactic SN happens to occur at a location extremely close to or right behind the Galactic Center along the SN line of sight.