Materials once suffered at high-pressure and high-temperature (HPHT) conditions often exhibit exotic phenomena that defy conventional wisdom. The behaviors of sulfur dioxide (${\mathrm{SO}}_2$), one of the archetypal simple molecules, at HPHT conditions have attracted a great deal of attention due to its relevance to the S cycle between deep Earth and the atmosphere. Here we report the discovery of an unexpected disproportionation of ${\mathrm{SO}}_2$ via bond breaking into elemental S and sulfur trioxide (${\mathrm{SO}}_3$) at HPHT conditions through a jointly experimental and theoretical study. Measured x-ray diffraction and Raman spectroscopy data allow us to solve unambiguously the crystal structure (space group $R\overline{3}c$) of the resultant ${\mathrm{SO}}_3$ phase that shows an extended framework structure formed by vertex-sharing octahedra ${\mathrm{SO}}_6$. Our findings lead to a significant extension of the phase diagram of ${\mathrm{SO}}_2$ and suggest that ${\mathrm{SO}}_2$, despite its abundance in Earth’s atmosphere and ubiquity in other giant planets, is not a stable compound at HPHT conditions relevant to planetary interiors, providing important implications for elucidating the S chemistry in deep Earth and other giant planets.

Understanding complex materials at different length scales requires reliably accounting for van der Waals (vdW) interactions, which stem from long-range electronic correlations. While the important role of many-body vdW interactions has been extensively documented for the stability of materials, much less is known about the coupling between vdW interactions and atomic forces. Here we analyze the Hessian force response matrix for a single and two vdW-coupled atomic chains to show that a many-body description of vdW interactions yields atomic force response magnitudes that exceed the expected pairwise decay by 3–5 orders of magnitude for a wide range of separations between perturbed and observed atoms. Similar findings are confirmed for carbon nanotubes, graphene, and delamination of graphene from a silicon substrate previously studied experimentally. This colossal force enhancement suggests implications for phonon spectra, free energies, interfacial adhesion, and collective dynamics in materials with many interacting atoms.

We investigate the twist-angle and gate dependence of the proximity exchange coupling in twisted graphene on monolayer ${\mathrm{Cr}}_2{\mathrm{Ge}}_2{\mathrm{Te}}_6$ from first principles. The proximitized Dirac band dispersions of graphene are fitted to a model Hamiltonian, yielding effective sublattice-resolved proximity-induced exchange parameters (${\lambda }_{\mathrm{ex}}^A$ and ${\lambda }_{\mathrm{ex}}^B$) for a series of twist angles between 0° and 30°. For aligned layers (0° twist angle), the exchange coupling of graphene is the same on both sublattices, ${\lambda }_{\mathrm{ex}}^A\approx {\lambda }_{\mathrm{ex}}^B\approx 4\mathrm{meV}$, while the coupling is reversed at 30° (with ${\lambda }_{\mathrm{ex}}^A\approx {\lambda }_{\mathrm{ex}}^B\approx -4\mathrm{meV}$). Remarkably, at 19.1° the induced exchange coupling becomes antiferromagnetic: ${\lambda }_{\mathrm{ex}}^A<0$, ${\lambda }_{\mathrm{ex}}^B>0$. Further tuning is provided by a transverse electric field and the interlayer distance. The predicted proximity magnetization reversal and emergence of an antiferromagnetic Dirac dispersion make twisted $\text{graphene}/{\mathrm{Cr}}_2{\mathrm{Ge}}_2{\mathrm{Te}}_6$ bilayers a versatile platform for realizing topological phases and for spintronics applications.

In this Letter, we illustrate how polarized neutron scattering can be used to isolate the spin-spin correlations of modes forming flat bands in a frustrated magnetic system hosting a classical spin liquid phase. In particular, we explain why the nearest-neighbor spin ice model, whose interaction matrix has two flat bands, produces a dispersionless (i.e., “flat”) response in the non-spin-flip (NSF) polarized neutron scattering channel and demonstrate that NSF scattering is a highly sensitive probe of correlations induced by weak perturbations that lift the flat band degeneracy. We use this to explain the experimentally measured dispersive (i.e., nonflat) NSF channel of the dipolar spin ice compound ${\mathrm{Ho}}_2{\mathrm{Ti}}_2{\mathrm{O}}_7$.

Active matter broadly covers the dynamics of self-propelled particles. While the onset of collective behavior in homogenous active systems is relatively well understood, the effect of inhomogeneities such as obstacles and traps lacks overall clarity. Here, we study how interacting, self-propelled particles become trapped and released from a trap. We have found that captured particles aggregate into an orbiting condensate with a crystalline structure. As more particles are added, the trapped condensates escape as a whole. Our results shed light on the effects of confinement and quenched disorder in active matter.

The present Letter shows that the formation of ozone in ternary collisions $\mathrm{O}+{\mathrm{O}}_2+M$—the primary mechanism of ozone formation in the stratosphere—at temperatures below 200 K (for $M=\mathrm{Ar}$) proceeds through a formation of a temporary complex $M{\mathrm{O}}_2$, while at temperatures above $\sim 700\mathrm{K}$, the reaction proceeds mainly through a formation of long-lived vibrational resonances of ${\mathrm{O}}_3^{*}$. At intermediate temperatures 200–700 K, the process cannot be viewed as a two-step mechanism, often used to simplify and approximate collisions of three atoms or molecules. The developed theoretical approach is applied to the reaction $\mathrm{O}+{\mathrm{O}}_2+\mathrm{Ar}$ because of extensive experimental data available. The rate coefficients for the formation of ${\mathrm{O}}_3$ in ternary collisions $\mathrm{O}+{\mathrm{O}}_2+\mathrm{Ar}$ without using two-step approximations were computed for the first time as a function of collision energy. Thermally averaged coefficients were derived for temperatures 5–900 K. It is found that the majority of ${\mathrm{O}}_3$ molecules formed initially are weakly bound. Accounting for the process of vibrational quenching of the nascent population, a good agreement with available experimental data for temperatures 100–900 K is obtained.

The bound-electron $g$ factor is a stringent tool for tests of the standard model and the search for new physics. The comparison between an experiment on the $g$ factor of lithiumlike silicon and the two recent theoretical values revealed the discrepancies of $1.7\sigma$ [Glazov et al. Phys. Rev. Lett. 123, 173001 (2019)] and $5.2\sigma$ [Yerokhin et al. Phys. Rev. A 102, 022815 (2020)]. To identify the reason for this disagreement, we accomplish large-scale high-precision computation of the interelectronic-interaction and many-electron QED corrections. The calculations are performed within the extended Furry picture of QED, and the dependence of the final values on the choice of the binding potential is carefully analyzed. As a result, we significantly improve the agreement between the theory and experiment for the $g$ factor of lithiumlike silicon. We also report the most accurate theoretical prediction to date for lithiumlike calcium, which perfectly agrees with the experimental value.

In this Letter, we introduce a new paradigm for achieving robust asymmetric generation of acoustic vortex field through dual-layer metasurfaces by controlling their intrinsic topologic charges and the parity of geometry design. The underlying physics is contributed to the one-way process of orbital angular momentum (OAM) transition ensured by the broken spatial symmetry and the external topologic charge from the vortex diffraction. We further experimentally demonstrate this novel phenomenon. Our findings could provide new routes to manipulate the asymmetric response of vortex fields, including one-way excitation and propagation, and promise potential applications in passive OAM-based diodes.

Large protein complexes are assembled from protein subunits to form a specific structure. In our theoretic work, we propose that assembly into the correct structure could be reliably achieved through an assembly line with a specific sequence of assembly steps. Using droplet interfaces to position compartment boundaries, we show that an assembly line can be self-organized by active droplets. As a consequence, assembly steps can be arranged spatially so that a specific order of assembly is achieved and incorrect assembly is strongly suppressed.

This article presents groomed jet substructure measurements in $pp$ and $\mathrm{Pb}\text{−}\mathrm{Pb}$ collisions at $\sqrt{s_{NN}}=5.02\mathrm{TeV}$ with the ALICE detector. The soft drop grooming algorithm provides access to the hard parton splittings inside a jet by removing soft wide-angle radiation. We report the groomed jet momentum splitting fraction, $z_g$, and the (scaled) groomed jet radius, ${\theta }_g$. Charged-particle jets are reconstructed at midrapidity using the anti-$k_T$ algorithm with resolution parameters $R=0.2$ and $R=0.4$. In heavy-ion collisions, the large underlying event poses a challenge for the reconstruction of groomed jet observables, since fluctuations in the background can cause groomed parton splittings to be misidentified. By using strong grooming conditions to reduce this background, we report these observables fully corrected for detector effects and background fluctuations for the first time. A narrowing of the ${\theta }_g$ distribution in $\mathrm{Pb}\text{−}\mathrm{Pb}$ collisions compared to $pp$ collisions is seen, which provides direct evidence of the modification of the angular structure of jets in the quark-gluon plasma. No significant modification of the $z_g$ distribution in $\mathrm{Pb}\text{−}\mathrm{Pb}$ collisions compared to $pp$ collisions is observed. These results are compared with a variety of theoretical models of jet quenching, and provide constraints on jet energy-loss mechanisms and coherence effects in the quark-gluon plasma.

Collective resonance of interacting particles has important implications in many-body quantum systems and their applications. Strong interactions can lead to a blockade that prohibits the excitation of a collective resonance of two or more nearby atoms. However, a collective resonance can be excited with the presence of weak interaction and has been observed for atoms in the first excited state ($P$ state). Here, we report the observation of collective resonance of rubidium atoms in a higher excited state ($D$ state) in addition to the first excited state. The collective resonance is excited by a double-quantum four-pulse excitation sequence. The resulting double-quantum two-dimensional (2D) spectrum displays well-isolated peaks that can be attributed to collective resonances of atoms in $P$ and $D$ states. The experimental one-quantum and double-quantum 2D spectra can be reproduced by a simulation based on the perturbative solutions to the optical Bloch equations, confirming collective resonances as the origin of the measured spectra. The experimental technique provides a new approach for preparing and probing collective resonances of atoms in highly excited states.

Incorporating optical surface waves in nonlinear processes unlocks unique and sensitive nonlinear interactions wherein highly confined surface states can be accessed and explored. Here, we unravel the rich physics of modal-nonmodal state pairs of short-range surface plasmons in thin metal films by leveraging “dark nonlinearity”—a nonradiating nonlinear source. We control and observe the nonlinear forced response of these modal-nonmodal pairs and present nonlinearly mediated direct access to nonmodal plasmons in a lossless regime. Our study can be generalized to other forms of surface waves or optical nonlinearities, toward on-chip nonlinearly controlled nanophotonic devices.

Magnetic measurements during dc helicity injection tokamak startup indicate Alfvénic turbulence in the injected current streams mediates magnetic relaxation and results in macroscopic plasma current drive. Localization of such activity to the injected current streams, a bias voltage dependence to its onset, and higher-order spectral analysis indicate super-Alfvénic electrons excite instabilities that drive the observed turbulence. Measured fluctuation helicity is consistent with an $\alpha$-dynamo electromotive force driving net current comparable to the macroscopic equilibrium current density. These results imply new constraints for scaling local helicity injection to larger devices.

Orbital memory is defined by two stable valencies that can be electrically switched and read out. To explore the influence of an electric field on orbital memory, we studied the distance-dependent influence of an atomic Cu donor on the state favorability of an individual Co atom on black phosphorus. Using low temperature scanning tunneling microscopy and spectroscopy, we characterized the electronic properties of individual Cu donors, corroborating this behavior with ab initio calculations based on density functional theory. We studied the influence of an individual donor on the charging energy and stochastic behavior of an individual Co atom. We found a strong impact on the state favorability in the stochastic limit. These findings provide quantitative information about the influence of local electric fields on atomic orbital memory.

By combining angle-resolved photoemission spectroscopy, scanning tunneling microscopy, atomic force microscope based piezoresponse force microscopy and first-principles calculations, we have studied the low-energy band structure, atomic structure, and charge polarization on the surface of a topological semimetal candidate ${\mathrm{TaNiTe}}_5$. Dirac-like surface states were observed on the (010) surface by angle-resolved photoemission spectroscopy, consistent with the first-principles calculations. On the other hand, piezoresponse force microscopy reveals a switchable ferroelectriclike polarization on the same surface. We propose that the noncentrosymmetric surface relaxation observed by scanning tunneling microscopy could be the origin of the observed ferroelectriclike state in this novel material. Our findings provide a new platform with the coexistence of a ferroelectriclike surface charge distribution and novel surface states.

The role of water in biological processes is studied in three reactions, namely, the Fe-CO bond rupture in myoglobin, GB1 unfolding, and insulin dimer dissociation. We compute both internal and external components of friction on relevant reaction coordinates. In all of the three cases, the cross-correlation between forces from protein and water is found to be large and negative that serves to reduce the total friction significantly, increase the calculated reaction rate, and weaken solvent viscosity dependence. The computed force spectrum reveals bimodal $1/f$ noise, suggesting the use of a non-Markovian rate theory.

Photons, acting as “flying qubits” in propagation geometries such as waveguides, appear unavoidably in the form of wave packets (pulses). The actual shape of the photonic wave packet as well as possible temporal and spectral correlations between the photons play a critical role in successful scalable computation. Currently, unentangled indistinguishable photons are considered a suitable resource for scalable photonic circuits. Here we show that using so-called coherent photon conversion, it is possible to construct flying-qubit gates which are not only insensitive to wave shapes of the photons and temporal and spectral correlations between them but which also fully preserve these wave shapes and correlations upon the processing. This allows the use of photons with correlations and purity in a very broad range for a scalable computation. Moreover, such gates can process entangled photonic wave packets even more effectively than unentangled ones.

Recent work has shown the effectiveness of tensor network methods for computing large deviation functions in constrained stochastic models in the infinite time limit. Here we show that these methods can also be used to study the statistics of dynamical observables at arbitrary finite time. This is a harder problem because, in contrast to the infinite time case, where only the extremal eigenstate of a tilted Markov generator is relevant, for finite time the whole spectrum plays a role. We show that finite time dynamical partition sums can be computed efficiently and accurately in one dimension using matrix product states and describe how to use such results to generate rare event trajectories on demand. We apply our methods to the Fredrickson-Andersen and East kinetically constrained models and to the symmetric simple exclusion process, unveiling dynamical phase diagrams in terms of counting field and trajectory time. We also discuss extensions of this method to higher dimensions.