Two-dimensional (2D) topological electronic insulators are known to give rise to gapless edge modes, which underlie low energy dynamics, including electrical and thermal transport. This has been thoroughly investigated in the context of quantum Hall phases, and time-reversal invariant topological insulators. Here we study the edge of a 2D, topologically trivial insulating phase, as a function of the strength of the electronic interactions and the steepness of the confining potential. For sufficiently smooth confining potentials, alternating compressible and incompressible stripes appear at the edge. Our findings signal the emergence of gapless edge modes which may give rise to finite conductance at the edge. This would suggest a novel scenario of a nontopological metal-insulator transition in clean 2D systems. The incompressible stripes appear at commensurate fillings and may exhibit broken translational invariance along the edge in the form of charge density wave ordering. These are separated by structureless compressible stripes.

The reaction coordinate describing a transition between reactant and product is a fundamental concept in the theory of chemical reactions. Within transition-path theory, a quantitative definition of the reaction coordinate is found in the committor, which is the probability that a trajectory initiated from a given microstate first reaches the product before the reactant. Here we develop an information-theoretic origin for the committor and show how selecting transition paths from a long ergodic equilibrium trajectory induces entropy production which exactly equals the information that system dynamics provide about the reactivity of trajectories. This equality of entropy production and dynamical information generation also holds at the level of arbitrary individual coordinates, providing parallel measures of the coordinate’s relevance to the reaction, each of which is maximized by the committor.

We consider the $N$ particle classical Riesz gas confined in a one-dimensional external harmonic potential with power-law interaction of the form $1/r^k$, where $r$ is the separation between particles. As special limits it contains several systems such as Dyson’s log-gas ($k\to 0^{+}$), the Calogero-Moser model ($k=2$), the 1D one-component plasma ($k=-1$), and the hard-rod gas ($k\to \infty$). Despite its growing importance, only large-$N$ field theory and average density profile are known for general $k$. In this Letter, we study the fluctuations in the system by looking at the statistics of the gap between successive particles. This quantity is analogous to the well-known level-spacing statistics which is ubiquitous in several branches of physics. We show that the variance goes as $N^{-b_k}$ and we find the $k$ dependence of $b_k$ via direct Monte Carlo simulations. We provide supporting arguments based on microscopic Hessian calculation and a quadratic field theory approach. We compute the gap distribution and study its system size scaling. Except in the range $-1<k<0$, we find scaling for all $k>-2$ with both Gaussian and non-Gaussian scaling forms.

We revisit the problem of extending the phase space of diffeomorphism-invariant theories to account for embeddings associated with the boundary of subregions. We do so by emphasizing the importance of a careful treatment of embeddings in all aspects of the covariant phase space formalism. In so doing we introduce a new notion of the extension of field space associated with the embeddings which has the important feature that the Noether charges associated with all extended corner symmetries are in fact integrable, but not necessarily conserved. We give an intuitive understanding of this description. We then show that the charges give a representation of the extended corner symmetry via the Poisson bracket, without central extension.

We develop a method for lattice QCD calculation of the two-photon exchange contribution to the muonic-hydrogen Lamb shift. To demonstrate its feasibility, we present the first lattice calculation with a gauge ensemble at $m_{\pi }=142\mathrm{MeV}$. By adopting the infinite-volume reconstruction method along with an optimized subtraction scheme, we obtain with statistical uncertainty $\mathrm{\Delta }{E}_{\mathrm{TPE}}=-28.9(4.9)\mu \mathrm{eV}+93.72\mu \mathrm{eV}/{\mathrm{fm}}^2·⟨r_p^2⟩$, or $\mathrm{\Delta }{E}_{\mathrm{TPE}}=37.4(4.9)\mu \mathrm{eV}$, which is consistent with the previous theoretical results in a range of $20–50\mu \mathrm{eV}$.

We compute the three-loop nonsinglet corrections to the photon-quark form factors taking into account the full dependence on the virtuality of the photon and the quark mass. We combine the method of differential equations in an effective way with expansions around regular and singular points. This allows us to obtain results for the form factors with an accuracy of about eight to twelve digits in the whole kinematic range.

We present an improved standard-model (SM) prediction for the dilepton decay of the neutral pion. The loop amplitude is determined by the pion transition form factor for ${\pi }^0\to {\gamma }^{*}{\gamma }^{*}$, for which we employ a dispersive representation that incorporates both spacelike and timelike data as well as short-distance constraints. The resulting SM branching fraction, $\text{Br}[{\pi }^0\to e^{+}{e}^{-}]=6.25(3)\times {10}^{-8}$, sharpens constraints on physics beyond the SM, including pseudoscalar and axial-vector mediators.

The polarization of the $\mathrm{\Lambda }$ and $\overline{\mathrm{\Lambda }}$ hyperons along the beam ($z$) direction, $P_z$, has been measured in Pb-Pb collisions at $\sqrt{s_{NN}}=5.02\mathrm{TeV}$ recorded with ALICE at the Large Hadron Collider (LHC). The main contribution to $P_z$ comes from elliptic flow-induced vorticity and can be characterized by the second Fourier sine coefficient $P_{z,s2}=⟨P_z\sin (2\phi -2{\mathrm{\Psi }}_2)⟩$, where $\phi$ is the hyperon azimuthal emission angle and ${\mathrm{\Psi }}_2$ is the elliptic flow plane angle. We report the measurement of $P_{z,s2}$ for different collision centralities and in the 30%–50% centrality interval as a function of the hyperon transverse momentum and rapidity. The $P_{z,s2}$ is positive similarly as measured by the STAR Collaboration in Au-Au collisions at $\sqrt{s_{NN}}=200\mathrm{GeV}$, with somewhat smaller amplitude in the semicentral collisions. This is the first experimental evidence of a nonzero hyperon $P_z$ in Pb-Pb collisions at the LHC. The comparison of the measured $P_{z,s2}$ with the hydrodynamic model calculations shows sensitivity to the competing contributions from thermal and the recently found shear-induced vorticity, as well as to whether the polarization is acquired at the quark-gluon plasma or the hadronic phase.

In the exothermic process of fission decay, an atomic nucleus splits into two or more independent fragments. Several aspects of nuclear fission are not properly understood, in particular the formation of the neck between the nascent fragments, and the subsequent mechanism of scission into two or more independent fragments. Using an implementation of time-dependent density functional theory, based on a relativistic energy density functional and including pairing correlations, we analyze the final phase of the process of induced fission of ${}^{240}\mathrm{Pu}$, and show that the timescale of neck formation coincides with the assembly of two $\alpha$-like clusters. Because of its much larger binding energy, the dynamical synthesis of ${}^4\mathrm{He}$ in the neck predominates over other light clusters, e.g., ${}^3\mathrm{H}$ and ${}^6\mathrm{He}$. At the instant of scission the neck ruptures exactly between the two $\alpha$-like clusters, which separate because of the Coulomb repulsion and are eventually absorbed by the two emerging fragments. The mechanism of light charged clusters formation at scission could also be linked to ternary fission.

The emergence of parity-time ($\mathcal{PT}$) symmetry has greatly enriched our study of symmetry-enabled non-Hermitian physics, but the realization of quantum $\mathcal{PT}$ symmetry faces an intrinsic issue of unavoidable symmetry-breaking Langevin noises. Here we construct a quantum pseudo-anti-$\mathcal{PT}$ (pseudo-$\mathcal{APT}$) symmetry in a two-mode bosonic system without involving Langevin noises. We show that the spontaneous pseudo-$\mathcal{APT}$ symmetry breaking leads to an exceptional point, across which there is a transition between different types of quantum squeezing dynamics; i.e., the squeezing factor increases exponentially (oscillates periodically) with time in the pseudo-$\mathcal{APT}$-symmetric (broken) region. Such dramatic changes of squeezing factors and quantum dynamics near the exceptional point are utilized for ultraprecision quantum sensing. These exotic quantum phenomena and sensing applications can be experimentally observed in two physical systems: spontaneous wave mixing nonlinear optics and atomic Bose-Einstein condensates. Our Letter offers a physical platform for investigating exciting $\mathcal{APT}$ symmetry physics in the quantum realm, paving the way for exploring fundamental quantum non-Hermitian effects and their quantum technological applications.

Nonreciprocity is critically important in modern wave technologies, yet its general principles and practical implementations continue to raise intense research interest, in particular in the context of broken reciprocity based on spatiotemporal modulation. Abrupt changes in time of the electromagnetic properties of a material have also been shown to replace spatial boundaries, supporting highly unusual wave-matter interactions in so-called time metamaterials. Here, we introduce nonreciprocity for temporal boundaries, demonstrating Faraday polarization rotation in a magnetoplasma with material properties abruptly switched in time. Our findings open new opportunities for time metamaterials, yielding new avenues for nonreciprocity with broad applicability for wave engineering.

Relativistic interactions between ultraintense ($>{10}^{18}\mathrm{W}{\mathrm{cm}}^{-2}$) laser pulses and magnetized underdense plasmas are known to produce few-cycle Cerenkov wake radiation in the terahertz (THz) domain. Using multidimensional particle-in-cell simulations, we demonstrate the possibility of generating high-field ($>100\mathrm{GV}{\mathrm{m}}^{-1}$) THz bursts from helium gas plasmas embedded in strong ($>100\mathrm{T}$) magnetic fields perpendicular to the laser path. We show that two criteria must be satisfied for efficient THz generation. First, the plasma density should be adjusted to the laser pulse duration for a strong resonant excitation of the electromagnetic plasma wake. Second, in order to mitigate the damping of the transverse wake component across the density gradients at the plasma exit, the ratio of the relativistic electron cyclotron and plasma frequencies must be chosen slightly above unity, but not too large, lest the wake be degraded. Such conditions lead the outgoing THz wave to surpass in amplitude the electrostatic wakefield induced in a similar, yet unmagnetized plasma.

We propose a new method for self-injection of high-quality electron bunches in the plasma wakefield structure in the blowout regime utilizing a “flying focus” produced by a drive beam with an energy chirp. In a flying focus the speed of the density centroid of the drive bunch can be superluminal or subluminal by utilizing the chromatic dependence of the focusing optics. We first derive the focal velocity and the characteristic length of the focal spot in terms of the focal length and an energy chirp. We then demonstrate using multidimensional particle-in-cell simulations that a wake driven by a superluminally propagating flying focus of an electron beam can generate GeV-level electron bunches with ultralow normalized slice emittance ($\sim 30\mathrm{nm}\mathrm{rad}$), high current ($\sim 17\mathrm{kA}$), low slice energy spread ($\sim 0.1\%$), and therefore high normalized brightness ($>{10}^{19}\mathrm{A}/{\mathrm{m}}^2/{\mathrm{rad}}^2$) in a plasma of density $\sim {10}^{19}{\mathrm{cm}}^{-3}$. The injection process is highly controllable and tunable by changing the focal velocity and shaping the drive beam current. Near-term experiments at FACET II where the capabilities to generate tens of kA, $<10\mathrm{fs}$ drivers are planned, could potentially produce beams with brightness near ${10}^{20}\mathrm{A}/{\mathrm{m}}^2/{\mathrm{rad}}^2$.

Any collisionless plasma possesses some “available energy” (AE), defined as that part of the thermal energy that can be converted into instabilities and turbulence. Here, we present a calculation of the AE carried by magnetically trapped electrons in a flux tube of collisionless plasma. The AE is compared with nonlinear simulations of the energy flux resulting from collisionless turbulence driven by trapped-electron modes in various magnetic geometries. The numerical calculation of AE is rapid and shows a strong correlation with the simulated energy fluxes, which can be expressed as a power law and understood in terms of a simple model.

The formation of large polarons has been proposed as reason for the high defect tolerance, low mobility, low charge carrier trapping, and low nonradiative recombination rates of lead halide perovskites. Recently, direct evidence for large-polaron formation has been reported from a 50% effective mass enhancement in angle-resolved photoemission of ${\mathrm{CsPbBr}}_3$ over theory for the orthorhombic structure. We present in-depth band dispersion measurements of ${\mathrm{CsPbBr}}_3$ and GW calculations, which lead to similar effective masses at the valence band maximum of $0.203\pm 0.016$ $m_0$ in experiment and 0.226 $m_0$ in orthorhombic theory. We argue that the effective mass can be explained solely on the basis of electron-electron correlation and large-polaron formation cannot be concluded from photoemission data.

Single-layer graphene subject to periodic lateral strains is an artificial crystal that can support boundary spectra with an intrinsic polarity. This is analyzed by comparing the effects of periodic magnetic fields and strain-induced pseudomagnetic fields that, respectively, break and preserve time-reversal symmetry. In the former case, a Chern classification of the superlattice minibands with zero total magnetic flux enforces single counterpropagating modes traversing each bulk gap on opposite boundaries of a nanoribbon. For the pseudomagnetic field, pairs of counterpropagating modes migrate to the same boundary where they provide well-developed valley-helical transport channels on a single zigzag edge. We discuss possible schemes for implementing this situation and their experimental signatures.

Topological materials with broken inversion symmetry can give rise to nonreciprocal responses, such as the current rectification controlled by magnetic fields via magnetochiral anisotropy. Bulk nonreciprocal responses usually stem from relativistic corrections and are always very small. Here we report our discovery that ${\mathrm{ZrTe}}_5$ crystals in proximity to a topological quantum phase transition present gigantic magnetochiral anisotropy, which is the largest ever observed to date. We argue that a very low carrier density, inhomogeneities, and a torus-shaped Fermi surface induced by breaking of inversion symmetry in a Dirac material are central to explain this extraordinary property.