We explore the dynamical response of the free surface of an ultrasoft solid driven by a localized moving pressure disturbance. Experiments reveal a steady V-shaped wake analogous to a surface Mach wedge. A simple geometric argument provides a qualitative explanation consistent with observations. A theoretical framework combining elastodynamic, capillary, and gravitational effects yields a generalized dispersion relation that smoothly interpolates between Kelvin’s theory of liquid interface wakes and Rayleigh’s theory of elastic surface waves. Our analysis explains the observed Mach-like behavior quantitatively while also emphasizing how elastodynamic effects can generate effective damping through radiative leakage. Together, our experiments and theory reveal the existence of a new regime that bridges fluid and solid surface-wave physics, offering new routes for probing the dynamics of soft interfaces.

The Aharonov-Bohm effect is one of the most surprising wonders of the quantum world. Its interpretation is debated between a physical significance of the potential versus nonlocality of quantum physics, ambiguity which cannot be resolved from all performed spatial interference experiments. We put forward the idea of replacing its study by flavor interferometry as observed in neutrino oscillations. The neutrino propagation through the crust of the Earth is affected by the constant scalar matter potential, with a phase shift between flavors and no force field anywhere. Here we show how to signal and experimentally disentangle this phase shift by its symmetry properties. The energy dependence of the neutrino-antineutrino asymmetry in the golden transition ${\nu }_{\mu }\to {\nu }_e$ allows for a clear separation of this matter component against the genuine asymmetry. Thus we find how to observe in a single experiment, like DUNE, the physical significance of the potential, the neutrino mass hierarchy, and the genuine matter-antimatter asymmetry in the lepton sector.

Flat hadron beam collisions, though expected to enhance peak luminosity by about an order of magnitude, have not yet been demonstrated. We identify a new mechanism in which the hourglass-induced synchrobetatron resonance, when coupled to unavoidable machine fluctuations, drives emittance transfer and degrades the flat-beam condition. This effect becomes a critical limitation for maintaining flat hadron beams on operational timescales. Using Electron-Ion Collider (EIC) parameters, we show that it imposes stringent tolerances on machine noise. We further demonstrate that a dynamic focusing scheme, implemented by combining sextupoles with crab cavities, suppresses the resonance and relaxes these constraints, providing a practical path toward robust flat-beam collisions in future lepton-hadron colliders.

We investigate low-frequency ac transport in the Su-Schrieffer-Heeger (SSH) chain with chiral disorder near the topological delocalization transition. Our key finding is that the formation of hybridized pairs of topological domain wall zero modes leads to the anomalous logarithmic scaling of the ac conductivity $\sigma (\omega )\sim \log \omega$ at criticality, and $\sigma (\omega )\sim {\omega }^{2|\delta |}{\log }^2\omega$ away from it. Using the combination of real-space renormalization group analysis and qualitative hybridization arguments, we demonstrate that the form of the scaling of ac conductivity at criticality stems directly from the stretched-exponential [$\psi (x)\sim e^{-s\sqrt{x}}$] spatial decay of zero-mode wave functions at the critical point.

We theoretically explore the low-energy behavior of a Josephson tunnel junction coupled to a finite-length, charge-biased transmission line and compare it to its flux-biased counterpart. For transmission lines of increasing length, we show that the low-energy charge-dependent energy bands of the charge-biased configuration can be exactly mapped onto those of the flux-biased system via a well-defined duality transformation of circuit parameters. In the limit of an infinitely long transmission line, the influence of boundary conditions vanishes, and both circuits reduce to a resistively shunted Josephson junction. This convergence reveals the system’s intrinsic self-duality and critical behavior. Our exact formulation of charge-flux duality provides a foundation for generalizations to more complex superconductor-insulator phase transitions.

The thermalizing dynamics of many-body systems is often described through the lens of the eigenstate thermalization hypothesis (ETH). ETH postulates that the statistical properties of observables, when expressed in the energy eigenbasis, are described by smooth functions, which also describe correlations among the matrix elements. However, the form of these functions is usually left undetermined, constituting a key missing component of the ETH framework. In this Letter, we investigate the structure of such smooth functions by focusing on their Fourier transform, recently identified as free cumulants. Using nonlinear hydrodynamics, we provide a prediction for the universal scaling of the late-time behavior of time-ordered free cumulants in the thermodynamic limit. The prediction is further corroborated by large-scale numerical simulations of several nonintegrable one-dimensional spin models that exhibit diffusive transport behavior. Good agreement is observed in both infinite and finite-temperature regimes and for a collection of local observables. Our results indicate that the smooth multipoint correlation functions within the ETH framework admit a universal hydrodynamic description at low frequencies.

We propose hardware-efficient schemes for implementing logical h and s gates transversally on the rotated surface code with reconfigurable neutral atom arrays. Our protocol for logical s gates utilizes the time dynamics of the data and ancilla qubits during syndrome extraction (SE). In particular, we move beyond traditional schemes where transversal logical gates take place between two SE rounds and instead embed our fold-transversal logical operation within a single SE round, leveraging the fact that data and ancilla qubits can be morphed into an unrotated surface code state halfway through an SE round. Under circuit noise, we observe that the performance of our s gate protocol is comparable to that of the quantum memory. For logical h gates, we first develop a simple strategy to rotate code patches efficiently with two sets of 2D acousto-optic deflectors (2D-AOD). We also propose a new transversal h gate protocol, based on the same principle as our s gate protocol, to remove the need for an additional set of 2D-AOD. Together with transversal logical cnot gates, our protocols complete a transversal logical Clifford gate set on the rotated surface code and allow for efficient implementation on neutral atom array platforms.

First order phase transitions are well motivated and extensively studied sources of gravitational waves (GWs) from the early Universe. The vacuum energy released during such transitions is assumed to be transferred primarily either to the expanding bubble walls, whose collisions source GWs, or to the surrounding plasma, producing sound waves and turbulence, which source GWs. In this Letter, we study an alternative possibility that has not yet been considered: the released energy gets transferred primarily to feebly interacting particles that do not form a coherent interacting plasma but simply free-stream individually. We develop the formalism to study the production of GWs from such configurations and demonstrate that such GW signals have qualitatively distinct characteristics compared with conventional sources and are potentially observable with near-future GW detectors.

The minimal coupling of massless fermions to gravity does not allow for their gravitational production solely based on the expansion of the Universe. We argue that this changes in the presence of realistic and potentially detectable stochastic gravitational wave backgrounds. We compute the resulting energy density of Weyl fermions at 1-loop using in-in formalism. If the initially massless fermions eventually acquire mass, this mechanism can explain the dark matter abundance in the Universe. Remarkably, it may be more efficient than conventional gravitational production of superheavy fermions.

In recent neutrino detectors, neutrons produced in neutrino reactions play an important role. Muon capture on oxygen nuclei is one of the processes that produce neutrons in water Cherenkov detectors. We measured neutron multiplicity in the process using cosmic ray muons that stop in the gadolinium-loaded Super-Kamiokande detector. For this measurement, neutron detection efficiency is obtained with the muon capture events followed by gamma rays to be ${50.2}_{-2.1}^{+2.0}\%$. By fitting the observed multiplicity considering the detection efficiency, we measure neutron multiplicity in muon capture as $P(0)=24\pm 3\%$, $P(1)=70_{-2}^{+3}\%$, $P(2)=6.1\pm 0.5\%$, $P(3)=0.38\pm 0.09\%$. This is the first measurement of the multiplicity of neutrons associated with muon capture on oxygen without neutron energy threshold.

We propose a novel method to probe gluon linear polarization via energy correlations in hard scattering processes. This approach exploits the characteristic $\cos 2\varphi$ azimuthal modulation in single- and two-point energy correlations within jets initiated by polarized gluons. In contrast to conventional techniques that rely on $k_t$ resummation or intricate jet substructure observables, our method offers a theoretically robust and experimentally accessible avenue for gluon polarimetry. We perform an all-order analysis within the Ciafaloni-Catani-Fiorani-Marchesini formalism, incorporating coherent branching effects to achieve improved precision. Our predictions can be tested at current and future facilities, including the LHC, RHIC, HERA, and the EIC.

Higher-order topological photonic systems typically host corner states that are exponentially localized. Here we uncover a distinct regime of uniformly delocalized higher-order topological modes, emerging from the interplay of multiple spatially varying Dirac mass terms under chiral symmetry. These modes exhibit uniform large-area, sublattice-locked profiles that remain pinned at zero energy, independent of system size. Crucially, their internal phase admits a tunable gauge degree of freedom, enabling controlled reconfiguration without loss of topological protection. This dual combination of uniform delocalization and gauge-controlled tunability bridges the gap between scalable optical mode area and robust topological protection, and we further confirm these predictions experimentally in photonic crystals, observing excellent agreement with theory. Our scheme is directly applicable to photonic mode design and enables the realization of robust, large-area topological optical devices.

Thomson-scattering signals can be significantly modified by convective gains associated with the stimulated Raman scattering and stimulated Brillouin scattering instabilities as the scattered light traverses the probe beam. Gain results in amplification and narrowing of the redshifted (i.e., Stokes) scattered light, whereas blueshifted (anti-Stokes) features are depleted and broadened, making the relative prominence of these features a key signature of gain. Neglecting to account for instability growth has been a ubiquitous source of error in previous Thomson-scattering measurements.

Although time-reversal and inversion symmetry constrain the angular momentum of each phonon mode to vanish, we show that the vacuum state of crystals with such symmetries can, nevertheless, exhibit finite angular momentum fluctuations, which persist at finite temperature. These fluctuations arise from quantum coherence between nondegenerate modes with noncollinear polarizations and are encoded in the off-diagonal components of the angular momentum operator. Their origin lies in the noncommutativity between the phonon Hamiltonian and angular momentum, which enables time-dependent rotational dynamics even in symmetric vacua. Using a minimal model, we provide an intuitive picture of this phenomenon in terms of beating between linearly polarized modes, which generates a finite instantaneous angular momentum while remaining symmetry forbidden in the mean. We further show that these vacuum fluctuations give rise to distinct finite-frequency spectral signatures and outline a concrete route for their detection using time-resolved spectroscopic probes sensitive to lattice polarization and symmetry. Our results identify a previously unexplored regime of lattice dynamics, revealing that even the symmetric phonon vacuum can harbor structured, dynamical angular-momentum correlations.

The dielectric constant of interfacial water is an important parameter, but its measurement has posed challenges, and no consensus has been reached on a generalized expression. We derived a formula for the interfacial dielectric constant of a buried interface using the slab model for a half-solvated sphere: ${ϵ}^{\prime }={ϵ}_1{ϵ}_2({ϵ}_2-{ϵ}_1+6)/2(2{ϵ}_2+{ϵ}_1)$, where ${ϵ}_1$ and ${ϵ}_2$ are the dielectric constants of the solid and liquid phases, respectively. We experimentally validated this expression using vibrational sum frequency generation and Fresnel factor calculations for interfaces of neutral alumina with water (${\mathrm{H}}_2\mathrm{O}$ and ${\mathrm{D}}_2\mathrm{O}$) and ${\mathrm{CH}}_3\mathrm{CN}$. This fills an important knowledge gap in the description of the dielectric constant of interfaces.

A range of unusual emergent behaviors have been reported in the charge-density-wave (CDW) state of the $A{\mathrm{V}}_3{\mathrm{Sb}}_5$ ($A=\mathrm{K}$, Rb, Cs) kagome metals, including a CDW formation process without soft phonons, which points to an unconventional CDW mechanism. Here, we use inelastic x-ray scattering to show that the CDW in ${\mathrm{KV}}_3{\mathrm{Sb}}_5$ forms via phonons that soften to zero energy at the CDW ordering vector ($L$ point) around $T_{\mathrm{CDW}}=78\mathrm{K}$. The intensity of soft phonons exhibits a remarkable in-plane anisotropy, extending over a much larger momentum range along $L\text{−}A$ relative to $L\text{−}H$, which leads to diffuse scattering common among $A{\mathrm{V}}_3{\mathrm{Sb}}_5$. Using first-principles calculations, we find that the momentum-dependent electron-phonon coupling (EPC) peaks at $L$ and exhibits the same in-plane anisotropy as the phonon softening. Conversely, the electronic susceptibility does not peak at $L$ and shows the opposite in-plane anisotropy. Our findings favor momentum-dependent EPC as the driving mechanism of the CDW in ${\mathrm{KV}}_3{\mathrm{Sb}}_5$, with a CDW formation process similar to that of transition metal dichalcogenides.