In quasicrystals lacking translational symmetry but having highly ordered structures, understanding how phonons propagate in their aperiodic lattices remains an unsolved issue. We present an inelastic neutron scattering study on acoustic phonon modes of icosahedral quasicrystal AlPdMn, revealing hierarchical pseudo-gap structure in low-energy acoustic modes. Additionally, phonon intensities are asymmetric in energy and wave vectors with respect to the Bragg peak, indicating characteristic nonreciprocal phonon propagation in quasicrystals.

We propose a general mechanism to realize nematic superconductivity (SC) and reveal its exotic vestigial phases in the quasicrystal (QC). Starting from a Penrose-Hubbard model, our microscopic studies suggest that the Kohn-Luttinger mechanism driven SC in the QC is usually gapless due to violation of Anderson’s theorem, rendering that both chiral and nematic SCs are common. The nematic SC in the QC can support novel vestigial phases driven by pairing phase fluctuations above its $T_c$. Our combined renormalization group and Monte Carlo studies provide a phase diagram in which, besides the conventional charge-$4e$ SC, two critical vestigial phases emerge, i.e., the quasinematic (QN) SC and QN metal. In the two QN phases, discrete lattice rotation symmetry is counterintuitively “quasibroken” with power-law decaying orientation correlation. They separate the phase diagram into various phases connected via Berezinskii-Kosterlitz-Thouless (BKT) transitions. These remarkable critical vestigial phases, which resemble the intermediate BKT phase in the $q$ state ($q\ge 5$) clock model, are a consequence of the fivefold (or higher) anisotropy field brought about by the unique QC symmetry, which are absent in conventional crystalline materials.

The transition from single to multiple atomic slips, theoretically expected and important in atomic-scale friction, has never been demonstrated experimentally as a function of velocity. Here we show by high-resolution friction force microscopy on monolayer ${\mathrm{MoS}}_2/\mathrm{Au}(111)$ that multiple slips leave a unique footprint—a frictional velocity weakening. Specifically, in a wide velocity interval from 10 to $100\mathrm{nm}/\mathrm{s}$, friction surprisingly decreases. Model simulations show a similar nonmonotonic behavior at velocities in quantitative agreement with experiment. Results suggest a velocity-corrugation phase diagram, whose validity is proposed more generally.

Spin dynamics is usually described as massless or, more precisely, as free of inertia. Recent experiments, however, found direct evidence for inertial spin dynamics. In turn, it is necessary to rethink the basics of spin dynamics. Focusing on a macrospin in an environment (bath), we show that the spin-to-bath coupling gives rise to spin inertia. This bath-induced spin inertia appears universally from all the high-frequency bath modes. We expect our results to provide new insights into recent experiments on spin inertia. Moreover, they indicate that any channel for spin dissipation should also be accompanied by a term accounting for bath-induced spin inertia. As an illustrative example, we consider phonon-bath-induced spin inertia in a YIG/GGG stack.

We prove the existence of extensive many-body Hamiltonians with few-body interactions and a many-body mobility edge: all eigenstates below a nonzero energy density are localized in an exponentially small fraction of “energetically allowed configurations” within Hilbert space. Our construction is based on quantum perturbations to a classical low-density parity check code. In principle, it is possible to detect this eigenstate localization by measuring few-body correlation functions in efficiently preparable mixed states.

We investigate the synapse-resolution connectomes of fruit flies across different developmental stages, revealing a consistent scaling law in neuronal connection probability relative to spatial distance. This power-law behavior significantly differs from the exponential distance rule previously observed in coarse-grained brain networks. We demonstrate that the geometric scaling law carries functional significance, aligning with the maximum entropy of information communication and the functional criticality balancing integration and segregation. Perturbing either the empirical probability model’s parameters or its type results in the loss of these advantageous properties. Furthermore, we derive an explicit quantitative predictor for neuronal connectivity, incorporating only interneuronal distance and neurons’ in and out degrees. Our findings establish a direct link between brain geometry and topology, shedding lights on the understanding of how the brain operates optimally within its confined space.

The weak interlayer interaction and strong intralayer bonding in Van der Waals (vdW) layered materials give rise to ultralow friction at incommensurate contact interfaces, a phenomenon known as structural superlubricity. This phenomenon is complicated by the interplay between atomic degrees of freedom, twist angle, and normal force. In this Letter, we exploit naturally occurring cracks in vdW crystals and microfabrication techniques to qualitatively separate the contributions of edge, complete moiré tile, and incomplete moiré rim regions. It is observed that friction from the incomplete moiré rim region, scaling linearly with the rim area, plays a dominant role in determining the twist angle dependence of friction. Interestingly, despite lower friction contributions from complete moirés, friction from a complete moiré tile is independent of moiré size; consequently, friction from the moiré tile scales linearly with the total number of moirés. By integrating the contributions from edge, moiré tile, and incomplete moiré rim, a friction law for vdW heterojunctions is proposed. Finally, friction changes from positively to negatively correlating with normal force, contingent on the suppression of moiré ridge and the dissipation from edge atoms.

Disorder or quasidisorder is known to favor localization in many-body Bose systems. Here, in contrast, we demonstrate an anomalous delocalization effect induced by incommensurability in quasiperiodic lattices. Loading ultracold atoms in two shallow periodic lattices with equal amplitude and either equal or incommensurate spatial periods, we show the onset of a Mott transition not only in the periodic case but also in the quasiperiodic case. Switching from periodic to quasiperiodic potential with the same amplitude, we find that the Mott insulator turns into a delocalized superfluid. Our experimental results agree with quantum Monte Carlo calculations, showing this anomalous delocalization induced by the interplay between the disorder and interaction.

Chiral phases of matter, characterized by a definite handedness, abound in nature, ranging from the crystal structure of quartz to spiraling spin states in helical magnets. In $1T\text{−}{\mathrm{TiSe}}_2$ a source of chirality has been proposed that stands apart from these classical examples as it arises from combined electronic charge and quantum orbital fluctuations. This may allow its chirality to be accessed and manipulated without imposing either structural or magnetic handedness. However, direct bulk evidence that broken inversion symmetry and chirality are intrinsic to ${\mathrm{TiSe}}_2$ remains elusive. Here, employing resonant elastic x-ray scattering technique, we reveal the presence of circular dichroism, i.e., polarization dependence of the resonant diffraction intensity, up to $\sim 40\%$ at forbidden Bragg peaks that emerge at the charge and orbital ordering transition. The dichroism varies dramatically with incident energy and azimuthal angle. Comparison to calculated scattering intensities traces its origin to bulk chiral electronic order in ${\mathrm{TiSe}}_2$ and establishes resonant elastic x-ray scattering as a sensitive probe to electronic chirality.

In single sheets of graphene, vacancy-induced states have been shown to host an effective spin-$1/2$ hole that can be Kondo screened at low temperatures. Here, we show how these vacancy-induced impurity states survive in twisted bilayer graphene (TBG), which thus provides a tunable system to probe the critical destruction of the Kondo effect in pseudogap hosts. Ab initio calculations and atomic-scale modeling are used to determine the nature of the vacancy states in the vicinity of the magic angle in TBG, demonstrating that the vacancy can be treated as a quantum impurity. Utilizing this insight, we construct an Anderson impurity model with a TBG host that we solve using the numerical renormalization group combined with the kernel polynomial method. We determine the phase diagram of the model and show how there is a strict dichotomy between vacancies in the $\mathrm{AA}/\mathrm{BB}$ versus $\mathrm{AB}/\mathrm{BA}$ tunneling regions. In $\mathrm{AB}/\mathrm{BA}$ vacancies, the Kondo temperature at the magic angle develops a broad distribution with a tail to vanishing temperatures due to multifractal wave functions at the magic angle. We argue that scanning tunneling microscopy in the vicinity of the vacancy can act as a probe of both the critical single-particle states and the underlying many-body ground state in magic-angle TBG.

Recent measurements of the four-point correlation function in large-scale galaxy surveys have found apparent evidence of parity violation in the distribution of galaxies. This cannot happen via dynamical gravitational effects in general relativity. If such a violation arose from physics in the early Universe it could indicate important new physics beyond the standard model, and would be at odds with most models of inflation. It is therefore now timely to consider the galaxy trispectrum in more detail. While the intrinsic four-point correlation function, or equivalently the trispectrum, its Fourier counterpart, is parity invariant, the observed trispectrum must take redshift-space distortions into account. Although the standard Newtonian correction also respects parity invariance, we show that subleading relativistic corrections do not. We demonstrate that these can be significant at intermediate linear scales and are dominant over the Newtonian parity-invariant part around the equality scale and above. Therefore when observing the galaxy four-point correlation function, we should expect to detect parity violation on large scales.

We present a theoretical prediction of a phonon-mediated two-gap superconductivity in infinite-layer nickelates ${\mathrm{Nd}}_{1-x}{\mathrm{Sr}}_x{\mathrm{NiO}}_2$ by performing ab initio $GW$ and $GW$ perturbation theory calculations. Electron $GW$ self-energy effects significantly alter the characters of the two-band Fermi surface and enhance the electron-phonon coupling, compared with results based on density functional theory. Solutions of the fully $\mathbf{k}$-dependent anisotropic Eliashberg equations yield two dominant $s$-wave superconducting gaps—a large gap on a band of rare-earth Nd $d$ and interstitial orbital characters and a small gap on a band of transition-metal Ni $d$ character. Increasing hole doping induces a non-rigid-band response in the electronic structure, leading to a rapid drop of the superconducting $T_c$ in the overdoped regime in agreement with experiments.

As a distinctive feature unique to non-Hermitian systems, non-Hermitian skin effect displays fruitful exotic phenomena in one or higher dimensions, especially when conventional topological phases are involved. Among them, hybrid skin-topological effect is theoretically proposed recently, which exhibits anomalous localization of topological boundary states at lower-dimensional boundaries accompanied by extended bulk states. Here, we experimentally realize the hybrid skin-topological effect in a non-Hermitian phononic crystal. The phononic crystal, before tuning to be non-Hermitian, is an ideal acoustic realization of the Kane-Mele model, which hosts gapless helical edge states at the boundaries. By introducing a staggered distribution of loss, the spin-dependent edge modes pile up to opposite corners, leading to a direct observation of the spin-dependent hybrid skin-topological effect. Our Letter highlights the interplay between topology and non-Hermiticity and opens new routes to non-Hermitian wave manipulations.

We show that the existence of clouds of ultralight particles surrounding black holes during their cosmological history as members of a binary system can leave a measurable imprint on the distribution of masses and orbital eccentricities observable with future gravitational-wave detectors. Notably, we find that for nonprecessing binaries with chirp masses $\mathcal{M}\lesssim 10M_{\odot }$, formed exclusively in isolation, larger-than-expected values of the eccentricity, i.e., $e\gtrsim {10}^{-2}$ at gravitational-wave frequencies $f_{\mathrm{GW}}\simeq {10}^{-2}\mathrm{Hz}$, would provide tantalizing evidence for a new particle of mass between $[0.5,2.5]\times {10}^{-12}\mathrm{eV}$ in nature. The predicted evolution of the eccentricity can also drastically affect the in-band phase evolution and peak frequency. These results constitute unique signatures of boson clouds of ultralight particles in the dynamics of binary black holes, which will be readily accessible with the Laser Interferometer Space Antenna, as well as future midband and decihertz detectors.

Superradiant clouds of ultralight bosons can leave an imprint on the gravitational waveform of black hole binaries through “ionization” and “resonances.” We study the sequence of resonances as the binary evolves and show that there are only two possible outcomes, each with a distinct imprint on the waveform. If the cloud and the binary are nearly counterrotating, then the cloud survives in its original state until it enters the sensitivity band of future gravitational wave detectors, such as the Laser Interferometer Space Antenna. In all other cases, resonances destroy the cloud while driving the binary to corotate with it and its eccentricity close to a fixed point. This opens up the possibility of inferring the existence of a new boson from the statistical analysis of a population of black hole binaries.

We report on the realization of a quantum sensor based on trapped atom interferometry in an optical lattice for the measurement of atom-surface interactions, with sub-micrometer-level control of the mean atom-surface separation distance. The force sensor reaches a short-term sensitivity of $3.4\times {10}^{-28}\mathrm{N}$ at 1 s and a long-term stability of 4 qN ($4\times {10}^{-30}\mathrm{N}$). We perform force measurements in the $0–300\mathrm{\mu }\mathrm{m}$ range, and despite significant stray forces caused by adsorbed atoms on the surface, we obtain evidence of the Casimir-Polder force.

Solid-state cooling presents an energy-efficient and environmentally friendly alternative to traditional refrigeration technologies that rely on thermodynamic cycles involving greenhouse gases. However, conventional caloric effects face several challenges that impede their practical application in refrigeration devices. First, operational temperature conditions must align closely with zero-field phase-transition points; otherwise, the required driving fields become excessively large. However, phase transitions occur infrequently near room temperature. Additionally, caloric effects typically exhibit strong temperature dependence and are sizable only within relatively narrow temperature ranges. In this Letter, we employ first-principles simulation methods to demonstrate that light-driven phase transitions in polar oxide perovskites have the potential to overcome such limitations. Specifically, for the prototypical ferroelectric ${\mathrm{KNbO}}_3$ we illustrate the existence of giant “photocaloric” effects induced by light absorption ($\mathrm{\Delta }{S}_{\mathrm{PC}}\sim 100\mathrm{J}{\mathrm{K}}^{-1}{\mathrm{kg}}^{-1}$ and $\mathrm{\Delta }{T}_{\mathrm{PC}}\sim 10\mathrm{K}$) across a vast temperature range of several hundred Kelvin, encompassing room temperature. These findings are expected to be generalizable to other materials exhibiting similar polar behavior.

We show that the standard $1+1\mathrm{D}$ ${\mathbb{Z}}_2\times {\mathbb{Z}}_2$ cluster model has a noninvertible global symmetry, described by the fusion category $\mathrm{Rep}({\mathrm{D}}_8)$. Therefore, the cluster state is not only a ${\mathbb{Z}}_2\times {\mathbb{Z}}_2$ symmetry protected topological (SPT) phase, but also a noninvertible SPT phase. We further find two new commuting Pauli Hamiltonians for the other two $\mathrm{Rep}({\mathrm{D}}_8)$ SPT phases on a tensor product Hilbert space of qubits, matching the classification in field theory and mathematics. We identify the edge modes and the local projective algebras at the interfaces between these noninvertible SPT phases. Finally, we show that there does not exist a symmetric entangler that maps between these distinct SPT states.

We measure the light-driven response of a magnetic multilayer structure made of thin alternating layers of cobalt and platinum at the few-femtosecond timescale. Using attosecond magnetic circular dichroism, we observe how light rearranges the magnetic moment during and after excitation. The results reveal a sub-5 fs spike of magnetization in the platinum layer, which follows the shape of the driving pulse. With the help of time-dependent density functional theory, we interpret the observations as light-driven spin injection across the metallic layers of the structure. The light-triggered spin current is strikingly short, largely outpacing decoherence and dephasing. The findings suggest that the ability of shaping light fields in refined ways could be translated into shaping new forms of spin currents in materials.

We identify a new class of surface waves that arise at a plasma-liquid interface due to resonant coupling between discrete plasma pattern modes and a continuum of interfacial liquid surface wave modes. A wave mode is selected due to localized excitation by the plasma, and standing waves result when waves excited from different locations interact. These waves propagate with a slower phase velocity than traditional capillary waves, but exhibit the same damping behavior with respect to liquid viscosity. Surface tension does not appear to play a significant role. We propose a curvature-dependent Maxwell pressure mechanism to explain these nondispersive interfacial waves in the presence of plasma.