Quantum state transferring has been demonstrated using drones via entanglement distribution. Here, we demonstrate the first drone-based quantum task for quantum key distribution (QKD). Compact and polarization-maintaining acquisition, pointing, and tracking systems and QKD modules are developed and loaded on a homemade octocopter with a takeoff weight of 30 kg. Real-time QKD is performed over a 200 m distance with an 8.48 kHz average secret key rate using a polarization-coded decoy-state BB84 protocol. With the capability of secret key distribution using a drone, wireless communication can be expected with enhanced security in the quantum approach between mobile nodes toward a network.

This Letter reports a search for charge-parity ($CP$) symmetry violating nonstandard interactions (NSI) of neutrinos with matter using the NOvA Experiment, and examines their effects on the determination of the standard oscillation parameters. Data from ${\nu }_{\mu }({\overline{\nu }}_{\mu })\to {\nu }_{\mu }({\overline{\nu }}_{\mu })$ and ${\nu }_{\mu }({\overline{\nu }}_{\mu })\to {\nu }_e({\overline{\nu }}_e)$ oscillation channels are used to measure the effect of the NSI parameters ${ϵ}_{e\mu }$ and ${ϵ}_{e\tau }$. With 90% CL the magnitudes of the NSI couplings are constrained to be $|{ϵ}_{e\mu }|\lesssim 0.3$ and $|{ϵ}_{e\tau }|\lesssim 0.4$. A degeneracy at $|{ϵ}_{e\tau }|\approx 1.8$ is reported, and we observe that the presence of NSI limits sensitivity to the standard $CP$ phase ${\delta }_{CP}$.

Searches for pair-produced multijet signatures using data corresponding to an integrated luminosity of $128{\mathrm{fb}}^{-1}$ of proton-proton collisions at $\sqrt{s}=13\mathrm{TeV}$ are presented. A data scouting technique is employed to record events with low jet scalar transverse momentum sum values. The electroweak production of particles predicted in $R$-parity violating supersymmetric models is probed for the first time with fully hadronic final states. This is the first search for prompt hadronically decaying mass-degenerate higgsinos, and extends current exclusions on $R$-parity violating top squarks and gluinos.

We demonstrate a bipartition technique using a superlattice architecture to access correlations between alternating planes of a mesoscopic array of spin-3 chromium atoms trapped in a 3D optical lattice. Using this method, we observe that out-of-equilibrium dynamics driven by long-range dipolar interactions lead to spin anticorrelations between the two spatially separated subsystems. Our bipartite measurements reveal a subtle interplay between the anisotropy of the 3D dipolar interactions and that of the lattice structure, without requiring single-site addressing. We compare our results to theoretical predictions based on a truncated cumulant expansion and a new cluster semiclassical method that we use to investigate correlations at the microscopic scale. Comparison with a high-temperature analytical model reveals quantum thermalization at a high negative spin temperature.

Entanglement in hybrid quantum systems comprised of fundamentally different degrees of freedom, such as light and mechanics, is of interest for a wide range of applications in quantum technologies. Here, we propose to engineer bipartite entanglement between traveling acoustic phonons in a Brillouin active solid state system and the accompanying light wave. The effect is achieved by applying optical pump pulses to state-of-the-art waveguides, exciting a Brillouin Stokes process. This pulsed approach, in a system operating in a regime orthogonal to standard optomechanical setups, allows for the generation of entangled photon-phonon pairs, resilient to thermal fluctuations. We propose an experimental platform where readout of the optoacoustics entanglement is done by the simultaneous detection of Stokes and anti-Stokes photons in a two-pump configuration. The proposed mechanism presents an important feature in that it does not require initial preparation of the quantum ground state of the phonon mode.

Complete quantum control of a stationary quantum bit embedded in a quantum emitter is crucial for photonic quantum information technologies. Recently, the orbital degree of freedom in optically active quantum dots has emerged as a promising candidate. However, the essential ability to perform arbitrary rotations on orbital qubits remains elusive. Here, we demonstrate arbitrary rotation of a hole orbital qubit with direct phase control using picosecond optical pulses. This is achieved by inducing stimulated Raman transitions within $\mathrm{\Lambda }$ systems coupled via radiative Auger processes. This new capability enables direct control of polar and azimuth angles of the Bloch vector without requiring timed precession. Our results establish orbital states in solid-state quantum emitters as a viable resource for applications in high-speed quantum information processing.

Altermagnetism (AM), a newly discovered magnetic state, ingeniously integrates the properties of ferromagnetism and antiferromagnetism, representing a significant breakthrough in the field of magnetic materials. Despite experimental verification of some typical AM materials, such as MnTe and ${\mathrm{MnTe}}_2$, the pursuit of AM materials that feature larger spin splitting and higher transition temperature is still essential. Here, our research focuses on CrSb, which possesses Néel temperature of up to 700 K and giant spin splitting near the Fermi level ($E_F$). Utilizing high-resolution angle-resolved photoemission spectroscopy and density functional theory calculations, we meticulously map the three-dimensional electronic structure of CrSb. Our photoemission spectroscopic results on both (0001) and ($10\overline{1}0$) cleavages of CrSb collaboratively reveal unprecedented details on AM-induced band splitting, and subsequently pin down its unique bulk $g$-wave symmetry through quantitative analysis of the angular and photon-energy dependence of spin splitting. Moreover, the observed spin splitting reaches the magnitude of 0.93 eV near $E_F$, the most substantial among all confirmed AM materials. This Letter not only validates the nature of CrSb as a prototype $g$-wave-like AM material but also underscores its pivotal role in pioneering applications in spintronics.

In the presence of an external magnetic field, the Kitaev model could host either gapped topological anyons or gapless Majorana fermions. In $\alpha \text{−}{\mathrm{RuCl}}_3$, the gapped and gapless cases are only separated by a 30° rotation of the in-plane magnetic field vector. The presence or absence of the spectral gap is key for understanding the thermal transport behavior in $\alpha \text{−}{\mathrm{RuCl}}_3$. Here, we study the anisotropy of the oscillatory features of thermal conductivity in $\alpha \text{−}{\mathrm{RuCl}}_3$. We examine the oscillatory features of thermal conductivities ($\kappa //\mathrm{a}$, $\kappa //\mathrm{b}$) with fixed external fields and find distinct behavior for the gapped ($\mathrm{B}//\mathrm{a}$) and gapless ($\mathrm{B}//\mathrm{b}$) scenarios. Furthermore, we track the evolution of thermal resistivity (${\lambda }_a$) and its oscillatory features with the rotation of in-plane magnetic fields from $\mathrm{B}//\mathrm{b}$ to $\mathrm{B}//\mathrm{a}$. The thermal resistivity $\lambda (B,\varphi )$ displays distinct rotational symmetries before and after the emergence of the field-induced Kitaev spin liquid phase. These results suggest that oscillatory features of thermal conductivity in $\alpha \text{−}{\mathrm{RuCl}}_3$ are closely linked to the putative Kitaev spin liquid phase and its excitations.

Atomically thin semiconductors, encompassing both 2D materials and quantum wells, exhibit a pronounced enhancement of excitonic effects due to geometric confinement. Consequently, these materials have become foundational platforms for the exploration and utilization of excitons. Recent ab initio studies have demonstrated that phonons can substantially screen electron-hole interactions in bulk semiconductors and strongly modify the properties of excitons. While excitonic properties of atomically thin semiconductors have been the subject of extensive theoretical investigations, the role of phonon screening on excitons in atomically thin structures remains unexplored. In this Letter, we demonstrate via ab initio $GW$-Bethe-Salpeter equation calculations that phonon screening can have a significant impact on optical excitations in atomically thin semiconductors. We further show that the degree of phonon screening can be tuned by structural engineering. We focus on atomically thin GaN quantum wells embedded in AlN and identify specific phonons in the surrounding material, AlN, that dramatically alter the lowest-lying exciton in monolayer GaN via screening. Our studies provide new intuition beyond standard models into the interplay among structural properties, phonon characteristics, and exciton properties in atomically thin semiconductors, and have implications for future experiments.

Discrete time crystalline phases have attracted significant theoretical and experimental attention in the last few years. Such systems require a seemingly impossible combination of nonadiabatic driving and a finite-entropy long-time state, which, surprisingly, is possible in nonergodic systems. Previous works have often relied on disorder for the required nonergodicity; here, we describe the construction of a discrete time crystal (DTC) phase in nondisordered, nonintegrable Ising-type systems. After discussing the conditions for interacting and periodically driven systems to display such phases in general, we propose a concrete model and then provide approximate analytical arguments and direct numerical evidence that it satisfies the conditions and displays a DTC phase robust to local periodic perturbations.

It has been shown that entropy differences between certain states of perturbative quantum gravity can be computed without specifying an ultraviolet completion. This is analogous to the situation in classical statistical mechanics, where entropy differences are defined but absolute entropy is not. Unlike in classical statistical mechanics, however, the entropy differences computed in perturbative quantum gravity do not have a clear physical interpretation. Here we construct a family of perturbative black hole states for which the entropy difference can be interpreted as a relative counting of states. Conceptually, this Letter begins with the algebra of mass fluctuations around a fixed black hole background, and points out that while this is a type I algebra, it is not a factor and therefore has no canonical definition of entropy. As in previous work, coupling the mass fluctuations to quantum matter embeds the mass algebra within a type II factor, in which entropy differences (but not absolute entropies) are well defined. It is then shown that for microcanonical wave functions of mass fluctuation, the type II entropy difference equals the logarithm of the dimension of the extra Hilbert space that is needed to map one microcanonical window to another using gauge-invariant unitaries. The Letter closes with comments on type II entropy difference in a more general class of states, where the von Neumann entropy difference does not have a physical interpretation, but “one-shot” entropy differences do.

We provide strong evidence that the widely studied real two-Higgs-doublet model is inconsistent under renormalization due to quark-induced divergent $CP$ violation ($CP\mathrm{V}$). We identify the necessary ingredients for the $CP\mathrm{V}$ to enter the renormalization-group equations based on symmetry proprieties of the divergent diagrams. We demonstrate that while these ingredients are present starting at six loops, the divergent $CP\mathrm{V}$ is zero at that order due to approximate symmetries. We show that these symmetries are broken at seven loops and determine the parameter dependence of the resulting divergent $CP\mathrm{V}$.

Ultrashort pulses can excite or ionize molecules and populate coherent electronic wave packets, inducing complex dynamics. In this Letter, we simulate the coupled electron-nuclear dynamics upon ionization to different electronic wave packets of (deuterated) benzene and fluoro-benzene molecules, quantum mechanically and in full dimensionality. In fluoro-benzene, the calculations unravel both interstate and intrastate quantum interferences that leave clear signatures of attochemistry and charge-directed dynamics in the shape of the autocorrelation function. The latter are in agreement with experimental high-harmonic spectroscopy measurements of benzenes and fluoro-benzene.

Superconductivity in infinite layer nickelates ${\mathrm{Nd}}_{1-x}{\mathrm{Sr}}_x{\mathrm{NiO}}_2$ has so far been achieved only in thin films, raising questions on the role of substrates and interfaces. Given the challenges associated with their synthesis it is imperative to identify their intrinsic properties. We use resonant inelastic x-ray scattering to investigate the influence of the ${\mathrm{SrTiO}}_3$ capping layer on the excitations of ${\mathrm{Nd}}_{1-x}{\mathrm{Sr}}_x{\mathrm{NiO}}_2$ ($x=0$ and 0.2). Spin excitations are observed in parent and 20% doped ${\mathrm{Nd}}_{1-x}{\mathrm{Sr}}_x{\mathrm{NiO}}_2$ regardless of capping, proving that magnetism is intrinsic to infinite-layer nickelates and appears in a significant fraction of their phase diagram. In parent and superconducting ${\mathrm{Nd}}_{1-x}{\mathrm{Sr}}_x{\mathrm{NiO}}_2$, the spin excitations are slightly hardened in capped samples compared to the noncapped ones. Additionally, a weaker Ni-Nd charge transfer peak at $\sim 0.6\mathrm{eV}$ suggests that the hybridization between Ni $3d$ and Nd $5d$ orbitals is reduced in capped samples. From our data, capping induces only minimal differences in ${\mathrm{Nd}}_{1-x}{\mathrm{Sr}}_x{\mathrm{NiO}}_2$ and we phenomenologically discuss these differences based on the reconstruction of the ${\mathrm{SrTiO}}_3\text{−}{\mathrm{NdNiO}}_2$ interface and other mechanisms such as crystalline disorder.

Recent experiments on rhombohedral pentalayer graphene with a substrate-induced moiré potential have identified both Chern insulators and fractional quantum Hall states at zero magnetic field. Surprisingly, these states are observed in strong displacement fields where the effects of the moiré lattice are weak, and seem to be readily accessed without fine-tuning. To address these experimental puzzles, we study a model of interacting electrons in this geometry. Within self-consistent Hartree-Fock (SCHF) calculations, we find an isolated Chern band with small bandwidth and good quantum geometry. Exact diagonalization and density-matrix renormalization group calculations both confirm the band hosts fractional quantum Hall states without a magnetic field. Remarkably, the Chern band is stable at a wide range of angles, at four through six rhombohedral layers, at varying rhombohedral hopping parameters, and—most strikingly—survives in SCHF calculations when the moiré potential vanishes. In this limit, the state spontaneously breaks time-reversal and translation symmetry simultaneously, giving a topological crystalline state that we term the “anomalous Hall crystal.” We argue this is a general mechanism to create stable Chern bands in rhombohedral multilayer graphene, opening the door to studying the interplay between electronic topology, fractionalization, and spontaneous translation symmetry breaking.

The standard theoretical framework for fractional quantum anomalous Hall (FQAH) effect assumes an isolated flat Chern band in the single particle level. In this Letter, we challenge this paradigm for the FQAH effect recently observed in pentalayer rhombohedrally stacked graphene aligned with hexagonal boron nitride. We show that the external moiré superlattice potential is simply a perturbation in a model with continuous translation symmetry. Through Hartree-Fock calculations, we find that interaction opens a sizable remote-band gap, resulting in an isolated narrow $C=1$ Chern band at filling $\nu =1$. From exact diagonalization we identify FQAH phases at various fillings. However, the FQAH states also exist in calculations without any external moiré potential. We suggest that the quantum anomalous Hall (QAH) insulator at $\nu =1$ should be viewed as an interaction-driven topological Wigner crystal with QAH effect, which is subsequently pinned by a small moiré potential. The $C=1$ QAH crystal is robust with a crystal period around 10 nm in 4-layer, 5-layer, 6-layer, and 7-layer graphene systems. Our work suggests a new direction to explore the interplay between topology and FQAH with spontaneous crystal formation in the vanishing moiré potential limit. We also propose a new system to generate and control both honeycomb and triangular moiré superlattice potentials through Coulomb interaction from another control layer, which can stabilize or suppress the QAH crystal depending on the density of the control layer.

We show that topological flat minibands can be engineered in a class of narrow gap semiconductor films using only an external electrostatic superlattice potential. We demonstrate that, for realistic material parameters, these bands are capable of hosting correlated topological phases such as integer and fractional quantum anomalous Hall states and composite Fermi liquid phases at zero magnetic field. Our results provide a path toward the realization of fractionalized topological states in a broad range of materials.