We present the first purely theoretical calculation of the weak mixing angle in the $\overline{\mathrm{MS}}$ scheme at low energies by combining results from lattice QCD with perturbation theory. We discuss its correlation with the hadronic contribution to the anomalous magnetic moment of the muon and to the energy dependence of the electromagnetic coupling. We also compare the results with calculations using cross-section data as input. Implications for the standard model prediction of the mass of the $W$ boson are also discussed.

Magnetic excitations play a crucial role in understanding the color confinement of 4D Yang-Mills theory, and we have the monopole and the center vortex as plausible candidates to explain its mechanism. Under suitable compactified setups of 4D Yang-Mills theory, we can achieve different weakly coupled descriptions of confinement phenomena: The monopole mechanism takes place on ${\mathbb{R}}^3\times S^1$ with the double-trace deformation, and the center-vortex mechanism is effective on ${\mathbb{R}}^2\times T^2$ with the ’t Hooft flux. We unify these two semiclassical descriptions by showing the explicit relation between the monopole and center vortex.

The $e^{+}{e}^{-}\to D_s^{+}{D}_{s1}(2536{)}^{-}$ and $e^{+}{e}^{-}\to D_s^{+}{D}_{s2}^{*}(2573{)}^{-}$ processes are studied using data samples collected with the BESIII detector at center-of-mass energies from 4.530 to 4.946 GeV. The absolute branching fractions of $D_{s1}(2536{)}^{-}\to {\overline{D}}^{*0}{K}^{-}$ and $D_{s2}^{*}(2573{)}^{-}\to {\overline{D}}^0{K}^{-}$ are measured for the first time to be $(35.9\pm 4.8\pm 3.5)\%$ and $(37.4\pm 3.1\pm 4.6)\%$, respectively. The $e^{+}{e}^{-}\to D_s^{+}{D}_{s1}(2536{)}^{-}$ and $e^{+}{e}^{-}\to D_s^{+}{D}_{s2}^{*}(2573{)}^{-}$ cross sections are measured, and a resonant structure at around 4.6 GeV with a width of 50 MeV is observed in both processes with a statistical significance of $7.2\sigma$ and $15\sigma$, respectively. The state is observed for the first time in $e^{+}{e}^{-}\to D_s^{+}{D}_{s2}^{*}(2573{)}^{-}$ and could be the $Y(4626)$ found by the Belle oration in the $D_s^{+}{D}_{s1}(2536{)}^{-}$ final state, since they have similar masses and widths. There is also evidence for a structure at around 4.75 GeV in both processes.

The hydrodynamic attractor is a concept that describes universal equilibration behavior in which systems lose microscopic details before hydrodynamics becomes applicable. We propose a setup to observe hydrodynamic attractors in ultracold atomic gases, taking advantage of the fact that driving the two-body $s$-wave scattering length causes phenomena equivalent to isotropic fluid expansions. We specifically consider two-component fermions with contact interactions in three dimensions and discuss their dynamics under a power-law drive of the scattering length in a uniform system. By explicit computation, we derive a hydrodynamic relaxation model. We analytically solve their dynamics and find the hydrodynamic attractor solution. Our proposed method using the scattering length drive is applicable to a wide range of ultracold atomic systems, and our results establish these as a new platform for exploring hydrodynamic attractors.

Quantum multicriticality not only has fundamental research significance but also can promote the development of emerging quantum technologies, owing to its rich phase transition mechanisms and quantum resources. While theoretical studies have predicted the multicritical phenomena in the light-matter systems, the experimental demonstration remains elusive for the challenges of achieving the system’s ground or steady states in strong coupling regimes. Here, by implementing the quantum adiabatic algorithm and the dissipative-system variational quantum algorithm on nuclear magnetic resonance quantum simulator, we successfully demonstrate the tricritical phenomena both in the closed and open systems described by the two-axis Rabi model. The experimental results clearly show that, beyond the decoherence effect, dissipation leads to the emergence of a novel multicritical phenomenon: it splits the first-order phase transition line of the closed Rabi model, and doubles the tricritical point. Our work provides a feasible technique for engineering the open quantum systems and opens a new avenue for exploring nonequilibrium many-body physics.

We investigated the film spreading during the evaporation of submillimeter oil-in-water emulsion droplets on a solid surface, and observed a novel phenomenon where the film follows a two-layer spreading. In combination with the instability at the film front, the spreading front acquires a flowerlike pattern. The emergence of the two-layer structure is attributed to micelles within the oil film that yield an oscillating disjoining pressure. By considering both the slipping condition and the disjoining pressure, a scaling analysis is carried out that agrees well with the observed film spreading dynamics. The film spreading follows Tanner’s law initially, while it becomes faster at a later stage, where the film radius follows $r\sim t^{1/2}$ for weak slip and $r\sim t^{3/8}$ for strong slip conditions.

Dreicer generation is one of the main mechanisms of runaway electron generation in weakly ionized plasmas. It is often described as a diffusive flow from the Maxwellian core into high energies under the effect of the electric field. In this Letter we demonstrate a critical role of the binary nature of inelastic collisions in weakly ionized plasma during tokamak startup, where some electrons experience virtually no collisions during acceleration to the critical energy. We show that using the Fokker-Planck collisional operator can underestimate the Dreicer generation rate by several orders of magnitude.

Multiple scattering of waves presents challenges for imaging complex media but offers potential for their characterization. Its onset is actually governed by the scattering mean free path ${\ell }_s$ that provides crucial information on the medium microarchitecture. Here, we introduce a reflection matrix method designed to estimate this parameter from the time decay of the single scattering rate. Our method is first validated by an ultrasound experiment on a tissue-mimicking phantom before being applied in vivo to a human liver. This Letter opens important perspectives for quantitative imaging of heterogeneous media with waves, whether it be for nondestructive testing, biomedical, or geophysical applications.

Simulating strongly correlated systems with incommensurate order poses significant challenges for traditional finite-size-based approaches. Confining such a phase to a finite-size geometry can induce spurious frustration, with spin spirals in frustrated magnets being a typical example. Here, we introduce an Ansatz based on infinite projected entangled-pair states which overcomes these limitations and enables the direct search for the optimal spiral in the thermodynamic limit, with a computational cost that is independent of the spiral’s wavelength. Leveraging this method, we simulate the Heisenberg model on the anisotropic triangular lattice, which interpolates between the square and isotropic triangular lattice limits. Besides accurately reproducing the magnetically ordered phases with arbitrary wavelength, the simulations reveal a quantum spin liquid phase emerging between the Néel and spin spiral phases.

The prevailing consensus is that the sequential sharing of nonlocality in a Bell experiment requires generalized unsharp measurements, given that a sharp measurement inevitably destroys the entanglement of the shared state. In contrast, a recent work [A. Steffinlongo and A. Tavakoli, Projective measurements are sufficient for recycling nonlocality, Phys. Rev. Lett. 129, 230402 (2022)] demonstrated the sharing of nonlocality up to two sequential observers by employing projective measurement aided with local randomness. Here, we introduce a form of local randomness-assisted qubit projective measurement protocol that enables the sharing of nonlocality by an arbitrary number of sequential observers (Bobs) with a single spatially separated observer (Alice). We achieve this by inspecting the diversity involved in implementing generalized measurements that harness nonlocality by preserving a sufficient amount of entanglement of the shared two-qubit entangled state. Furthermore, we highlight the crucial interplay between the degrees of measurement incompatibility of Alice and Bob in demonstrating the unbounded sharing of nonlocality.

The Heisenberg limit [(HL), with estimation error scales as $1/n$] and the standard quantum limit (SQL, $\propto 1/\sqrt{n}$) are two fundamental limits in estimating an unknown parameter in $n$ copies of quantum channels and are achievable with full quantum controls, e.g., quantum error correction (QEC). It is unknown though, whether these limits are still achievable in restricted quantum devices when QEC is unavailable, e.g., with only unitary controls or bounded system sizes. In this Letter, we discover various new limits for estimating qubit channels under restrictive controls. The HL is shown to be unachievable in various cases, indicating the necessity of QEC in achieving the HL. Furthermore, a necessary and sufficient condition to achieve the SQL is determined, where a single-qubit unitary control protocol is identified to achieve the SQL for certain types of noisy channels, and for other cases a constant floor on the estimation error is proven. A practical example of the unitary protocol is provided.

We determine for the first time the renormalization-group equation for the three-particle $B$-meson soft function dictating the nonperturbative strong interaction dynamics of the long-distance penguin contributions to the double radiative $B$-meson decays. The distinctive feature of the ultraviolet renormalization of this fundamental soft function consists in the pattern of mixing positive into negative support for an arbitrary initial condition. The exact solution to this integrodifferential evolution equation is then derived with the Laplace transform technique, allowing for the model-independent extraction of the asymptotic behavior at large and small partonic momenta.

Recent experimental studies have questioned the validity of spin statistics assumptions, particularly in charge exchange processes occurring in atomic MeV collisions. Here, we study spin-resolved single electron capture processes in collisions between ${\mathrm{C}}^{3+}$ ions and helium within an energy range of $1.25–400\mathrm{keV}/\mathrm{u}$. Using high resolution reaction microscope and multielectronic theoretical approaches, we directly measure and calculate the true population information of the ${\mathrm{C}}^{2+}(1s^{2}2s2p{}^{1,3}P)$ states at the time of electron capture, overcoming the previous experimental and theoretical difficulties. At the level of integral and scattering angle differential cross sections, our results demonstrate the breakdown of pure spin statistics arguments, especially at high impact energies where they are traditionally expected to be valid. These novel findings and conclusions raise intriguing questions both in the understanding of the electronic dynamics during such fast collisional processes and in exploring quantum manipulation of atomic and molecular reactivity.

The facilitation of Rydberg excitations in a gas of atoms provides an ideal model system to study epidemic evolution on (dynamic) networks and self-organization of complex systems to the critical point of a nonequilibrium phase transition. Using Monte Carlo simulations and a machine learning algorithm we show that the universality class of this phase transition can be tuned but is robust against decay inherent to the self-organization process. The classes include directed percolation (DP), the most common class in short-range spreading models, and mean-field (MF) behavior, but also different types of anomalous directed percolation (ADP), characterized by rare long-range excitation processes. In a frozen gas, ground state atoms that can facilitate each other form a static network, for which we predict DP universality. With atomic motion the network becomes dynamic by long-range (Lévy-flight type) excitations. This leads to continuously varying critical exponents, varying smoothly between DP and MF values, corresponding to the ADP universality class. These findings also explain the recently observed critical exponent of Rydberg facilitation in an ultracold gas experiment [Helmrich et al., Nature (London) 577, 481 (2020)], which was in between DP and MF values.

We report a driven-dissipative mechanism to generate stationary entangled $W$ states among strongly interacting quantum emitters placed within a cavity. Driving the ensemble into the highest energy state—whether coherently or incoherently—enables a subsequent cavity-enhanced decay into an entangled steady state consisting of a single deexcitation shared coherently among all emitters, i.e., a $W$ state, well known for its robustness against qubit loss. The nonharmonic energy structure of the interacting ensemble allows this transition to be resonantly selected by the cavity, while quenching subsequent off-resonant decays. Evidence of this purely dissipative mechanism should be observable in state-of-the-art cavity QED systems in the solid state, enabling new prospects for the scalable stabilization of quantum states in dissipative quantum platforms.

A coherent perfect absorber exploits the interferometric nature of light to deposit all of a light field’s incident energy into an otherwise weakly absorbing sample. The downside of this concept is that the necessary destructive interference in coherent perfect absorbers gets easily destroyed both by spectrally or spatially detuning the incoming light field. Each of these two limitations has recently been overcome by insights from exceptional-point physics and by using a degenerate cavity, respectively. Here, we show how these two concepts can be combined into a new type of cavity design, which allows broadband exceptional-point absorption of arbitrary wavefronts. We present two possible implementations of such a massively degenerate exceptional-point absorber and compare analytical results with numerical simulations.

Traditional electronic devices rely on the electron’s intrinsic degrees of freedom (d.o.f.) to process information. However, additional d.o.f., like the valley, can emerge in the low-energy states of certain systems. Here, we show that the quantum dots constructed from two-dimensional second-order topological insulators posses a new kind of d.o.f., namely corner freedom, related to the topological corner states that reside at different corners of the systems. Since the corner states are well separated in real space, they can be individually and intuitively manipulated, giving rise to the concept of cornertronics. Via symmetry analysis and material search, we identify the TiSiCO-family monolayers as the first prototype of cornertronics materials, where the corner states can be controlled by both electric and optical fields due to novel corner-layer coupling effect and corner-contrasted linear dichroism. Furthermore, we find that the band gap of the TiSiCO nanodisk lies in the terahertz region and is robust to size reduction. These results indicate that the TiSiCO nanodisks can be used to design terahertz devices with ultrasmall size and electric-field tunable band gap. Besides, the TiSiCO nanodisks are simultaneously sensitive to both the strength and polarization of the terahertz waves. Our findings not only pave the way for cornertronics, but also open a new direction for research in two-dimensional second-order topological insulators, quantum dots, and terahertz electronics.