We present a scalable protocol for suppressing errors during electron spin shuttling in silicon quantum dots. The approach maps the valley Hamiltonian to a Landau-Zener problem to model the nonadiabatic dynamics in regions of small valley splitting. An optimization refines the shuttling velocity profile over a single small segment of the shuttling path, allowing for fast shuttles and ensuring the spin and valley degrees of freedom are unentangled. The protocol reliably returns the valley state to the ground state at the end of the shuttle, after which the spin phase accumulation becomes predictable and is compensated with a single virtual $z$ rotation on the spin. The time cost and complexity of the error suppression is minimal and independent of the distance over which the spin is shuttled, and the maximum velocities imposed by valley physics are found to be orders of magnitude larger than shuttling speeds achieved experimentally so far. This protocol offers a chip-scale solution for high-fidelity quantum transport in silicon spin-based quantum computing devices.

We present a novel multimessenger approach for probing nonstandard neutrino properties through the detection of gravitational waves (GWs) from collapsing stellar cores and associated supernova explosions. We show that neutrino flavor conversion inside the proto-neutron star (PNS), motivated by physics beyond the standard model (BSM), can significantly boost PNS convection. This effect leads to large-amplitude GW emission over a wide frequency range during an otherwise relatively quiescent GW phase shortly after core bounce. Such a signal provides a promising new avenue for exploring nonstandard neutrino phenomena and other BSM physics impacting PNS convection.

By analyzing a data sample of $e^{+}{e}^{-}$ collisions with center-of-mass energy $\sqrt{s}=3.773\mathrm{GeV}$, corresponding to an integrated luminosity of $7.9{\mathrm{fb}}^{-1}$ collected with the BESIII detector operating at the BEPCII collider, we study semileptonic decays of the $D^{0(+)}$ mesons into the axial-vector meson $b_1(1235)$ via the decay $b_1(1235)\to \omega \pi$. The decay $D^0\to b_1(1235{)}^{-}{e}^{+}{\nu }_e$ is observed with a significance of $5.2\sigma$ after considering systematic uncertainty, while evidence for the decay $D^{+}\to b_1(1235{)}^0{e}^{+}{\nu }_e$ is obtained with a $3.1\sigma$ significance. The product branching fractions are determined to be $\mathcal{B}[D^0\to b_1(1235{)}^{-}{e}^{+}{\nu }_e]\times \mathcal{B}[b_1(1235{)}^{-}\to \omega {\pi }^{-}]=(0.72\pm 0.18_{-0.08}^{+0.06})\times {10}^{-4}$ and $\mathcal{B}[D^{+}\to b_1(1235{)}^0{e}^{+}{\nu }_e]\times \mathcal{B}[b_1(1235{)}^0\to \omega {\pi }^0]=(1.16\pm 0.44\pm 0.16)\times {10}^{-4}$, where the first uncertainties are statistical and the second systematic. The ratio of their partial decay widths is determined to be $\{\mathrm{\Gamma }[D^0\to b_1(1235{)}^{-}{e}^{+}{\nu }_e]/2\mathrm{\Gamma }[D^{+}\to b_1(1235{)}^0{e}^{+}{\nu }_e]\}=0.78\pm 0.19_{-0.05}^{+0.04}$, which is consistent with unity, predicted by isospin invariance, within uncertainties.

Compton scattering is a fundamental process in QED with broad applications, yet its theoretical description at high energies is challenged by substantial next-to-leading order corrections arising from double-logarithmic enhancements. To address this, we report the first calculation of the next-to-next-to-leading order (NNLO) total cross section with full electron mass dependence. Our analysis reveals that the NNLO correction, albeit still containing double logarithms, is numerically small due to a suppressing prefactor. By identifying the origin of these logarithms in a kinematic regime featuring a Glauber electron exchange, we successfully resum the leading logarithmic series to all orders, obtaining a compact result in terms of a modified Bessel function. The all-order structure reveals a suppression mechanism, which explains the rapid convergence of higher-order contributions. The combination of our NNLO calculation and all-orders resummation delivers a reliable and precise prediction, poised to serve the needs of high-precision experiments in the foreseeable future.

We discover a surprising relation between the collective motion of nucleons within atomic nuclei, traditionally understood to be driven by long-range correlations, and short-range nucleon-nucleon interactions. Specifically, we find that quadrupole collectivity in low-lying states of ${}^6\mathrm{Li}$ and ${}^{12}\mathrm{C}$, calculated with state-of-the-art ab initio techniques, is significantly influenced by two opposing $S$-wave contact couplings that subtly alter the surface oscillations of one largely deformed nuclear shape, without changing that shape’s overall contribution within the nucleus. The results offer new insights into the nature of emergent nuclear collectivity and its link to the underlying nucleon-nucleon interaction at short distances.

Studies have long suggested that shocks can undergo cyclical self-reformation as a type of shock nonstationarity. Until now, providing solid evidence for shock reformation in spacecraft observation and identifying its generating mechanisms remain challenging. In this Letter, by analyzing magnetospheric multiscale observations, we unambiguously identified shock reformation occurring in a quasiperpendicular shock. A 2D PIC simulation reproduces and explains the observed shock reformation. The result reveals that the shock reformation is driven by the ion-scale whistler waves, manifested in two distinct types: whistler precursor and modified two-stream instability whistlers. An interesting finding is that the two mechanisms compete and dominate the reformation at early and later stages, respectively. Our results not only provide evidence of ion-scale whistlers as mechanism driving shock reformation, but also demonstrate the detailed kinetic processes how it happens, offering valuable insights into shock dynamics.

Structural twirls form spontaneously in the domain wall networks of some moiré materials. We show that in heterobilayers, neighboring twirl chiralities tend to antialign, forming staggered patterns that are well described by antiferromagnetic lattice ${\varphi }^4$ theories. In moiré systems with triangular domains, this leads to frustration in the chirality configuration of the twirls and to hysteresis with respect to variation of the average twist angle and possibly other control parameters. We expect that in typical materials, the ordering temperature of twirls is about ${10}^3\mathrm{K}$, and that thermal fluctuations in individual twirl chiralities freeze below room temperature.

Recently, the non-Hermitian skin effect (NHSE) has attracted significant interest in condensed-matter physics due to its distinctive phenomenon of the bulk states’ localization at boundaries. With the establishment of non-Bloch framework, the NHSE can be characterized accurately using the generalized Brillouin zone in one-dimensional systems, and classified into $\mathbb{Z}$ and ${\mathbb{Z}}_2$ skin effects based on their current functional. Here, we experimentally demonstrate a 1D ${\mathbb{Z}}_2$ NHSE in a passive acoustic system using a bilayer sonic crystal with tailored lossy couplings. By introducing an artificial gauge field via staggered interlayer couplings, we establish spinful anomalous time-reversal symmetry, while tunable dissipation, implemented by sound-absorbing sponges in intracell coupling tubes, enables the ${\mathbb{Z}}_2$ NHSE. We observe spin-polarized skin localization, where spin-up and spin-down states accumulate sound at opposite ends of the structure. This effect is confirmed through band dispersion, spatial field mapping, and transmission spectroscopy. Our Letter presents the first purely passive platform for the ${\mathbb{Z}}_2$ NHSE in acoustics, opening avenues for spin-momentum locked wave control in non-Hermitian topological metamaterials.

Efficiently preparing approximate ground states of large, strongly correlated systems on quantum hardware is challenging, and yet, nature is innately adept at this. This has motivated the study of thermodynamically inspired approaches to ground-state preparation that aim to replicate cooling processes via imaginary-time evolution. However, synthesizing quantum circuits that efficiently implement imaginary-time evolution is itself difficult, with prior proposals generally adopting heuristic variational approaches or using deep block encodings. Here, we use the insight that quantum imaginary-time evolution is a solution of Brockett’s double-bracket flow and synthesize circuits that implement double-bracket flows coherently on the quantum computer. We prove that our double-bracket quantum imaginary-time evolution (DB-QITE) algorithm inherits the cooling guarantees of imaginary-time evolution. Concretely, each step is guaranteed to (i) decrease the energy of an initial approximate ground state by an amount proportional to the energy fluctuations of the initial state and (ii) increase the fidelity with the ground state. We provide gate counts for DB-QITE through numerical simulations in qrisp that demonstrate scenarios where DB-QITE outperforms quantum phase estimation. Thus, DB-QITE provides a means to systematically improve the approximation of a ground state using shallow circuits.

Optimal tuning of functional parameters in density functional theory approximations, based on enforcing the ionization potential theorem, is a method of choice for the nonempirical prediction of the electronic structure of finite systems. This method has recently been extended to the bulk limit, based on an ansatz that generalizes the ionization potential theorem to the removal of an electron from a localized Wannier orbital. This Wannier-localization-based optimal tuning method has been shown to be highly successful for a wide range of periodic systems, accurately predicting electronic and optical properties. However, a rigorous theoretical justification for its foundational ansatz has been lacking. Here, we establish an ionization potential condition for the removal of an electron from a Wannier-localized orbital, by extending the piecewise linearity and Janak’s theorems in density functional theory. We also provide numerical evidence supporting our theory.

Magnonic spin current generation in antiferromagnets has emerged as an important topic in spintronics, where a strong external magnetic field or a Dzyaloshinskii-Moriya interaction (DMI) is generally required. Recently, a type of antiferromagnets characterized by momentum-dependent nonrelativistic spin splitting bands, referred to as altermagnets, has offered an unprecedented approach to generating magnon spin current without the constraints of a magnetic field or DMI. Here, we demonstrate the magnon spin splitting Nernst effect (MSSNE) in the ${\mathrm{LuFeO}}_3$ films, where applying a longitudinal temperature gradient generates a transverse magnonic spin current. Four critical types of evidence support the observed MSSNE originating from the spin splitting of magnon bands, as further corroborated by the symmetry analysis, rather than the DMI. Our findings not only demonstrate the MSSNE but also highlight the intriguing magnonic properties in the altermagnets, which have emerged as a promising material platform for antiferromagnetic spintronic applications.

We investigate low-frequency noise in a spin-qubit device made in isotopically purified Si/Si-Ge. Observing sizable cross-correlations among energy fluctuations of different qubits, we conclude that these fluctuations are dominated by charge noise. At low frequencies, the noise spectra are not well described by a power law; instead, they reveal the presence of a few individual two-level fluctuators (TLFs). We demonstrate that the noise cross-correlations allow one to get information on the spatial location of such individual TLFs.

We introduce a data-informed quantum-classical dynamics (DIQCD) approach for predicting the evolution of an open quantum system. The equation of motion in DIQCD is a Lindblad equation with a flexible, time-dependent Hamiltonian that can be optimized to fit sparse and noisy data from local observations of an extensive open quantum system. We demonstrate the accuracy and efficiency of DIQCD for both experimental and simulated quantum devices. We show that DIQCD can predict entanglement dynamics of ultracold molecules (calcium fluoride) in optical tweezer arrays. DIQCD also successfully predicts carrier mobility in organic semiconductors (rubrene) with accuracy comparable to nearly exact numerical methods.

The use of high-precision measurements of the $g$ factor of single-electron ions is considered as a detailed probe for physics beyond the standard model. The contribution of the exchange of a hypothetical force-carrying scalar boson to the $g$ factor is calculated for the ground state of H-like ions and used to derive bounds on the parameters of that force. Similarly to the isotope shift, we employ the nuclide shift, i.e., the difference for elements with different proton and/or neutron numbers, in order to increase the experimental sensitivity to the new physics contribution. In particular we find, combining available measurements with current precision with different ions, that the coupling constant for the interaction between an electron and a proton can be constrained up to 3 orders of magnitude better than with the best current atomic data and theory.

Ising superconductivity allows in-plane upper critical magnetic fields to vastly surpass Pauli limit by locking the antiparallel electron spins of Cooper pairs in the out-of-plane direction. It was first explicitly demonstrated in fully two-dimensional monolayers of transition metal dichalcogenides with large spin-orbit coupling and broken inversion symmetry. Since then, several studies have shown that it can be present in layered bulk materials, too. In our previous study, we have clarified the underlying microscopic mechanism of Ising superconductivity in bulk, based on a reduced electronic coupling between superconducting layers due to intercalation by insulating layers and restricted inversion symmetry. But earlier studies suggest that, in some transition metal dichalcogenide polytypes, the Pauli paramagnetic limit is violated even without intercalation. Here, using heat capacity measurements we unambiguously demonstrate that the pristine noncentrosymmetric bulk $4{\mathrm{H}}_{\mathrm{a}}\text{−}{\mathrm{NbSe}}_2$ polytype significantly violates the Pauli limit. The band structure parameters obtained from ab initio calculations using the experimentally determined crystal structure are used in the theoretical model, which provides the microscopic mechanism of the Ising protection based solely on broken inversion symmetry.