We report the first search for a nonstandard-model resonance decaying into $\tau$ pairs in $e^{+}{e}^{-}\to {\mu }^{+}{\mu }^{-}{\tau }^{+}{\tau }^{-}$ events in the $3.6–10\mathrm{GeV}/c^2$ mass range. We use a $62.8{\mathrm{fb}}^{-1}$ sample of $e^{+}{e}^{-}$ collisions collected at a center-of-mass energy of 10.58 GeV by the Belle II experiment at the SuperKEKB collider. The analysis probes three different models predicting a spin-1 particle coupling only to the heavier lepton families, a Higgs-like spin-0 particle that couples preferentially to charged leptons (leptophilic scalar), and an axionlike particle, respectively. We observe no evidence for a signal and set exclusion limits at 90% confidence level on the product of cross section and branching fraction into $\tau$ pairs, ranging from 0.7 to 24 fb, and on the couplings of these processes. We obtain world-leading constraints on the couplings for the leptophilic scalar model for masses above $6.5\mathrm{GeV}/c^2$ and for the axionlike particle model over the entire mass range.

Phase separation of multicomponent lipid membranes is characterized by the nucleation and coarsening of circular membrane domains that grow slowly in time as $\sim t^{1/3}$, following classical theories of coalescence and Ostwald ripening. In this Letter, we study the coarsening kinetics of phase-separating lipid membranes subjected to nonequilibrium forces and flows transmitted by motor-driven gliding actin filaments. We experimentally observe that the activity-induced surface flows trigger rapid coarsening of noncircular membrane domains that grow as $\sim t^{2/3}$, a $2\mathsf{x}$ acceleration in the growth exponent compared to passive coalescence and Ostwald ripening. We analyze these results by developing analytical theories based on the Smoluchowski coagulation model and the phase field model to predict the domain growth in the presence of active flows. Our Letter demonstrates that active matter forces may be used to control the growth and morphology of membrane domains driven out of equilibrium.

The newly discovered Ruddlesden-Popper bilayer ${\mathrm{La}}_3{\text{Ni}}_2{\mathrm{O}}_7$ reaches a remarkable superconducting transition temperature $T_c\approx 80\mathrm{K}$ under a pressure of above 14 GPa. Here we propose a minimal bilayer two-orbital model of the high-pressure phase of ${\mathrm{La}}_3{\text{Ni}}_2{\mathrm{O}}_7$. Our model is constructed with the Ni-$3d_{x^2-y^2}$, $3d_{3z^2-r^2}$ orbitals by using Wannier downfolding of the density functional theory calculations, which captures the key ingredients of the material, such as band structure and Fermi surface topology. There are two electron pockets, $\alpha$, $\beta$, and one hole pocket, $\gamma$, on the Fermi surface, in which the $\alpha$, $\beta$ pockets show mixing of two orbitals, while the $\gamma$ pocket is associated with $\mathrm{Ni}\text{−}{d}_{3z^2-r^2}$ orbital. The random phase approximation spin susceptibility reveals a magnetic enhancement associated with the $d_{3z^2-r^2}$ state. A higher energy model with $\mathrm{O}\text{−}p$ orbitals is also provided for further study.

Anhydrous sodium hydroxide, a common and structurally simple compound, shows spectacular isotope effects: NaOD undergoes a first-order transition, which is absent in NaOH. By combining ab initio electronic structure calculations with Feynman path integrals, we show that NaOH is an unusual example of a quantum paraelectric: zero-point quantum fluctuations stretch the weak hydrogen bonds (HBs) into a region where they are unstable and break. By strengthening the HBs via isotope substitution or applied pressure, the system can be driven to a broken-symmetry antiferroelectric phase. In passing, we provide a simple quantitative criterion for HB breaking in layered crystals and show that nuclear quantum effects are crucial in paraelectric to ferroelectric transitions in hydrogen-bonded hydroxides.

We construct structural order parameters based on local angular and radial distribution functions in dense colloidal suspensions. All the order parameters show significant correlations to local dynamics in the supercooled and glass regime. In particular, the correlations between the orientational order and dynamical heterogeneity are consistently higher than those between the conventional two-body structural entropy and local dynamics. The structure-dynamics correlations can be explained by a excitation model with the energy barrier depending on local structural order. Our results suggest that in dense disordered packings, local orientational order is higher than translational order, and plays a more important role in determining the dynamics in glassy systems.

We use electronic microwave control methods to implement addressed single-qubit gates with high speed and fidelity, for ${}^{43}{\mathrm{Ca}}^{+}$ hyperfine “atomic clock” qubits in a cryogenic (100 K) surface trap. For a single qubit, we benchmark an error of $1.5\times {10}^{-6}$ per Clifford gate (implemented using 600 ns $\pi /2$ pulses). For 2 qubits in the same trap zone (ion separation $5\mathrm{\mu }\mathrm{m}$), we use a spatial microwave field gradient, combined with an efficient four-pulse scheme, to implement independent addressed gates. Parallel randomized benchmarking on both qubits yields an average error $3.4\times {10}^{-5}$ per addressed $\pi /2$ gate. The scheme scales theoretically to larger numbers of qubits in a single register.

We report a deterministic and exact protocol to reverse any unknown qubit-unitary operation, which simulates the time inversion of a closed qubit system. To avoid known no-go results on universal deterministic exact unitary inversion, we consider the most general class of protocols transforming unknown unitary operations within the quantum circuit model, where the input unitary operation is called multiple times in sequence and fixed quantum circuits are inserted between the calls. In the proposed protocol, the input qubit-unitary operation is called 4 times to achieve the inverse operation, and the output state in an auxiliary system can be reused as a catalyst state in another run of the unitary inversion. We also present the simplification of the semidefinite programming for searching the optimal deterministic unitary inversion protocol for an arbitrary dimension presented by M. T. Quintino and D. Ebler [Quantum 6, 679 (2022)]. We show a method to reduce the large search space representing all possible protocols, which provides a useful tool for analyzing higher-order quantum transformations for unitary operations.

Studies of noncommutative gauge theory have mainly focused on noncommutative spacetimes with constant noncommutative structure, with little known about actions for noncommutative 4D Yang-Mills theory beyond this case. We construct an action for Yang-Mills theory on a quadratically noncommutative spacetime, i.e., of quantum-plane type, obtained from a Drinfeld twist, with star-gauge symmetry. Applied to supersymmetric Yang-Mills theory, this gives a candidate $\mathrm{AdS}/\mathrm{CFT}$ dual of string theory on a related deformation of ${\mathrm{AdS}}_5\times {\mathrm{S}}^5$, which is expected to be integrable in the planar limit.

We report on the first search for $\overline{\mathrm{\Lambda }}\text{−}\mathrm{\Lambda }$ oscillations in the decay $J/\psi \to p{K}^{-}\overline{\mathrm{\Lambda }}+\mathrm{c}.\mathrm{c}.$ by analyzing $1.31\times {10}^{9}J/\psi$ events accumulated with the BESIII detector at the BEPCII collider. The $J/\psi$ events are produced using $e^{+}{e}^{-}$ collisions at a center of mass energy $\sqrt{s}=3.097\mathrm{GeV}$. No evidence for hyperon oscillations is observed. The upper limit for the oscillation rate of $\overline{\mathrm{\Lambda }}$ to $\mathrm{\Lambda }$ hyperons is determined to be $\mathcal{P}(\mathrm{\Lambda })=[\mathcal{B}(J/\psi \to p{K}^{-}\mathrm{\Lambda }+\mathrm{c}.\mathrm{c}.)/\mathcal{B}(J/\psi \to p{K}^{-}\overline{\mathrm{\Lambda }}+\mathrm{c}.\mathrm{c}.)]<4.4\times {10}^{-6}$ corresponding to an oscillation parameter $\delta m_{\mathrm{\Lambda }\overline{\mathrm{\Lambda }}}$ of less than $3.8\times {10}^{-18}\mathrm{GeV}$ at the 90% confidence level.

The dependence of the ratio between the $B_s^0$ and $B^{+}$ hadron production fractions, $f_s/f_u$, on the transverse momentum ($p_T$) and rapidity of the $B$ mesons is studied using the decay channels $B_s^0\to J/\psi \varphi$ and $B^{+}\to J/\psi K^{+}$. The analysis uses a data sample of proton-proton collisions at a center-of-mass energy of 13 TeV, collected by the CMS experiment in 2018 and corresponding to an integrated luminosity of $61.6{\mathrm{fb}}^{-1}$. The $f_s/f_u$ ratio is observed to depend on the $B$ $p_T$ and to be consistent with becoming asymptotically constant at large $p_T$. No rapidity dependence is observed. The ratio of the $B^0$ to $B^{+}$ meson production fractions, $f_d/f_u$, is also measured, for the first time in proton-proton collisions, using the $B^0\to J/\psi K^{*0}$ decay channel. The result is found to be within 1 standard deviation of unity and independent of $p_T$ and rapidity, as expected from isospin invariance.

Nonlinearity-induced asymmetric transport (AT) can be utilized for on-chip implementation of nonreciprocal devices that do not require odd-vector biasing. This scheme, however, is subject to a fundamental bound dictating that the maximum transmittance asymmetry is inversely proportional to the asymmetry intensity range (AIR) over which AT occurs. Contrary to the conventional wisdom, we show that the implementation of losses can lead to an increase of the AIR without deteriorating the AT. We develop a general theory that provides a new upper bound for AT in nonlinear complex systems and highlights the importance of their structural complexity and of losses. Our predictions are confirmed numerically and experimentally using a microwave complex network of coaxial cables.

Josephson tunnel junctions exhibit a supercurrent typically proportional to the sine of the superconducting phase difference $\varphi$. In general, a term proportional to $\cos (\varphi )$ is also present, alongside microscopic electronic retardation effects. We show that voltage pulses sharply varying in time prompt a significant impact of the $\cos (\varphi )$ term. Its interplay with the $\sin (\varphi )$ term results in a nonequilibrium fractional Josephson effect (NFJE) $\sim \sin (\varphi /2)$ in the presence of bound states close to zero frequency. Our microscopic analysis reveals that the interference of nonequilibrium virtual quasiparticle excitations is responsible for this phenomenon. We also analyze this phenomenon for topological Josephson junctions with Majorana bound states. Remarkably, the NFJE is independent of the ground state fermion parity unlike its equilibrium counterpart.

We study the collective behavior of interacting arrays of nanomagnetic tripods. These objects have six discrete moment states, in contrast to the usual two states of an Ising-like moment. Our experimental data demonstrate that triangular lattice arrays form a “tripod ice” that exhibits charge ordering among the effective vertex magnetic charges, in direct analogy to artificial kagome spin ice. The results indicate that the interacting tripods have effective moments that act as emergent local variables, with strong connections to the well-studied Potts and clock models. In addition, the tripod moments display a tendency toward a nearest neighbor alignment in our thermalized samples that separates this system from kagome spin ice. Our results open a path toward the study of the collective behavior of nonbinary moments that is unavailable in other physical systems.

Monolayers of colloidal particles at oil-water interfaces readily crystallize owing to electrostatic repulsion, which is often mediated through the oil. However, little attempts exist to control it using oil-soluble electrolytes. We probe the interactions among charged hydrophobic microspheres confined at a water-hexadecane interface and show that repulsion can be continuously tuned over orders of magnitude upon introducing nanomolar amounts of an organic salt into the oil. Our results are compatible with an associative discharging mechanism of surface groups at the particle-oil interface, similar to the charge regulation observed for charged colloids in nonpolar solvents.

Quantum theory admits ensembles of quantum nonlocality without entanglement (QNLWE). These ensembles consist of seemingly classical states (they are perfectly distinguishable and nonentangled) that cannot be perfectly discriminated with local operations and classical communication (LOCC). Here, we analyze QNLWE from a causal perspective, and show how to perfectly discriminate some of these ensembles using local operations and classical communication without definite causal order. Specifically, three parties with access to an instance of indefinite causal order—the Araújo-Feix–Baumeler-Wolf process—can perfectly discriminate the states in a QNLWE ensemble—the SHIFT ensemble—with local operations. Hence, this type of quantum nonlocality disappears at the expense of definite causal order while retaining classical communication. Our results thereby leverage the fact that LOCC is a conjunction of three constraints: local operations, classical communication, and definite causal order. Moreover, we show how multipartite generalizations of the Araújo-Feix–Baumeler-Wolf process are transformed into multiqubit ensembles that exhibit QNLWE. Such ensembles are of independent interest for cryptographic protocols and for the study of separable quantum operations unachievable with LOCC.

Polarization of the cosmic microwave background (CMB) is sensitive to new physics violating parity symmetry, such as the presence of a pseudoscalar “axionlike” field. Such a field may be responsible for early dark energy (EDE), which is active prior to recombination and provides a solution to the so-called Hubble tension. The EDE field coupled to photons in a parity-violating manner would rotate the plane of linear polarization of the CMB and produce a cross-correlation power spectrum of $E$- and $B$-mode polarization fields with opposite parities. In this Letter, we fit the $EB$ power spectrum predicted by the photon-axion coupling of the EDE model with a potential $V(\varphi )\propto [1-\cos (\varphi /f){]}^3$ to polarization data from Planck. We find that the unique shape of the predicted $EB$ power spectrum is not favored by the data and obtain a first constraint on the photon-axion coupling constant, ${g}=(0.04\pm 0.16)M_{\mathrm{Pl}}^{-1}$ (68% C.L.), for the EDE model that best fits the CMB and galaxy clustering data. This constraint is independent of the miscalibration of polarization angles of the instrument or the polarized Galactic foreground emission. Our limit on ${g}$ may have important implications for embedding EDE in fundamental physics, such as string theory.