The microscopic origin of chirality, possible electric-field induced static rotational lattice deformation, and rotation-field induced electric polarization are investigated. By building up a realistic tight-binding model for the elemental Te crystal in terms of a symmetry-adapted basis, we identify the microscopic origin of the chirality and essential couplings among polar and axial vectors with the same time-reversal properties. Based on this microscopic model, we elucidate quantitatively that an interband process, driven by nearest-neighbor spin-dependent imaginary hopping, is the key factor in the electric-field induced rotation and its inverse response. From the symmetry point of view, these couplings and responses are characteristic and common to any chiral material, leading to a possible experimental approach to achieve absolute enantioselection by simultaneously applied electric and rotation fields, or a magnetic field and electric current, and so on, as a conjugate field of the chirality.

Flexoelectricity-based mechanical switching of ferroelectric polarization has recently emerged as a fascinating alternative to conventional polarization switching using electric fields. Here, we demonstrate hyperefficient mechanical switching of polarization exploiting metastable ferroelectricity that inherently holds a unique mechanical response. We theoretically predict that mechanical forces markedly reduce the coercivity of metastable ferroelectricity, thus greatly bolstering flexoelectricity-driven mechanical polarization switching. As predicted, we experimentally confirm the mechanical polarization switching via an unusually low mechanical force (100 nN) in metastable ferroelectric ${\mathrm{CaTiO}}_3$. Furthermore, the use of low mechanical forces narrows the width of mechanically writable nanodomains to sub-10 nm, suggesting an ultrahigh data storage density of $\ge 1\mathrm{Tbit}{\mathrm{cm}}^{-2}$. This Letter sheds light on the mechanical switching of ferroelectric polarization as a viable key element for next-generation efficient nanoelectronics and nanoelectromechanics.

We analytically compute the scanning tunneling microscopy (STM) signatures of integer-filled correlated ground states of the magic angle twisted bilayer graphene (TBG) narrow bands. After experimentally validating the strong-coupling approach at $\pm 4\text{electrons}/\text{moiré}$ unit cell, we consider the spatial features of the STM signal for 14 different many-body correlated states and assess the possibility of Kekulé distortion (KD) emerging at the graphene lattice scale. Remarkably, we find that coupling the two opposite graphene valleys in the intervalley-coherent (IVC) TBG insulators does not always result in KD. As an example, we show that the Kramers IVC state and its nonchiral U(4) rotations do not exhibit any KD, while the time-reversal-symmetric IVC state does. Our results, obtained over a large range of energies and model parameters, show that the STM signal and Chern number of a state can be used to uniquely determine the nature of the TBG ground state.

A quantum version of the Monge-Kantorovich optimal transport problem is analyzed. The transport cost is minimized over the set of all bipartite coupling states ${\rho }^{AB}$ such that both of its reduced density matrices ${\rho }^A$ and ${\rho }^B$ of dimension $N$ are fixed. We show that, selecting the quantum cost matrix to be proportional to the projector on the antisymmetric subspace, the minimal transport cost leads to a semidistance between ${\rho }^A$ and ${\rho }^B$, which is bounded from below by the rescaled Bures distance and from above by the root infidelity. In the single-qubit case, we provide a semianalytic expression for the optimal transport cost between any two states and prove that its square root satisfies the triangle inequality and yields an analog of the Wasserstein distance of the order of 2 on the set of density matrices. We introduce an associated measure of proximity of quantum states, called swap fidelity, and discuss its properties and applications in quantum machine learning.

The reduced transition probabilities for the $4_1^{+}\to 2_1^{+}$ and $2_1^{+}\to 0_1^{+}$ transitions in ${}^{92}\mathrm{Mo}$ and ${}^{94}\mathrm{Ru}$ and for the $4_1^{+}\to 2_1^{+}$ and $6_1^{+}\to 4_1^{+}$ transitions in ${}^{90}\mathrm{Zr}$ have been determined in this experiment making use of a multinucleon transfer reaction. These results have been interpreted on the basis of realistic shell-model calculations in the $f_{5/2}$, $p_{3/2}$, $p_{1/2}$, and $g_{9/2}$ proton valence space. Only the combination of extensive lifetime information and large scale shell-model calculations allowed the extent of the seniority conservation in the $N=50$ $g_{9/2}$ orbital to be understood. The conclusion is that seniority is largely conserved in the first $\pi g_{9/2}$ orbital.

Spontaneous symmetry breaking is a property of Hamiltonian equilibrium states which, in the thermodynamic limit, retain a finite average value of an order parameter even after a field coupled to it is adiabatically turned off. In the case of quantum spin models with continuous symmetry, we show that this adiabatic process is also accompanied by the suppression of the fluctuations of the symmetry generator—namely, the collective spin component along an axis of symmetry. In systems of $S=1/2$ spins or qubits, the combination of the suppression of fluctuations along one direction and of the persistence of transverse magnetization leads to spin squeezing—a much sought-after property of quantum states, both for the purpose of entanglement detection as well as for metrological uses. Focusing on the case of $XXZ$ models spontaneously breaking a U(1) [or even SU(2)] symmetry, we show that the adiabatically prepared states have nearly minimal spin uncertainty; that the minimum phase uncertainty that one can achieve with these states scales as $N^{-3/4}$ with the number of spins $N$; and that this scaling is attained after an adiabatic preparation time scaling linearly with $N$. Our findings open the door to the adiabatic preparation of strongly spin-squeezed states in a large variety of quantum many-body devices including, e.g., optical-lattice clocks.

Electrostatic gating confines and controls the transport of electrons in integrated circuits. Magnons, the quanta of spin waves of the magnetic order, are promising alternative information carriers, but difficult to gate. Here we report that superconducting strips on top of thin magnetic films can totally reflect magnons by their diamagnetic response to the magnon stray fields. The induced large frequency shifts unidirectionally block the magnons propagating normal to the magnetization. Two superconducting gates parallel to the magnetization create a magnonic cavity. The option to gate coherent magnons adds functionalities to magnonic devices, such as reprogrammable logical devices and increased couplings to other degrees of freedom.

Causality is fundamental to science, but it appears in several different forms. One is relativistic causality, which is tied to a spacetime structure and forbids signaling outside the future. A second is an operational notion of causation that considers the flow of information between physical systems and interventions on them. In [V. Vilasini and R. Colbeck, General framework for cyclic and fine-tuned causal models and their compatibility with space-time, Phys. Rev. A 106, 032204 (2022).], we propose a framework for characterizing when a causal model can coexist with relativistic principles such as no superluminal signaling, while allowing for cyclic and nonclassical causal influences and the possibility of causation without signaling. In a theory without superluminal causation, both superluminal signaling and causal loops are not possible in Minkowski spacetime. Here we demonstrate that if we only forbid superluminal signaling, superluminal causation remains possible and show the mathematical possibility of causal loops that can be embedded in a Minkowski spacetime without leading to superluminal signaling. The existence of such loops in the given spacetime could in principle be operationally verified using interventions. This establishes that the physical principle of no superluminal signaling is not by itself sufficient to rule out causal loops between Minkowski spacetime events. Interestingly, the conditions required to rule out causal loops in a spacetime depend on the dimension. Whether such loops are possible in three spatial dimensions remains an important open question.

This Letter reports on the first results from the Taiwan Axion Search Experiment with a Haloscope, a search for axions using a microwave cavity at frequencies between 4.707 50 and 4.798 15 GHz. Apart from the nonaxion signals, no candidates with a significance of more than 3.355 were found. The experiment excludes models with the axion-two-photon coupling $|g_{a\gamma \gamma }|\gtrsim 8.1\times {10}^{-14}{\mathrm{GeV}}^{-1}$, a factor of eleven above the benchmark Kim-Shifman-Vainshtein-Zakharov model, in the mass range $19.4687<m_a<19.8436\mu \mathrm{eV}$. It is also the first time that a haloscope experiment places constraints on $g_{a\gamma \gamma }$ in the mass region of $19.4687<m_a<19.7639\mu \mathrm{eV}$, reaching a sensitivity 3 orders of magnitude better than the limits obtained by nonhaloscope experiments.

Integrated technologies greatly enhance the prospects for practical quantum information processing and sensing devices based on trapped ions. High-speed and high-fidelity ion state readout is critical for any such application. Integrated detectors offer significant advantages for system portability and can also greatly facilitate parallel operations if a separate detector can be incorporated at each ion-trapping location. Here, we demonstrate ion quantum state detection at room temperature utilizing single-photon avalanche diodes (SPADs) integrated directly into the substrate of silicon ion trapping chips. We detect the state of a trapped ${\mathrm{Sr}}^{+}$ ion via fluorescence collection with the SPAD, achieving 99.92(1)% average fidelity in $450\mathrm{\mu }\mathrm{s}$, opening the door to the application of integrated state detection to quantum computing and sensing utilizing arrays of trapped ions.

Using a data sample corresponding to an integrated luminosity of $11.3{\mathrm{fb}}^{-1}$ collected at center-of-mass energies from 4.23 to 4.70 GeV with the BESIII detector, we measure the product of the $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\psi }_2(3823)$ cross section and the branching fraction $\mathcal{B}[{\psi }_2(3823)\to \gamma {\chi }_{c1}]$. For the first time, resonance structure is observed in the cross section line shape of $e^{+}{e}^{-}\to {\pi }^{+}{\pi }^{-}{\psi }_2(3823)$ with significances exceeding $5\sigma$. A fit to data with two coherent Breit-Wigner resonances modeling the $\sqrt{s}$-dependent cross section yields $M(R_1)=4406.9\pm 17.2\pm 4.5\mathrm{MeV}/c^2$, $\mathrm{\Gamma }(R_1)=128.1\pm 37.2\pm 2.3\mathrm{MeV}$, and $M(R_2)=4647.9\pm 8.6\pm 0.8\mathrm{MeV}/c^2$, $\mathrm{\Gamma }(R_2)=33.1\pm 18.6\pm 4.1\mathrm{MeV}$. Though weakly disfavored by the data, a single resonance with $M(R)=4417.5\pm 26.2\pm 3.5\mathrm{MeV}/c^2$, $\mathrm{\Gamma }(R)=245\pm 48\pm 13\mathrm{MeV}$ is also possible to interpret data. This observation deepens our understanding of the nature of the vector charmoniumlike states. The mass of the ${\psi }_2(3823)$ state is measured as $(3823.12\pm 0.43\pm 0.13)\mathrm{MeV}/c^2$, which is the most precise measurement to date.

Carbon burning is a key step in the evolution of massive stars, Type 1a supernovae and superbursts in x-ray binary systems. Determining the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ fusion cross section at relevant energies by extrapolation of direct measurements is challenging due to resonances at and below the Coulomb barrier. A study of the ${}^{24}\mathrm{Mg}(\alpha ,{\alpha }^{\prime }){}^{24}\mathrm{Mg}$ reaction has identified several $0^{+}$ states in ${}^{24}\mathrm{Mg}$, close to the ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ threshold, which predominantly decay to ${}^{20}\mathrm{Ne}(\text{ground state})+\alpha$. These states were not observed in ${}^{20}\mathrm{Ne}(\alpha ,{\alpha }_0){}^{20}\mathrm{Ne}$ resonance scattering suggesting that they may have a dominant ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ cluster structure. Given the very low angular momentum associated with sub-barrier fusion, these states may play a decisive role in ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ fusion in analogy to the Hoyle state in helium burning. We present estimates of updated ${}^{12}\mathrm{C}+{}^{12}\mathrm{C}$ fusion reaction rates.

Suspensions of DNA macromolecules (0.8 wppm, 60 kbp), modeled as finitely extensible nonlinear elastic dumbbells coupled to the Newtonian fluid, show drag reduction up to 27% at friction Reynolds number 180, saturating at the previously unachieved Weissenberg number $\simeq {10}^4$. At a large Weissenberg number, the drag reduction is entirely induced by the fully stretched polymers, as confirmed by the extensional viscosity field. The polymer extension is strongly non-Gaussian, in contrast to the assumptions of classical viscoelastic models.