The occurrence of an inverse current, where the sign of the induced current is opposite to the applied force, is a highly counterintuitive phenomenon. We show that inverse currents in coupled transport (ICC) of energy and particle can occur in a one-dimensional interacting Hamiltonian system when its equilibrium state is perturbed by coupled thermodynamic forces. This seemingly paradoxical result is possible due to the self-organization occurring in the system in response to the applied forces.

A partial-wave analysis is performed for the process $e^{+}{e}^{-}\to K^{+}{K}^{-}{\pi }^0{\pi }^0$ at the center-of-mass energies ranging from 2.000 to 2.644 GeV. The data samples of $e^{+}{e}^{-}$ collisions, collected by the BESIII detector at the BEPCII collider with a total integrated luminosity of $300{\mathrm{pb}}^{-1}$, are analyzed. The total Born cross sections for the process $e^{+}{e}^{-}\to K^{+}{K}^{-}{\pi }^0{\pi }^0$, as well as the Born cross sections for the subprocesses $e^{+}{e}^{-}\to \varphi {\pi }^0{\pi }^0$, $K^{+}(1460)K^{-}$, $K_1^{+}(1400)K^{-}$, $K_1^{+}(1270)K^{-}$, and $K^{*+}(892)K^{*-}(892)$, are measured versus the center-of-mass energy. The corresponding results for $e^{+}{e}^{-}\to K^{+}{K}^{-}{\pi }^0{\pi }^0$ and $\varphi {\pi }^0{\pi }^0$ are consistent with those of BABAR with better precision. By analyzing the cross sections for the four subprocesses, $K^{+}(1460)K^{-}$, $K_1^{+}(1400)K^{-}$, $K_1^{+}(1270)K^{-}$, and $K^{*+}(892)K^{*-}(892)$, a structure with mass $M=(2126.5\pm 16.8\pm 12.4)\mathrm{MeV}/c^2$ and width $\mathrm{\Gamma }=(106.9\pm 32.1\pm 28.1)\mathrm{MeV}$ is observed with an overall statistical significance of $6.3\sigma$, although with very limited significance in the subprocesses $e^{+}{e}^{-}\to K_1^{+}(1270)K^{-}$ and $K^{*+}(892)K^{*-}(892)$. The resonant parameters of the observed structure suggest it can be identified with the $\varphi (2170)$, thus the results provide valuable input to the internal nature of the $\varphi (2170)$.

Feynman’s path integral approach is to sum over all possible spatiotemporal paths to reproduce the quantum wave function and the corresponding time evolution, which has enormous potential to reveal quantum processes in the classical view. However, the complete characterization of the quantum wave function with infinite paths is a formidable challenge, which greatly limits the application potential, especially in the strong-field physics and attosecond science. Instead of brute-force tracking every path one by one, here we propose a deep-learning-performed strong-field Feynman’s formulation with a preclassification scheme that can predict directly the final results only with data of initial conditions, so as to attack unsurmountable tasks by existing strong-field methods and explore new physics. Our results build a bridge between deep learning and strong-field physics through Feynman’s path integral, which would boost applications of deep learning to study the ultrafast time-dependent dynamics in strong-field physics and attosecond science and shed new light on the quantum-classical correspondence.

An elastic cloak is a coating material that can be applied to an arbitrary inclusion to make it indistinguishable from the background medium. Cloaking against elastic disturbances, in particular, has been demonstrated using several designs and gauges. None, however, tolerate the coexistence of normal and shear stresses due to a shortage of physical realization of transformation-invariant elastic materials. Here, we overcome this limitation to design and fabricate a new class of polar materials with a distribution of body torque that exhibits asymmetric stresses. A static cloak for full two-dimensional elasticity is thus constructed based on the transformation method. The proposed cloak is made of a functionally graded multilayered lattice embedded in an isotropic continuum background. While one layer is tailored to produce a target elastic behavior, the other layers impose a set of kinematic constraints equivalent to a distribution of body torque that breaks the stress symmetry. Experimental testing under static compressive and shear loads demonstrates encouraging cloaking performance in good agreement with our theoretical prediction. The work sets a precedent in the field of transformation elasticity and should find applications in mechanical stress shielding and stealth technologies.

The analytical two-chain Frenkel-Kontorova model is used to describe domain wall networks in bilayer graphene upon biaxial stretching of one of the layers. We show that the commensurate-incommensurate phase transition leading to formation of a regular triangular domain wall network at the relative biaxial elongation of $3.0\times {10}^{-3}$ is followed by the transition to another incommensurate phase with a striped network at the elongation of $3.7\times {10}^{-3}$. The reentrant transition to the phase with a triangular domain wall network is predicted for the elongation $\sim {10}^{-2}$.

Momentum transport is anomalous in chiral $p+ip$ superfluids and superconductors in the presence of textures and superflow. Using the gradient expansion of the semiclassical approximation, we show how gauge and Galilean symmetries induce an emergent curved spacetime with torsion and curvature for the quasirelativistic low-energy Majorana-Weyl quasiparticles. We explicitly show the emergence of the spin connection and curvature, in addition to torsion, using the superfluid hydrodynamics. The background constitutes an emergent quasirelativistic Riemann-Cartan spacetime for the Weyl quasiparticles which satisfy the conservation laws associated with local Lorentz symmetry restricted to the plane of uniaxial anisotropy of the superfluid (or superconductor). Moreover, we show that the anomalous Galilean momentum conservation is a consequence of the gravitational Nieh-Yan (NY) chiral anomaly the Weyl fermions experience on the background geometry. Notably, the NY anomaly coefficient features a nonuniversal ultraviolet cutoff scale $\mathrm{\Lambda }$, with canonical dimensions of momentum. Comparison of the anomaly equation and the hydrodynamic equations suggests that the value of the cutoff parameter $\mathrm{\Lambda }$ is determined by the normal state Fermi liquid and nonrelativistic uniaxial symmetry of the $p$-wave superfluid or superconductor.

We report a chemical substitution-induced ferromagnetic quantum critical point in polycrystalline ${\mathrm{Ni}}_{1-x}{\mathrm{Rh}}_x$ alloys. Through magnetization and muon spin relaxation measurements, we show that the ferromagnetic ordering temperature is suppressed continuously to zero at $x_{\mathrm{crit}}=0.375$ while the magnetic volume fraction remains 100% up to $x_{\mathrm{crit}}$, pointing to a second order transition. Non-Fermi liquid behavior is observed close to $x_{\mathrm{crit}}$, where the electronic specific heat $C_{\mathrm{el}}/T$ diverges logarithmically, while immediately above $x_{\mathrm{crit}}$ the volume thermal expansion coefficient ${\alpha }_V/T$ and the Grüneisen ratio $\mathrm{\Gamma }={\alpha }_V/C_{\mathrm{el}}$ both diverge logarithmically in the low temperature limit, further indication of a ferromagnetic quantum critical point in ${\mathrm{Ni}}_{1-x}{\mathrm{Rh}}_x$.

The behavior of interacting spins subject to randomness is a longstanding issue and the emergence of exotic quantum states is among intriguing theoretical predictions. We show how a quantum-disordered phase emerges from a classical antiferromagnet by controlled randomness. ${}^1\mathrm{H}$ NMR of a successively x-ray-irradiated organic Mott insulator finds that the magnetic order collapses into a spin-glass-like state, immediately after a slight amount of disorder centers are created, and evolves to a gapless quantum-disordered state without spin freezing, spin gap, or critical slowing down, as reported by T. Furukawa et al. [Phys. Rev. Lett. 115, 077001 (2015)] through sequential reductions in the spin freezing temperature and moment.

We report strong terahertz ($\sim {10}^{12}\mathrm{Hz}$) high harmonic generation at room temperature in thin films of ${\mathrm{Cd}}_3{\mathrm{As}}_2$, a three-dimensional Dirac semimetal. Third harmonics are detectable with a tabletop light source and can be as strong as $100\mathrm{V/}\mathrm{cm}$ by applying a fundamental field of $6.5\mathrm{kV}/\mathrm{cm}$ inside the film, demonstrating an unprecedented efficiency for terahertz frequency conversion. Our time-resolved terahertz spectroscopy and calculations also clarify the microscopic mechanism of the nonlinearity originating in the coherent acceleration of Dirac electrons in momentum space. Our results provide clear insights for nonlinear currents of Dirac electrons driven by the terahertz field under the influence of scattering, paving the way toward novel devices for high-speed electronics and photonics based on topological semimetals.

The fine interplay between the simultaneous stretching and confinement of amyloid fibrils is probed by combining a microcapillary setup with atomic force microscopy. Single-molecule statistics reveal how the stretching of fibrils changed from force to confinement dominated at different length scales. System order, however, is solely ruled by confinement. Coarse-grained simulations support the results and display the potential to tailor system properties by tuning the two effects. These findings may further help shed light on in vivo amyloid fibril growth and transport in highly confined environments such as blood vessels.

We study a method to simulate quantum many-body dynamics of spin ensembles using measurement-based feedback. By performing a weak collective measurement on a large ensemble of two-level quantum systems and applying global rotations conditioned on the measurement outcome, one can simulate the dynamics of a mean-field quantum kicked top, a standard paradigm of quantum chaos. We analytically show that there exists a regime in which individual quantum trajectories adequately recover the classical limit, and show the transition between noisy quantum dynamics to full deterministic chaos described by classical Lyapunov exponents. We also analyze the effects of decoherence, and show that the proposed scheme represents a robust method to explore the emergence of chaos from complex quantum dynamics in a realistic experimental platform based on an atom-light interface.

In this Letter we discuss new soft theorems for the Goldstone-boson amplitudes with nonvanishing soft limits. The standard argument is that the nonlinearly realized shift symmetry leads to the vanishing of scattering amplitudes in the soft limit, known as the Adler zero. This statement involves certain assumptions of the absence of cubic vertices and the absence of linear terms in the transformations of fields. For theories which fail to satisfy these conditions, we derive a new soft theorem which involves certain linear combinations of lower point amplitudes, generalizing the Adler zero statement. We provide an explicit example of the $\mathrm{SU}(N)/\mathrm{SU}(N-1)$ sigma model which was also recently studied in the context of U(1) fibrated models. The soft theorem can be then used as an input into the modified soft recursion relations for the reconstruction of all tree-level amplitudes.

Polarized atomic beam sources have been in operation for many years to produce either nuclear polarized atomic hydrogen or deuterium beams. In recent experiments, such a source was used to polarize both isotopes independently at the same time. By recombination of the atoms, hydrogen-deuterium molecules with all possible nuclear spin combinations can be created. Those spin isomers are useful for further applications, like precision spectroscopy, as polarized targets for laser-particle acceleration, polarized fuel for fusion reactors, or as an option for future measurements of electric dipole moments.

A new regime in the interaction of a two-color ($\omega ,2\omega$) laser with a nanometer-scale foil is identified, resulting in the emission of extremely intense, isolated attosecond pulses—even in the case of multicycle lasers. For foils irradiated by lasers exceeding the blow-out field strength (i.e., capable of fully separating electrons from the ion background), the addition of a second harmonic field results in the stabilization of the foil up to the blow-out intensity. This is then followed by a sharp transition to transparency that essentially occurs in a single optical cycle. During the transition cycle, a dense, nanometer-scale electron bunch is accelerated to relativistic velocities and emits a single, strong attosecond pulse with a peak intensity approaching that of the laser field.

By using highly entangled states, quantum metrology guarantees a precision impossible with classical measurements. Unfortunately such states can be very susceptible to noise, and it is a great challenge of the field to maintain quantum advantage in realistic conditions. In this Letter we investigate the practicality of graph states for quantum metrology. Graph states are a natural resource for much of quantum information, and here we characterize their quantum Fisher information for an arbitrary graph state. We then construct families of graph states which approximately achieves the Heisenberg limit, we call these states bundled graph states. We demonstrate that bundled graph states maintain a quantum advantage after being subjected to independent and identically distributed dephasing or finite erasures. This shows that these graph states are good resources for robust quantum metrology. We also quantify the number of $n$ qubit stabilizer states that are useful as a resource for quantum metrology.

We analyze the dynamics of an initially trapped cloud of interacting quantum particles on a lattice under a linear (Stark) potential. We reveal a dichotomy: initially trapped interacting systems possess features typical of both many-body-localized and thermalizing systems. We consider both fermions ($t\text{−}V$ model) and bosons (Bose-Hubbard model). For the zero and infinite interaction limits, both systems are integrable: we provide analytic solutions in terms of the moments of the initial cloud shape and clarify how the recurrent dynamics (many-body Bloch oscillations) depends on the initial state. Away from the integrable points, we identify and explain the timescale at which Bloch oscillations decohere.

We use a near quantum limited detector to experimentally track individual quantum state trajectories of a driven qubit formed by the hybridization of a waveguide cavity and a transmon circuit. For each measured quantum coherent trajectory, we separately identify energy changes of the qubit as heat and work, and verify the first law of thermodynamics for an open quantum system. We further establish the consistency of these results by comparison with the master equation approach and the two-projective-measurement scheme, both for open and closed dynamics, with the help of a quantum feedback loop that compensates for the exchanged heat and effectively isolates the qubit.