Bell’s theorem shows that correlations created by a single entangled quantum state cannot be reproduced classically. Such correlations are called nonlocal. They are the elementary manifestation of a broader phenomenon called network nonlocality, where several entangled states shared in a network create network nonlocal correlations. In this Letter, we provide the first class of strategies producing nonlocal correlations in generic networks. In these strategies, called color matching (CM), any source takes a color at random or in superposition, where the colors are labels for a basis of the associated Hilbert space. A party (besides other things) checks if the color of neighboring sources match. We show that in a large class of networks without input, well-chosen quantum CM strategies result in nonlocal correlations that cannot be produced classically. For our construction, we introduce the graph theoretical concept of rigidity of classical strategies in networks, and using the Finner inequality, establish a deep connection between network nonlocality and graph theory. In particular, we establish a link between CM strategies and the graph coloring problem. This work is extended in a longer paper [M.-O. Renou, Phys. Rev. A 105, 022408 (2022)], where we introduce a second family of rigid strategies called token counting, leading to network nonlocality.

One-loop correction to the power spectrum in generic single-field inflation is calculated by using standard perturbation theory. Because of the enhancement inversely proportional to the observed red tilt of the spectral index of curvature perturbation, the correction turns out to be much larger than previously anticipated. As a result, the primordial non-Gaussianity must be much smaller than the current observational bound in order to warrant the validity of cosmological perturbation theory.

We show that ultradilute quantum liquids can be formed with ultracold bosonic dipolar atoms in a bilayer geometry. Contrary to previous realizations of ultradilute liquids, there is no need for stabilizing the system with an additional repulsive short-range potential. The advantage of the proposed system is that dipolar interactions on their own are sufficient for creation of a self-bound state and no additional short-range potential is needed for the stabilization. We perform quantum Monte Carlo simulations and find a rich ground-state phase diagram that contains quantum phase transitions between liquid, solid, atomic gas, and molecular gas phases. The stabilization mechanism of the liquid phase is consistent with the microscopic scenario in which the effective dimer-dimer attraction is balanced by an effective three-dimer repulsion. The equilibrium density of the liquid, which is extremely small, can be controlled by the interlayer distance. From the equation of state, we extract the spinodal density, below which the homogeneous system breaks into droplets. Our results offer a new example of a two-dimensional interacting dipolar liquid in a clean and highly controllable setup.

In relativistic magnetized plasmas, asymmetry in the number densities of left- and right-handed fermions, i.e., a nonzero chiral chemical potential ${\mu }_5$, leads to an electric current along the magnetic field. This causes a chiral dynamo instability for a uniform ${\mu }_5$, but our simulations reveal a dynamo even for fluctuating ${\mu }_5$ with zero mean. It produces magnetically dominated turbulence and generates mean magnetic fields via the magnetic $\alpha$ effect. Eventually, a universal scale-invariant $k^{-1}$ spectrum of ${\mu }_5$ and a $k^{-3}$ magnetic spectrum are formed independently of the initial condition.

In the magic-angle twisted bilayer graphene (MATBG), one of the most remarkable observations is the $C_3$-symmetry-breaking nematic state. We identify that the nematicity in MATBG is the $E$-symmetry ferro bond order, which is the modulation of correlated hopping integrals owing to the $E$-symmetry particle-hole pairing condensation. The nematicity in MATBG originates from prominent quantum interference among SU(4) $\text{valley}+\text{spin}$ composite fluctuations. This novel “$\text{valley}+\text{spin}$ fluctuation interference mechanism” is revealed by the density wave equation analysis for the realistic multiorbital Hubbard model for MATBG. We find that the nematic state is robust once three van Hove singularity points exist in each valley. This interference mechanism also causes novel time-reversal-symmetry-broken valley polarization accompanied by a charge loop current. We discuss interesting similarities and differences between MATBG and Fe-based superconductors.

We perform the first magnetohydrodynamic simulations in full general relativity of self-consistent rotating neutron stars (NSs) with ultrastrong mixed poloidal and toroidal magnetic fields. The initial uniformly rotating NS models are computed assuming perfect conductivity, stationarity, and axisymmetry. Although the specific geometry of the mixed field configuration can delay or accelerate the development of various instabilities known from analytic perturbative studies, all our models finally succumb to them. Differential rotation is developed spontaneously in the cores of our magnetars which, after sufficient time, is converted back to uniform rotation. The rapidly rotating magnetars show a significant amount of ejecta, which can be responsible for transient kilonova signatures. However, no highly collimated, helical magnetic fields or incipient jets, which are necessary for $\gamma$-ray bursts, arise at the poles of these magnetars by the time our simulations are terminated.

In this work, we perform a lattice QCD study of the intrinsic, rapidity-independent soft function within the framework of large momentum effective theory. The computation is carried out using a gauge ensemble of $N_f=2+1+1$ clover-improved twisted mass fermion. After applying an appropriate renormalization procedure and the removal of significant higher-twist contamination, we obtain the intrinsic soft function that is comparable to the one-loop perturbative result at large external momentum. The determination of the nonperturbative soft function from first principles is crucial to sharpen our understanding of the processes with small transverse momentum such as the Drell-Yan production and the semi-inclusive deep inelastic scattering. Additionally, we calculate the Collins-Soper evolution kernel using the quasi-transverse-momentum-dependent wave function as input.

We accomplish the complete two-loop computation of the leading-twist contribution to the photon-pion transition form factor $\gamma {\gamma }^{*}\to {\pi }^0$ by applying the hard-collinear factorization theorem together with modern multiloop techniques. The resulting predictions for the form factor indicate that the two-loop perturbative correction is numerically important. We also demonstrate that our results will play a key role in disentangling various models of the twist-two pion distribution amplitude thanks to the envisaged precision at Belle II.

Capturing non-Markovian dynamics of open quantum systems is generally a challenging problem, especially for strongly interacting many-body systems. In this Letter, we combine recently developed non-Markovian quantum state diffusion techniques with tensor network methods to address this challenge. As a first example, we explore a Hubbard-Holstein model with dissipative phonon modes, where this new approach allows us to quantitatively assess how correlations spread in the presence of non-Markovian dissipation in a 1D many-body system. We find regimes where correlation growth can be enhanced by these effects, offering new routes for dissipatively enhancing transport and correlation spreading, relevant for both solid state and cold atom experiments.

The elastic collective modes of a moiré superlattice arise not from vibrations of a rigid crystal but from the relative displacement between the constituent layers. Despite their similarity to acoustic phonons, these modes, called phasons, are not protected by any conservation law. Here, we show that disorder in the relative orientation between the layers and thermal fluctuations associated with their sliding motion degrade the propagation of sound in the moiré superlattice. Specifically, the phason modes become overdamped at low energies and acquire a finite gap, which displays a universal dependence on the twist-angle variance. Thus, twist-angle inhomogeneity is manifested not only in the noninteracting electronic structure of moiré systems, but also in their phononlike modes. More broadly, our results have important implications for the electronic properties of twisted moiré systems that are sensitive to the electron-phonon coupling.

Spin-charge conversion by the inverse spin Hall effect or inverse Rashba-Edelstein effect is prevalent in spintronics but dissipative. We propose a dissipationless spin-charge conversion mechanism by an excitonic pseudospin superfluid in an electron-hole double-layer system. Magnetic exchange fields lift singlet-triplet degeneracy of interlayer exciton levels in the double-layer system. Condensation of the singlet-triplet hybridized excitons breaks both a U(1) gauge symmetry and a pseudospin rotational symmetry around the fields, leading to spin-charge coupled superflow in the system. We demonstrate the mechanism by deriving spin-charge coupled Josephson equations for the excitonic superflow from a coupled quantum-dot model.

We show that bicircular light (BCL) is a versatile way to control magnetic symmetries and topology in materials. The electric field of BCL, which is a superposition of two circularly polarized light waves with frequencies that are integer multiples of each other, traces out a rose pattern in the polarization plane that can be chosen to break selective symmetries, including spatial inversion. Using a realistic low-energy model, we theoretically demonstrate that the three-dimensional Dirac semimetal ${\mathrm{Cd}}_3{\mathrm{As}}_2$ is a promising platform for BCL Floquet engineering. Without strain, BCL irradiation induces a transition to a noncentrosymmetric magnetic Weyl semimetal phase with tunable energy separation between the Weyl nodes. In the presence of strain, we predict the emergence of a magnetic topological crystalline insulator with exotic unpinned surface Dirac states that are protected by a combination of twofold rotation and time reversal $(2^{\prime })$ and can be controlled by light.

van der Waals materials possess an innate layer degree of freedom and thus are excellent candidates for exploring emergent two-dimensional ferroelectricity induced by interlayer translation. However, despite being theoretically predicted, experimental realization of this type of ferroelectricity is scarce at the current stage. Here, we demonstrate robust sliding ferroelectricity in semiconducting $1{\mathrm{T}}^{\prime }\text{−}{\mathrm{ReS}}_2$ multilayers via a combined study of theory and experiment. Room-temperature vertical ferroelectricity is observed in two-dimensional $1{\mathrm{T}}^{\prime }\text{−}{\mathrm{ReS}}_2$ with layer number $N\ge 2$. The electric polarization stems from the uncompensated charge transfer between layers and can be switched by interlayer sliding. For bilayer $1{\mathrm{T}}^{\prime }\text{−}{\mathrm{ReS}}_2$, the ferroelectric transition temperature is estimated to be $\sim 405\mathrm{K}$ from the second harmonic generation measurements. Our results highlight the importance of interlayer engineering in the realization of atomic-scale ferroelectricity.

Manipulating quantum thermal transport relies on uncovering the principle working cycles of quantum devices. Here we introduce the cycle flux ranking of network analysis to nonequilibrium thermal devices characterized as a quantum-transition network. To excavate the principal mechanism out of complex transport behaviors, we decompose the network into cycle trajectories, collect the cycle fluxes by algebraic graph theory, and select top-ranked cycle fluxes, i.e., the cycle trajectories with highest probabilities. We exemplify the cycle flux ranking in typical quantum device models, e.g., a thermal-drag spin-Seebeck pump and a quantum thermal transistor. Top-ranked cycle trajectories indeed elucidate the principal working mechanisms. Therefore, cycle flux ranking provides an alternative perspective that naturally describes the working cycle corresponding to the main functionality of quantum thermal devices, which would further guide the device optimization with desired performance.

Different extensions of the standard model of particle physics, such as braneworld or mirror matter models, predict the existence of a neutron sterile state, possibly as a dark matter candidate. This Letter reports a new experimental constraint on the probability $p$ for neutron conversion into a hidden neutron, set by the STEREO experiment at the high flux reactor of the Institut Laue-Langevin. The limit is $p<3.1\times {10}^{-11}$ at 95% C.L. improving the previous limit by a factor of 13. This result demonstrates that short-baseline neutrino experiments can be used as competitive passing-through-walls neutron experiments to search for hidden neutrons.

The trapping of a lower hybrid wave in the tokamak edge transport barrier is predicted, reducing by 3 orders of magnitude the excitation threshold for the absolute parametric decay instability that leads to side scattering of the ordinary microwave pump in electron cyclotron resonance heating (ECRH) experiments. This process is similar to the stimulated Raman scattering instability in laser physics and can result in substantial anomalous scattering of the pump wave, like in laser fusion experiments. The corresponding broadening of the ECRH power deposition profile can reduce the ability of this method to control the neoclassical tearing modes both in present day machines, as ASDEX-Upgrade, where the theory can be checked, and in fusion reactors such as ITER and DEMO.