Direct numerical simulation of three-dimensional acoustic turbulence has been performed for both weak and strong regimes. Within the weak turbulence, we demonstrate the existence of the Zakharov-Sagdeev spectrum $\propto k^{-3/2}$ not only for weak dispersion but in the nondispersion (ND) case as well. Such spectra in the $k$ space are accompanied by jets in the form of narrow cones. These distributions are realized due to small nonlinearity compared with both dispersion or diffraction. Increasing pumping in the ND case due to dominant nonlinear effects leads to the formation of shocks. As a result, the acoustic turbulence turns into an ensemble of random shocks with the Kadomtsev-Petviashvili spectrum.

Macroscopic systems present particle-type solutions. Spontaneous symmetry-breaking can cause these solutions to travel in different directions, and the inclusion of random fluctuations can induce them to run and tumble. We investigate the running and tumbling of localized structures observed on a prototype model of one-dimensional pattern formation with noise. Statistically, the dynamics of localized structures are examined, particularly the mean square displacement as a function of time. It initially shows a diffusive behavior, replaced by a ballistic one, and finally manifests itself as diffusive again. We derive a minimal model for the position and velocity of localized structures, which reveals the origin of the observed dynamics.

Following the groundbreaking discovery of the ferroelectric nematic liquid crystal phase (${\mathrm{N}}_{\mathrm{F}}$), a series of closely-related new polar phases have also been found. An especially interesting one is the ferroelectric smectic A phase (${\mathrm{SmA}}_{\mathrm{F}}$) with spontaneous polarization along the layer normal observed in a few materials of the ${\mathrm{N}}_{\mathrm{F}}$ realm. Here, we present a mean-field molecular model that successfully captures the rich phase diagrams experimentally observed in the literature in terms of two parameters. Additionally, we carry out second harmonic generation, X-ray diffraction, and birefringence measurements in a compound exhibiting the ${\mathrm{SmA}}_{\mathrm{F}}$ phase to determine the appropriate order parameters and compare with the model predictions.

Quantum theory is traditionally formulated using complex numbers. This imaginarity of quantum theory has been quantified as a resource with applications in discrimination tasks, pseudorandomness generation, and quantum metrology. In the standard formulation, a quantum state is said to have “imaginarity” if the associated density matrix is not real-valued in a given, fixed basis. If instead we consider a set of states, it is possible to devise tests that guarantee imaginarity of some state in the set, independently of the basis chosen. Here we propose such basis-independent witnesses for imaginarity that rely on measurements of unitary-invariant properties of sets of states. For three pure states, we completely characterize the invariant values attainable by quantum theory, and give a partial characterization for four pure states. We show that simple pairwise overlap measurements suffice to witness imaginarity of sets of four states, but not for sets of three. Our witnesses are experimentally friendly, opening up a new path for measuring and using imaginarity as a resource.

Quantum incompatibility, referred as the phenomenon that some quantum measurements cannot be performed simultaneously, is necessary for various quantum information processing tasks, such as nonlocality and steering. When these applications come to high-dimensional multimeasurement scenarios, it is crucial and challenging to witness the incompatibility of measurements with complex structures. To address this problem, we propose a modified quantum state discrimination protocol that decomposes complex compatibility structures into pairwise ones and employs noise robustness to bound incompatibility structures. We then derive arithmetic bounds for arbitrary measurements and analytical bounds for mutually unbiased bases, and capture some quantum incompatibility structures where measurements are partly compatible and partly incompatible. Finally, we experimentally demonstrate our results and connect them with quantum steering, quantum simulability and quantum communications.

Quantum scars are special eigenstates of many-body systems that evade thermalization. They were first discovered in the PXP model, a well-known effective description of Rydberg atom arrays. Despite significant theoretical efforts, the fundamental origin of PXP scars remains elusive. By investigating the discretized dynamics of the PXP model as a function of the Trotter step $\tau$, we uncover a remarkable correspondence between the zero- and two-particle eigenstates of the integrable Floquet-PXP cellular automaton at $\tau =\pi /2$ and the PXP many-body scars of the time-continuous limit. Specifically, we demonstrate that PXP scars are adiabatically connected to the eigenstates of the $\tau =\pi /2$ Floquet operator. Building on this result, we propose a protocol for achieving high-fidelity preparation of PXP scars in Rydberg atom experiments.

We numerically construct stationary, rotating black binaries in general relativity with a positive cosmological constant. We consider identical black holes with either aligned or anti-aligned spins. Both cases have less entropy than the corresponding single Kerr–Schwarzschild–de Sitter black hole with the same total angular momentum and cosmological horizon entropy. Our solutions establish continuous nonuniqueness in general relativity without matter. They also provide initial data for the spinning binary merger problem (when orbital angular momentum is added).

The phenomena of dark matter and the baryon asymmetry pose two of the most pressing questions in today’s fundamental physics. Conversion-driven freeze-out has emerged as a successful mechanism to generate the observed dark matter relic density. It supports thermalization of dark matter despite its very weak couplings, aligning with the null results from direct and indirect detection experiments. In this Letter, we demonstrate that the departure from equilibrium of dark matter, induced by semi-efficient conversions, satisfies Sakharov’s conditions, providing a novel explanation for both dark matter and the baryon asymmetry. Specifically, for a leptophilic model, we establish the mechanism of conversion-driven leptogenesis. The scenario predicts dark matter masses close to the electroweak scale offering testable predictions, such as soft displaced leptons at the LHC and future colliders.

Many-body localization (MBL) hinders the thermalization of quantum many-body systems in the presence of strong disorder. In this Letter, we study the MBL regime in bond-disordered spin-$1/2$ XXZ spin chain, finding the multimodal distribution of entanglement entropy in eigenstates, sub-Poissonian level statistics, and revealing a relation between operators and initial states required for examining the breakdown of thermalization in the time evolution of the system. We employ a real space renormalization group scheme to identify these phenomenological features of the MBL regime that extend beyond the standard picture of local integrals of motion relevant for systems with disorder coupled to on-site operators. Our results pave the way for experimental probing of MBL in bond-disordered spin chains.

We perform infrared magnetospectroscopy of Landau level (LL) transitions in dual-gated bilayer graphene. At $\nu =4$ when the zeroth LL (octet) is filled, two resonances are observed indicating the opening of a gap. At $\nu =0$ when the octet is half-filled, multiple resonances disperse nonmonotonically with increasing displacement field, $D$, perpendicular to the sheet, showing a phase transition at modest displacement fields from a canted antiferromagnet (CAFM) to the layer-polarized state, with a gap that opens linearly in $D$. When $D=0$ and $\nu$ is varied, resonances at $\pm \nu$ show an electron-hole asymmetry with multiple line splittings as the octet is progressively filled. The $\nu =4$ data show good agreement with predictions from a mean-field Hartree-Fock calculation when accounting for multiple tight-binding terms in a four-band model of bilayer graphene. However, even by incorporating a valley interaction anisotropy tuned to the CAFM ground state, only partial agreement is found at $\nu =0$. Our results suggest additional physics is required to understand bilayer graphene at half-filling.

Information propagation in the one-dimensional infinite temperature Hubbard model with a dissipative particle sink at the end of a semi-infinite chain is studied. In the strongly interacting limit, the two-site mutual information and the operator entanglement entropy exhibit a rich structure with two propagating information fronts and superimposed interference fringes. A classical reversible cellular automaton model quantitatively captures the transport and the slow, classical part of the correlations but fails to describe the rapidly propagating information jet. The fast quantum jet resembles coherent free particle propagation, with the accompanying long-ranged interference fringes that are exponentially damped by short-ranged spin correlations in the many-body background.

The primary challenge in advancing practical quantum technology is the presence of noise, which can lead to decoherence and undermine the advantages of quantum systems. However, it is worth noting that noise can also contain information that can be harnessed to improve performance in certain quantum information tasks. This has been explored for specific types of noise, but the full potential of informative noise within general dynamics remains largely unknown. Here we demonstrate that informative noise can be transformed into a valuable resource for enhancing precision limits in quantum metrology. We provide necessary and sufficient conditions under which the precision achieved in the presence of informative noise can attain Heisenberg scaling. Our research offers a fresh perspective on the role of noise in quantum metrology and opens up avenues for achieving higher precision beyond the previously anticipated ultimate limit.

Rapidly stripping off multiple electrons from the target and triggering complete fragmentation with each constituent atom being charged up are ideal prerequisites for Coulomb explosion imaging. Here, we demonstrate that highly charged ion beam with energy in the Bragg peak region is a powerful tool capable of meeting these requirements. Using the $112.5\mathrm{keV}/\mathrm{u}$ ${\mathrm{C}}^{5+}$ beam, we successfully imaged the structures of pyridazine, pyrimidine, and pyrazine, three isomers of ${\mathrm{C}}_4{\mathrm{H}}_4{\mathrm{N}}_2$, by detecting ionic fragments ${\mathrm{H}}^{+}$, ${\mathrm{C}}^{2+}$, ${\mathrm{C}}^{+}$, and ${\mathrm{N}}^{+}$ in quadruple coincidence. The three isomers are unambiguously distinguished in the spectra of angular correlation between different fragments, and their structures are clearly visualized in momentum images. More importantly, taking the advantage of fast colliding interaction that creates high charge states on a subfemtosecond timescale, our approach effectively suppresses the distortion of molecular configuration during explosion, ensuring the high accuracy in structural imaging. This is confirmed by the quantitative agreement of momentum magnitudes between the point-charge model and the experiment for all fragments including hydrogen. Our work demonstrates that highly charged ion induced Coulomb explosion is a powerful tool for precisely imaging the initial structures of complex molecules.

The quantum valley Hall effect (QVHE) is characterized by the valley Chern number (VCN) in a way that one-dimensional (1D) chiral metallic states are guaranteed to appear at the domain walls (DW) between two domains with opposite VCN for a given valley. Although in the case of QVHE, the total Berry curvature (BC) of the system is zero, the BC distributed locally around each valley makes the VCN well defined as long as intervalley scattering is negligible. Here, we propose a new type of valley-dependent topological phenomenon that occurs when the BC is strictly zero at each momentum. Such zero Berry curvature (ZBC) QVHE is characterized by the valley Euler number (VEN) which is computed by integrating the Euler curvature around a given valley in two-dimensional (2D) systems with space-time inversion symmetry. 1D helical metallic states can be topologically protected at the DW between two domains with the opposite VENs when the DW configuration preserves either the mirror symmetry with respect to the DW or the combination of the DW space-time inversion and chiral symmetries. We establish the fundamental origin of ZBC QVHE. Also, by combining tight-binding model study and first-principles calculations, we propose stacked hexagonal bilayer lattices including $h$-BX ($X=\mathrm{As}$, P) and large-angle twisted bilayer graphenes as candidate systems with robust helical DW states protected by VEN.

We study the Kondo lattice model of multipolar magnetic moments interacting with conduction electrons on a triangular lattice. Bond-dependent electron hoppings induce a compasslike anisotropy in the effective Ruderman-Kittel-Kasuya-Yosida interaction between multipolar moments. This unique anisotropy stabilizes multipolar skyrmion crystals at zero magnetic field. In a unit cell, the skyrmion fractionalizes into meron composites subject to the conservation of total topological charge. Diverse multipolar phases in the phase diagram give rise to novel spontaneous Hall response of conduction electrons.

Stacking nonpolar, monolayer materials has emerged as an effective strategy to harvest ferroelectricity in two-dimensional (2D) van der Waals (vdW) materials. At a particular stacking sequence, interlayer charge transfer allows for the generation of out-of-plane dipole components, and the polarization magnitude and direction can be altered by an interlayer sliding. In this work, we use ab initio calculations and demonstrate that in prototype sliding ferroelectrics rhombohedrally-stacked bilayer transition metal dichalcogenides ${\mathrm{MoS}}_2$, the out-of-plane electric polarization can be robustly tuned by photoexcitation in a large range for a given sliding. Such tuning is associated with both a structural origin—i.e., photoinduced structural distortion—and a charge origin, namely, the distribution of photoexcited carriers. We elucidate different roles that photoexcitation plays in modulating sliding ferroelectricity under different light intensities, and we highlight the pivotal role of light in manipulating polarization of 2D vdW materials.