We calculate the two-loop heavy quarkonium Hamiltonian within potential-nonrelativistic-QCD effective field theory in the nonannihilation channel. This calculation represents the first nontrivial step toward determining the ${\mathrm{N}}^4\mathrm{LO}$ Hamiltonian in the weak coupling regime. The large amount of computation is systematically handled by employing the $\beta$ expansion, differential equations for master integrals, and adopting a single-step matching procedure, in contrast to the conventional two-step approach.

We present a novel resonance mode in capacitive radio frequency (rf) discharges in the presence of an oblique magnetic field at low pressures. We observe the self-excitation of high-frequency harmonics of the current in magnetized capacitive rf discharges through the magnetized plasma series resonance (MPSR) induced by applying a low-frequency power. Utilizing an equivalent circuit model, we reveal that these harmonics arise from the hybrid combination of the magnetic gyration of electrons and the PSR. When the MPSR occurs, the impedance of the series resonator system is at a minimum, resulting in the amplitude of higher harmonics being comparable to that of the fundamental frequency. The high-frequency harmonics with large amplitude cause strong oscillations in the electron heating rate, ultimately enhancing the total power dissipation. The presence of harmonics is suppressed by increasing the pressure due to collisional damping.

Quasi-one-dimensional (Q1D) systems are inherently unfavorable for superconductivity due to electronic instabilities and significant quantum fluctuations. This has led to a half-century-long pursuit of strong and robust Q1D superconductors. Herein, we propose an effective multiorbital chain approach that utilizes the interorbital self-doping to not only suppress the instability but also to position the Fermi level near the band edges. Crucially, the introduced multiorbital band crossings simultaneously create significant interband pairings that suppress pair fluctuations. As a result, strong and robust Q1D superconductivity becomes achievable. Our proposal is further realized in a realistic material system, namely, chainlike NaBe. Ab initio Eliashberg theory calculations predict a high superconducting transition temperature ($T_{\mathrm{C}}$) of 17.2 K in NaBe, owing to its significant interband pairings and band-edge effects. Under doping or pressure, the $T_{\mathrm{C}}$ is boosted to over 20 K, which greatly exceeds the record of 11.5 K of all known Q1D superconductors. This work paves the way for discovering strong and robust Q1D superconductors in the multiorbital BCS-Eliashberg frame.

Hydrogen hydrates exhibit a rich phase diagram influenced by both pressure and temperature, with the so-called ${\mathrm{C}}_2$ phase emerging prominently above 2.5 GPa. In this phase, hydrogen molecules are densely packed within a cubic icelike lattice and the interaction with the surrounding water molecules profoundly affects their quantum rotational dynamics. Herein, we delve into this intricate interplay by directly solving the Schrödinger’s equation for a quantum ${\mathrm{H}}_2$ rotor in the ${\mathrm{C}}_2$ crystal field at finite temperature, generated through density functional theory. Our calculations reveal a giant energy splitting relative to the magnetic quantum number of $\pm 3.2\mathrm{meV}$ for $l=1$. Employing inelastic neutron scattering, we experimentally measure the energy levels of ${\mathrm{H}}_2$ within the ${\mathrm{C}}_2$ phase at 6.0 and 3.4 GPa and low temperatures, finding good agreement with our theoretical predictions. These findings underscore the pivotal role of hydrogen-water interactions in dictating the rotational behavior of the hydrogen molecules within the ${\mathrm{C}}_2$ phase and indicate heightened van der Waals interactions compared to other hydrogen hydrates.

Designer heterostructures have offered a very powerful strategy to create exotic superconducting states by combining magnetism and superconductivity. In this Letter, we use a heterostructure platform combining supramolecular metal complexes (SMCs) with a quasi-2D van der Waals superconductor ${\mathrm{NbSe}}_2$. Our scanning tunneling microscopy measurements demonstrate the emergence of Yu-Shiba-Rusinov bands arising from the interaction between the SMC magnetism and the ${\mathrm{NbSe}}_2$ superconductivity. Using x-ray absorption spectroscopy and x-ray magnetic circular dichroism measurements, we show the presence of antiferromagnetic coupling between the SMC units. These result in the emergence of an unconventional $3\times 3$ reconstruction in the magnetic ground state that is directly reflected in real space modulation of the Yu-Shiba-Rusinov bands. The combination of flexible molecular building blocks, frustrated magnetic textures, and superconductivity in heterostructures establishes a fertile starting point to fabricating tunable quantum materials, including unconventional superconductors and quantum spin liquids.

It is well established that the long-range van der Waals or thermal Casimir interaction between two semi-infinite dielectrics separated by a distance $H$ is screened by an intervening electrolyte. Here we show how this interaction is modified when an electric field of strength $E$ is applied parallel to the dielectric boundaries, leading to a nonequilibrium steady state with a current. The presence of the field induces a long-range thermal repulsive interaction, scaling just like the thermal Casimir interaction between dielectrics without the intervening electrolyte, i.e., as $1/H^3$. At small $E$ the effect is of order $E^2$, while at large fields it saturates to an $E$ independent value. We explain the results in terms of a decoupling mechanism between the charge density fluctuations of cations and anions at large applied fields.

Cohesion can dramatically affect the flow of granular media. In this Letter, thanks to a cohesion-controlled granular material, we propose to investigate experimentally the effect of the cohesion on the discharge from a silo. We use two geometries, a cylindrical silo and a thin rectangular silo, with an adjustable bottom to control the size of the orifice. Similarly to cohesionless granular material, the mass flow rate is mostly controlled by the diameter of the outlet $D$, however, we observe that the cohesion tends to decrease the flow rate. We show that this effect is controlled by a cohesive length, based on the cohesive yield stress and gravity acceleration, which acts as an effective particle size. This cohesive length is also found to control the onset of flow.

We present a locomotion mechanism that uses the stick-slip transition of a soft passive structure with an internal mechanical resonance. The structure is harmonically driven by a global vertical shaking and, because of its resonance dephasing and the threshold response of stick-slip transition, it can either move forward or backward. We establish a relation for the motion acceleration threshold that we experimentally validate. We identify a nontrivial regime close to the resonance with a velocity inversion for a constant excitation frequency and an increasing driving amplitude. We finally show that we can achieve a controlled multimodal motion by combining multiple internal resonances.

Despite the fact that neural dynamics is triggered by discrete synaptic events, the neural response is usually obtained within the diffusion approximation representing the synaptic inputs as Gaussian noise. We derive a mean-field formalism encompassing synaptic shot noise for sparse balanced neural networks. For low (high) excitatory drive (inhibitory feedback) global oscillations emerge via continuous or hysteretic transitions, correctly predicted by our approach, but not from the diffusion approximation. At sufficiently low in-degrees the nature of these global oscillations changes from drift driven to cluster activation.

By braiding non-Abelian anyons it is possible to realize fault-tolerant quantum algorithms through the computation of Jones polynomials. So far, this has been an experimentally formidable task. In this Letter, a photonic quantum system employing two-photon correlations and nondissipative imaginary-time evolution is utilized to simulate two inequivalent braiding operations of Majorana zero modes. The resulting amplitudes are shown to be mathematically equivalent to Jones polynomials. The high fidelity of our optical platform allows us to distinguish between a wide range of links, such as Hopf links, Solomon links, Trefoil knots, Figure Eight knots and Borromean rings, through determining their corresponding Jones polynomials. Our photonic quantum simulator represents a significant step towards executing fault-tolerant quantum algorithms based on topological quantum encoding and manipulation.

It has been a long-standing goal to improve dispersive qubit readout with squeezed light. However, injected external squeezing (IES) cannot enable a practically interesting increase in the signal-to-noise ratio (SNR), and simultaneously, the increase of the SNR due to the use of intracavity squeezing (ICS) is even negligible. Here, we counterintuitively demonstrate that using IES and ICS together can lead to an exponential improvement of the SNR for any measurement time, corresponding to a measurement error reduced typically by many orders of magnitude. More remarkably, we find that in a short-time measurement, the SNR is even improved exponentially with twice the squeezing parameter. As a result, we predict a fast and high-fidelity readout. This work offers a promising path toward exploring squeezed light for dispersive qubit readout, with immediate applications in quantum error correction and fault-tolerant quantum computation.

We show that a non-Hermitian lattice with a disclination can host topological disclination states that are induced by on-site gain and loss. The disclination states are inherently non-Hermitian as they do not exist in the limit of zero gain or loss. They arise from charge fractionalization in the non-Hermitian lattice, which we establish using non-Hermitian Wilson loops calculated with biorthogonal products. The model is suitable for realization on established experimental platforms, such as arrays of photonic or polaritonic resonators. The emergence of the topological disclination states can manifest as an abrupt shift in emission intensity and frequency with varying gain or loss.

Photonic simulators are increasingly used to study physical systems for their affluent manipulable degrees of freedom. The advent of photonic chips offers a promising path towards compact and configurable simulators. Thin-film lithium niobate chips are particularly well suited for this purpose due to the high electro-optic coefficient, which allows for the creation of lattices in the frequency domain. Here, we fabricate and periodically modulate an on-chip resonator to observe band structures. The employed modulation rates are lower than the resonator linewidth, resulting in the inclusion of multiple lattice points within one resonant peak. This alleviates the difficulty of applying and detecting multiharmonic signals which are conventionally of ultrahigh frequency on chips and enables us to simulate structures with arbitrary-range coupling. As examples, we showcase the simulation of nanotubes along several directions where the required frequencies are reduced by more than 3 orders of magnitude (up to reduce near 100 GHz to around 10 MHz in our examples). Encompassing various models equipped with a gauge potential, our experiments demonstrate an effective and technically feasible scenario which may bolster the development of on-chip photonic simulators complementing existing techniques.

Static friction, a ubiquitous physical phenomenon, plays a significant role in natural processes and industrial applications. Its influence is particularly notable in the field of controlled micromanipulation and precision manufacturing, where static friction often exceeds kinetic friction and leads to material damage and unpredictable behaviors. In this study, we report the first experimental observation of the elimination of static friction peak in sliding micrometer contacts of layered materials, achieved through a technique involving selective etching of the amorphous edges of single crystalline surfaces. Our findings are consistent with theoretical models and simulations that predicted the absence of static friction between two atomically flat, pristine, weakly interacting, incommensurate solid surfaces. In this state, thermally induced spontaneous actuation in graphite homogeneous junctions was observed at temperatures slightly above room temperature (around $40°\mathrm{C}$), with contact sizes up to $100\mathrm{\mu }{\mathrm{m}}^2$. These results have significant implications for improving our understanding and control of static friction, opening up promising opportunities for the application of micromechanical devices and precision mechanical systems.

The nonintegrable higher spin Kitaev honeycomb model has an exact ${\mathbb{Z}}_2$ gauge structure, which exclusively identifies quantum spin liquid in the half-integer spin Kitaev model. But its constraints for the integer-spin Kitaev model are much limited, and even trivially gapped insulators cannot be excluded. The physical implications of exact ${\mathbb{Z}}_2$ gauge structure, especially ${\mathbb{Z}}_2$ fluxes, in integer-spin models remain largely unexplored. In this Letter, we theoretically show that a spin-$S$ Yao-Lee model [a spin-orbital model with SU(2) spin-rotation symmetry] possesses a topologically nontrivial quantum spin-orbital liquid ground state for any spin (both integer and half-integer spin) by constructing exact deconfined fermionic ${\mathbb{Z}}_2$ gauge charges. We further show that the conserved ${\mathbb{Z}}_2$ flux can also demonstrate the intriguing spin fractionalization phenomena in the non-Abelian topological order phase of the spin-1 Yao-Lee model. Its deconfined ${\mathbb{Z}}_2$ vortex excitation carries fractionalized spin-$\frac{1}{2}$ quantum number in the low-energy subspace, which is also a non-Abelian anyon. Our exact manifestation of spin fractionalization in an integer-spin model is rather rare in previous studies, and is absent in the Kitaev honeycomb model.

Nonlinear optics plays important roles in the research of fundamental physics and the applications of high-performance optoelectronic devices. The bulk nonlinear optical responses arise from the uniform light absorption in noncentrosymmetric crystals, and hence are usually considered to be the collective phenomena of all atoms. Here we show, in contrast to this common expectation, the nonlinear optical responses in antiferromagnets can be selectively accumulated near the surfaces, representing a skin effect. This is because the inversion symmetry, despite being broken globally by magnetism, is barely violated locally deeply inside these antiferromagnets. Using $A$-type layered antiferromagnets as the representatives, we predict that the spatial-dependent nonlinear optical responses, such as the bulk photovoltaic effect and second harmonic generation, are notable in the top- and bottommost layers and decay rapidly when moving away from the surfaces. Such a phenomenon is strongly associated with the antiferromagnetism and exists in a broad range of antiferromagnets composed of centrosymmetric sublattices, offering promising device applications using these antiferromagnets. Our work uncovers a previously overlooked property of nonlinear optical responses and opens new opportunities for high-performance antiferromagnetic optospintronics.

We consider an analytically tractable model that exhibits the main features of the Page curve characterizing the evolution of entanglement entropy during evaporation of a black hole. Our model is a gas of noninteracting fermions on a lattice that is released from a box into the vacuum. More precisely, our Hamiltonian is a tight-binding model with a defect at the junction between the filled box and the vacuum. In addition to the entanglement entropy we consider several other observables, such as the spatial density profile and current, and show that the semiclassical approach of generalized hydrodynamics provides a remarkably accurate description of the quantum dynamics including that of the entanglement entropy at all times $t$. Our hydrodynamic results agree closely with those obtained via exact microscopic numerics. We find that the growth of entanglement with time is linear and universal, i.e, independent of the details of the defect. The decay shows $1/t$ scaling for conformal defect while for nonconformal defects, it is slower. Our analytical results from hydrodynamics enables us to make predictions for long time behaviors of observables that are otherwise highly inaccessible computationally by exact microscopic numerics. Our study shows the power of the semiclassical approach and could be relevant for discussions on the resolution of the black hole information paradox.

We present a novel new way—called Schrödingerization—to simulate general (quantum and nonquantum) systems of linear ordinary and partial differential equations (PDEs) via quantum simulation. We introduce a new transform, referred to as the warped phase transformation, where any linear—including nonautonamous—system of ordinary or partial differential equation can be recast into a system of Schrödinger’s equations, in real time, in a straightforward way. This approach is not only applicable to PDEs for classical problems but is also useful for quantum problems, including the preparation of quantum ground states and Gibbs thermal states, the simulation of quantum states in random media in the semiclassical limit, simulation of Schrödinger’s equation in a bounded domain with artificial boundary conditions, and other non-Hermitian physics. This formulation is versatile enough to be applicable in a simple way to both digital quantum simulation as well as to analog quantum simulation, and using either qubits or continuous-variable quantum systems (qumodes).