Surface-specific vibrational spectroscopies revolutionized the study of charged interfaces, by sensitively probing water's response in the electric double layer (EDL) and correlating it with surface charge via models like Gouy-Chapman-Stern. The assumed one-to-one relationship between water's spectroscopic response and surface charge has been widely accepted without question. We hereby propose a theoretical experiment to evaluate this assumption. Interestingly, our findings reveal a non-one-to-one relationship between surface charge and spectroscopic response, exhibiting a fascinating dependence on surface topology.

Suppressing Floquet thermalization is an important goal in the field of Floquet engineering. Here, we propose a driving transparency mechanism to suppress the Floquet thermalization in periodically driven tilted lattices of interacting spinless fermions. By leveraging the interplay between the tilting and interaction, the system can be engineered to prevent direct energy absorption from the driving at particular frequencies. We analytically determine these driving transparency frequencies through the Floquet time-dependent perturbation theory. The system is near-integrable at the driving transparency frequencies. The suppression of thermalization by the driving transparency is demonstrated numerically by the violation of the Floquet eigenstate thermalization hypothesis, the retention of the initial state, and the logarithmic growth of entanglement entropy. Our work provides an intuitive way to suppress Floquet thermalization and offers an opportunity to engineer exotic nonequilibrium Floquet states in tilted lattice systems.

Recent investigations suggest that the discrete linear unitary group $U\left(N\right)$ can be represented by interlacing a finite sequence of diagonal phase operations with an intervening unitary operator. However, despite rigorous numerical justifications, no formal proof has been provided. Here, we show that elements of $U\left(N\right)$ can be decomposed into a sequence of $N$-parameter phases alternating with one-parameter propagators of a lattice Hamiltonian. The proof is based on building a Lie group by alternating these two operators and showing its completeness to represent $U\left(N\right)$ for a finite number of layers. This is numerically verified by using Haar random matrices as targets, showing a convergence for exactly $N$ layers. As a specific application, we propose an integrated all-optical logic gate device that performs OR, NAND, XOR, and XAND tasks within a lossless and passive optical circuit design.

Networks of coupled Kerr parametric oscillators (KPOs) hold promise for the realization of neuromorphic and quantum computation. Yet, their rich bifurcation structure remains poorly understood. Here, we employ secular perturbation theory to map the stability regions of these networks and identify the regime where the system can be mapped to an Ising model. Starting with two coupled KPOs, we show how the bifurcations arise from the competition between the global parametric drive and linear coupling between the KPOs. We then extend this framework to larger networks with all-to-all equal coupling, deriving analytical expressions for the full cascade of bifurcation transitions. In the thermodynamic limit, we find that these transitions become uniformly spaced, leading to a highly regular structure. Our results reveal the precise bounds under which KPO networks have an Ising-like solution space, and thus provide crucial guidance for their experimental implementation.

We propose an efficient method to numerically simulate the superradiant emission dynamics of large numbers of quantum emitters in ordered arrays in the presence of long-range dipole-dipole interactions mediated by the vacuum electromagnetic field. Using the spatial symmetries of the system, we rewrite the equations of motion in a collective spin basis and subsequently apply a higher-order cumulant expansion for the collective operators. By truncating the subradiant collective modes with a heavily suppressed decay rate and keeping only the effect from the radiating collective modes, we reduce the numerical complexity significantly. This allows to efficiently compute the dissipative dynamics of the observables of interest for linear and ring-shaped arrays of quantum emitters. In particular, we characterize the second-order intensity correlation function $g^{\left(2\right)}(\tau =0)$, which is challenging to compute for extended systems with traditional cumulant expansion methods.

Quantum optimization is emerging as a prominent candidate for exploiting the capabilities of near-term quantum devices. Many application-relevant optimization tasks require the inclusion of inequality constraints, usually handled by enlarging the Hilbert space through the addition of slack variables. This approach, however, requires significant additional resources especially when considering multiple constraints. Here, we study an alternative direct implementation of these constraints within the quantum approximate optimization algorithm, achieved using qudit-sum gates, and compare it to the slack variable method generalized to qudits. We benchmark these approaches on three paradigmatic optimization problems. We find that the direct implementation of the inequality penalties vastly outperforms the slack variables method, especially when studying real-world inspired problems with many constraints. Within the direct penalty implementation, a linear energy penalty for unfeasible states outperforms other investigated functional forms, such as the canonical quadratic penalty. The proposed approach may thus be an enabling step for approaching realistic industry-scale and fundamental science problems with large numbers of inequality constraints.

In this paper we derive the Landau-Fokker-Planck (LFP) equation for the energy distribution function of a nondegenerate hot electrons in bulk semiconductors with strong electron-electron (e-e) interaction by the screened Coulomb potential described by a static dielectric function (the effect of dynamic screening is also analyzed qualitatively). The e-e scattering rates are calculated quantum-mechanically using the first Born approximation. The LFP equation was derived employing two different approaches: (i) a direct general transformation of the integral Boltzmann scattering operator; (ii) using the Chapman-Kolmogorov integral equation (CKE) for conditional transition probability densities. The screened potential allows to avoid any ad hoc cutoff procedures for tackling the problem of the Coulomb divergence of the matrix element in the scattering probability rates. However, the screening at the same time brings to the theory another problem, namely, that increase of the screening strength changes the character of the e-e scattering when it eventually becomes strongly inelastic. This corresponds to large energy transfer between the scattering electrons, which in turn, prohibits in principle considering the electron scattering process as a diffusion in the energy space (the necessary condition for the LFP approximation). We show that the screening effect must be explicitly included into the kinetic theory to correctly address the above two problems, and the cases of a weak and a strong screening need to be analyzed in detail. The LFP approximation is physically justified only for a weak screening. The obtained screening function coincides with the Brooks-Herring screening function. We have established general relationships between the kinetic coefficients in the LFP operator obtained by the above two approaches. The explicit expressions for the dynamic friction and the diffusion coefficients in the energy space are also obtained. Although, both approaches lead to the same solutions, we demonstrate that the CKE method is more universal approach, and the obtained here general relationships can be applied for any other scattering mechanism, provided that the required conditions are satisfied. We discuss the necessary validity conditions for the LFP equation, and show that for typical physical situations, e.g., for high-energy photoexcitation of the carriers, the LFP equation can be used up to the densities $\sim {10}^{18}\mathrm{c}{\mathrm{m}}^{-3}$. However, for higher densities the screening energy becomes too large, which results in an increase of the minimum energy transfer in the scattering events, and the required for the LFP conditions are violated. In this case, one must use the integral e-e scattering operator, which we obtained in the form suitable for numerical solution. Dynamic screening extends the LFP validity range. As an example of the application of the LFP equation, we discuss the perovskite solar cells, which are characterized by relatively low and comparable energies of the optical and acoustic phonons, and the generated carrier densities of the order of ${10}^{18}\mathrm{c}{\mathrm{m}}^{-3}$. In this case, the LFP equation can be applied for each of these interactions (electron-phonon and the e-e scattering). This allows to find correct distribution function of the hot electrons, and calculate the electron power loss, to which the e-e scattering makes the direct contribution through the corresponding energy relaxation channel in the kinetic equation.

Numerical investigations of the ionization mechanisms in the high-temperature high-density gold plasma formed by a high-contrast high-intensity laser pulse interacting with gold foil are performed to investigate high-efficiency gold ion acceleration with few petawatt (PW)-level laser systems, aiming at producing $\gtrsim 10$ MeV/u gold beams required to serve as an alternative to the front end of a conventional heavy-ion accelerator complex such as an ion source, linac, and drift tube linac. Short-pulse high-intensity laser pulses with a peak intensity of a few times ${10}^{22}{\mathrm{Wcm}}^{-2}$, which is not strong enough to expel Au L-shell electrons by laser field ionization, are shown to sufficiently resistively heat up the target bulk temperature so that collisional ionization by electrons in the plasma can expel L-shell electrons. The resultant highly charged Au ions ($\sim +72\pm 4$) are exposed to the sheath field and accelerated to higher energies of $\sim 20$ MeV/u.

We present a quantum repeater protocol for distributing entanglement over long distances, where a dedicated communication stage enables trial rates not limited by the travel time between repeater nodes. To accomplish this, each node contains several qubits that can couple to one single-photon emitter. Photons from the emitters in neighboring nodes generate heralded entanglement between qubits in these nodes. The protocol leaves the emitters disentangled from the rest of the system immediately after emitting the photons, thus allowing them to be reused to entangle other qubits without waiting for the repeater link round-trip time. This time multiplexing increases the protocol trial rate by up to an order of magnitude. The protocol is then combined with conventional deterministic entanglement swapping and heralded entanglement purification to extend the entanglement distance and reduce the entanglement error, respectively. We perform a complete protocol analysis by considering all relevant error sources, such as initialization, two-qubit gate, and qubit measurement errors, as well as the exponential decoherence of the qubits with time. The latter is particularly important since we analyze the protocol performance for a broad range of experimental parameters and obtain secret key rates ranging from 1 to $1000\mathrm{Hz}$ at a distance of 1000 km. Our results suggest that it is important to reach a qubit memory coherence time of around 1 s, and two-qubit gate and measurement errors on the order of ${10}^{-3}$ to obtain reasonable secret key rates over distances longer than achievable with direct transmission. While this work focuses on optimizing secret key rates, the protocol can also be used for Einstein-Podolsky-Rosen pair generation and is thus also relevant for, e.g., distributed quantum computing.

Physical quantities with long lifetimes have both theoretical significance in the study of quantum many-body systems and practical implications for quantum technologies. In this manuscript, we investigate the roles played by topological defects in the construction of quasiconserved quantities, using as a prototypical example the Kramers-Wannier duality defect in a deformed one-dimensional quantum transverse-field Ising model. We construct the duality defect Hamiltonian in three different ways: half-chain Kramers-Wannier transformation, utilization of techniques in the Ising fusion category, and defect-modified weak integrability breaking deformation. The third method is also applicable for the study of generic integrable defects under weak integrability breaking deformations. We also work out the deformation of defect-modified higher charges in the model and study their slower decay behavior. Furthermore, we consider the corresponding duality defect twisted deformed Floquet transverse-field Ising model and investigate the stability of the isolated zero mode associated with the duality defect in the integrable Floquet Ising model, under such weak integrability breaking deformation.

Recent experiments have searched for evidence of the impact of noninertial motion on the entanglement of particles. The success of these endeavors has been hindered by the fact that such tests were performed within spatial scales that were only “local” when compared to the spatial scales over which the noninertial motion was taking place. We propose a Sagnac-like interferometer that, by challenging such bottlenecks, is able to achieve entangled states through a mechanism induced by the mechanical rotation of a photonic interferometer. The resulting states violate the Bell-Clauser-Horne-Shimony-Holt (Bell-CHSH) inequality all the way up to the Tsirelson bound, thus signaling strong quantum nonlocality. Furthermore, we show that the Bell-CHSH inequality remains violated even without using any form of postselection up to the value $1+\sqrt{2}$. Our results demonstrate that mechanical rotation can be thought of as resource for controlling quantum nonlocality with implications also for recent proposals for experiments that can probe the quantum nature of curved spacetimes and noninertial motion.

Freeze desalination is an emerging, membrane-free desalination method that utilizes the ion rejection phenomenon during the freezing of seawater, where salt ions tend to be rejected by ice. However, it requires the ion rejection rate to be higher than 98.2% to generate drinking water; i.e., at least 98.2% of the salt ions remain in the liquid phase. This poses a challenge for one-step seawater freezing due to the trapping of salt ions in ice. In this work, we first reveal that the ion rejection phenomenon is governed by the competition between two factors: ice growth and ion diffusion, which can be described by two characteristic timescales, ${\tau }_{\mathrm{ice}}$ and ${\tau }_{\mathrm{ion}}$, respectively. To enhance the ion rejection rate, the ratio ${\tau }_{\mathrm{ice}}/{\tau }_{\mathrm{ion}}$ should be increased. Based on this criterion, we propose a freeze desalination method by freezing flowing seawater, where ${\tau }_{\mathrm{ion}}$ is reduced due to the enhancement of the ion diffusivity caused by flow shear, to obtain potable water through a single cycle of seawater freezing with the ion rejection rate exceeding 98.2%. With additional temperature control, the productivity of drinking water can be further improved. The proposed freeze desalination method shows great potential for commercialization.

We investigate the quantum Hall effect in bilayer dice lattices with AA-BB-CC and AB-BC-CA stacking configurations, focusing on the interplay between flat band stability and band topology. For the aligned AA-BB-CC stacking, the system exhibits a narrow zero Hall conductivity plateau at the Dirac point and hybrid integer quantum Hall states $(n=\pm 2,\pm 4)$ in some energy regions, originating from the coexistence of spin, valley, and layer degeneracies. Additionally, the flat band generated by AA-BB-CC stacking is more easily destroyed. In contrast, the cyclic AB-BC-CA stacking displays irregular Hall conductivity due to complex band structures lacking complete flat bands. By tuning interlayer coupling strength $t_{\perp }$ and hopping parameter $\alpha$, the corresponding results show that the position of the Dirac point relative to the high-symmetry point in the Brillouin zone determines the appearance of the conductivity transitions. A mixed integer quantum Hall effect with $n$ = 2 and  = 4 appears for specific values of $\alpha$.

We introduce a comprehensive framework for no practical broadcasting, demonstrating that no linear map can simultaneously meet the conditions of sample efficiency, unitary covariance, permutation invariance, and classical consistency. This work establishes a rigorous theoretical foundation and provides an in-depth analysis of the employed techniques. In particular, we apply Schur-Weyl duality to provide a simplified alternative proof for the uniqueness of linear maps, referred to as the canonical virtual broadcasting map, that satisfy unitary covariance, permutation invariance, and classical consistency. The sample complexity of this canonical map is determined through semidefinite programming. Expanding beyond the 1-to-2 case, we derive the canonical form for 1-to-$N$ virtual broadcasting, analyze the sample complexity involved in its realization, and explore its connections with temporal quantum states and pseudodensity operators.

Basket weaving is a traditional craft used to create practical three-dimensional (3D) structures. While the geometry and aesthetics of baskets have received considerable attention, the underlying mechanics and modern engineering potential remain underexplored. This work shows that 3D woven structures offer similar stiffness yet substantially higher resilience than their nonwoven continuous counterparts. We explore corner topologies that serve as building blocks to convert two-dimensional woven sheets into 3D metamaterials that can carry compressive loads. Under small deformations, the woven corners exhibit axial stiffness similar to continuous structures because the woven ribbons are engaged with in-plane loads. Under large deformations, the woven corners can be compressed repeatedly without plastic damage because ribbons can undergo elastic local buckling. We present a modular platform to assemble woven corners into complex spatial metamaterials and demonstrate applications including damage-resilient robotic systems and metasurfaces with tailorable deformation modes. Our results explain the historic appeal of basket weaving, where readily available ribbons are crafted into 3D structures with comparable stiffness yet far superior resilience to continuous systems. The modular assembly of woven metamaterials can further revolutionize design of next-generation automotive components, consumer devices, soft robots, and more where both resilience and stiffness are essential.

We propose a universal set of single- and two-qubit quantum gates acting on a hybrid qubit formed by coupling a quantum dot spin qubit to a ${\mathbb{Z}}_{2m}$ parafermion qubit with arbitrary integer $m$. The special case $m=1$ reproduces the results previously derived for Majorana qubits. Our formalism utilizes Fock parafermions, facilitating a transparent treatment of hybrid parafermion-spin systems. Furthermore, we highlight the previously overlooked importance of particle-hole symmetry in these systems. We give concrete examples how the hybrid qubit system could be realized experimentally for ${\mathbb{Z}}_4$ and ${\mathbb{Z}}_6$ parafermions. In addition, we discuss a simple readout scheme for the fractional parafermion charge via the measurement of the spin-qubit resonant frequency.

Accurate and precise quantum control is crucial for quantum information processing. Zero-area pulse control, originally developed for closed systems, has played a significant role in driving quantum systems toward desired states. However, its effectiveness is often compromised by environmental noise. Traditional methods can find optimal pulses for fixed environmental parameters, and they need to be recalculated again once the environmental parameters change. Here, we propose a supervised learning (SL)-based protocol to design optimal zero-area pulses in noisy environments. By including environmental parameters as input during training, the neural network (NN) learns to generate effective controls for various environmental parameters. We demonstrate the protocol using quantum state transmission through a spin chain governed by a non-Markovian master equation. The SL-optimized pulses significantly enhance transmission fidelity compared to ideal pulses, with greater improvements observed at higher system-bath coupling and temperature, where more optimization space exists. Interestingly, fidelity first increases and then decreases with stronger Markovianity, suggesting that highly Markovian environments limit control performance. We also compare the SL method with a genetic algorithm, and the similar results confirm the accuracy and generalization ability of the NN-based approach.

The statistical properties of space and astrophysical environments often exhibit heavy-tailed distributions, reflecting deviations from thermal equilibrium. These distributions can often be represented as a superposition of statistics, i.e., superstatistics. However, the heavy-tailed nature of these distributions can lead to significant nonphysical contributions from unrealistic superluminal particles, thereby biasing thermodynamic properties and the overall dynamics. In this work, we first quantify these unphysical effects for key thermodynamic quantities, like pressure and entropy, within the three universality classes of superstatistics, and we discuss a regularized formulation that resolves the issue without requiring a fully relativistic treatment. We then develop a relativistic extension of superstatistics by generalizing the Maxwell-Jüttner distribution to nonequilibrium settings. We derive the thermodynamic properties of the resulting distributions and analyze their asymptotic behavior in the weakly relativistic and ultrarelativistic limits. Finally, we apply our model to observational data of solar energetic protons and show that it provides an excellent fit, demonstrating its relevance for describing the statistical properties of high-energy astrophysical systems.

We derive an effective equation of motion for binary Bose mixtures, which generalizes the Cahn-Hilliard description of classical binary fluids to superfluid systems. Within this approach, based on a microscopic Hamiltonian formulation, we show that the domain growth law $L\left(t\right)\sim t^{2/3}$ observed in superfluid mixtures is not driven by hydrodynamic flows, but arises from the competition between interactions and quantum pressure. The effective theory allows us to derive key properties of superfluid coarsening, including domain growth and Porod’s laws. This provides a new theoretical framework for understanding phase separation in superfluid mixtures.