Understanding quantum phases of matter is a fundamental goal in physics. For pure states, the representatives of phases are the ground states of locally interacting Hamiltonians, which are also renormalization fixed points (RFPs). These RFP states are exactly described by tensor networks. Extending this framework to mixed states, matrix product density operators (MPDOs) that are RFPs are believed to encapsulate mixed-state phases of matter in one dimension, where nontrivial topological phases have already been shown to exist. However, to better motivate the physical relevance of those states, and in particular the physical relevance of the recently found non trivial phases, it remains an open question whether such MPDO RFPs can be realized as steady states of local Lindbladians. In this work, we resolve this question by analytically constructing parent Lindbladians for MPDO RFPs. These Lindbladians are local, frustration free, and exhibit minimal steady-state degeneracy. Interestingly, we find that parent Lindbladians possess a rich structure that distinguishes them from their Hamiltonian counterparts. In particular, we uncover an intriguing connection between the noncommutativity of the Lindbladian terms and the fact that the corresponding MPDO RFP belongs to a nontrivial phase.

The quantum approximate optimization algorithm (QAOA) is a variational ansatz that resembles the Trotterized dynamics of a quantum annealing (QA) protocol. This work formalizes this connection formally and empirically, showing that the angles of a multilayer QAOA circuit converge to universal QA trajectories. Furthermore, the errors in both QAOA circuits and QA paths act as thermal excitations in pseudo-Boltzmann probability distributions whose temperature decreases with the invested resource—i.e., integrated angles or total time—and which in QAOA also contain a higher temperature arising from the Trotterization. This also means that QAOA and QA are cooling protocols and simulators of partition functions whose target temperature can be tuned by rescaling the universal trajectory. The average cooling power of both methods exhibits favorable algebraic scalings with respect to the target temperature and problem size, whereby in QAOA the coldest temperature is inversely proportional to the number of layers, $T\sim 1/p$, and to the integrated angles—or integrated interactions in QA.

Hybrid chiral-omega bianisotropic responses are challenging to achieve within a single metamaterial layer due to their distinct symmetry requirements. Here, we demonstrate that such hybrid response naturally emerges from mirror symmetry breaking in a single-layer trefoil knot-particle metasurface. A single geometric parameter, the offset of vertical interconnects between top and bottom faces, continuously tunes the response from pure chiral to hybrid chiral-omega behavior. Using dipole moment decomposition, we reveal that symmetry breaking activates the hybrid response by allowing coupling of current modes to orthogonal dipole moments, enabling simultaneous control over transmission and reflection asymmetries. Experimental measurements of complex-valued scattering coefficients validate the predicted hybrid response through direct susceptibility extraction. These results establish geometric symmetry engineering as a design principle for controlling electromagnetic coupling pathways in bianisotropic metamaterials.

We construct the first self-consistent framework for holographic thermodynamics in finite-cutoff holography, thereby capturing gravitational thermodynamics beyond the anti-de Sitter (AdS) boundary. We formulate two distinct first laws of thermodynamics: for the gravitational bulk, a Schwarzschild-AdS black hole with a finite Dirichlet cutoff, and for its dual $T^2$ deformed conformal field theory (CFT) on the boundary. The central innovation is promoting the deformation parameter to a thermodynamic variable on the boundary, which maps precisely to the cutoff radius in the bulk. We demonstrate exact duality between these two thermodynamic laws, establishing a complete holographic dictionary. This framework reveals that the $T^2$ deformation never lowers the confinement-deconfinement phase transition temperature below that of the original undeformed CFT, which acts as a global minimum. These results offer insights into gravitational thermodynamics with boundary constraints and quantum gravity in finite spacetime regions.

Free electron lasers (FELs) are powerful, tunable light sources capable of delivering ultrashort, coherent radiation over a wide spectral range, but their broad scientific and technological impact is limited by the size and cost of large-scale accelerators. Laser wakefield acceleration (LWFA) offers a compact alternative via the ultrahigh accelerating gradients, though achieving FEL gain with such beams remains a major challenge due to the stringent beam-quality requirements. Here, we present a successful demonstration of a laser-plasma accelerator-driven FEL operating at a central wavelength of $40\mathrm{nm}$ with a highly nonlinear gain. A compact $0.8\mathrm{J}$ laser system, combined with precise control over the plasma-density profile, injection conditions, and the stability of both laser wave front and gas jet, enabled the generation of high-quality monoenergetic electron beams with excellent shot-to-shot reproducibility. A comprehensive start-to-end simulation framework was established, incorporating beam acceleration, transport, and FEL generation. Each stage of the simulation shows good agreement with the experimental diagnostics. The resulting FEL radiation exhibits clear exponential gain of approximately 20 times. This work highlights a reliable route toward compact, tunable, x-ray FELs driven by LWFA, and represents a significant step toward practical applications of laser-plasma-based light sources.

We present a robust pulse optimization method for adiabatic population transfer and adiabatic quantum computation. The approach relies on identifying control pulses that keep the evolving quantum system close to its instantaneous ground state. By combining advanced gradient-free optimization tools with specialized cost functions for adiabatic control, it achieves both efficiency and robustness. To demonstrate its generality, we apply the method to three examples involving both atomic and superconducting qubits. We test different optimization cost functions and discretization bases, showing that the approach outperforms ensemble optimization. Finally, to verify its performance on real quantum hardware, we implement digitized adiabatic qubit control using the optimized pulses on the IBM quantum cloud.

Physical constraints and engineering challenges, including wafer dimensions, classical control cabling, and refrigeration volumes, impose significant limitations on the scalability of quantum computing units. As a result, a modular quantum computing architecture, comprising small processors interconnected by quantum links, is emerging as a promising approach to fault-tolerant quantum computing. However, the requirements that the network must fulfill to enable distributed quantum computation remain largely unexplored. We consider an architecture tailored for qubits with nearest-neighbor physical connectivity, leveraging the surface code for error correction and enabling fault-tolerant operations through lattice surgery and magic state distillation. We propose measurement teleportation as a tool to extend lattice surgery techniques to qubits located on different computing units interconnected via Bell pairs. Through memory simulations, we build an error model for logical operations and deduce an end-to-end resource estimation of Shor’s algorithm over a minimalist distributed architecture. Concretely, for a characteristic physical gate error rate of ${10}^{-3}$, a processor cycle time of 1 µs, factoring a 2048-bit RSA integer is shown to be possible with 379 computing processors, each made with 89 781 qubits, with negligible space and time overhead with respect to a monolithic approach without parallelization, if 70 Bell pairs are available per cycle time between each processor with a fidelity exceeding $98.1\%$.

Despite the successful demonstration of compact free-electron lasers (FELs) driven by laser wakefield accelerators (LWFAs), the inherent shot-to-shot fluctuations in LWFAs, including both laser and plasma instabilities, remain a primary obstacle to realizing LWFA-driven FELs with robust operation. Here, we present a conceptual design for LWFA-driven FELs with sufficient tolerance against shot-to-shot fluctuations using the covariance matrix adaptation evolution strategy. Start-to-end simulations demonstrated that this systematic optimization resulted in a significant improvement in the robustness of FELs. With the optimized configurations, the radiation energy can be maintained above $1\mu \mathrm{J}$ at a wavelength of approximately 25 nm, even when accounting for twice the root-mean-square ranges of these instabilities. This proposed scheme represents a substantial advancement in the development of compact LWFA-driven FEL systems, enabling robust operation and paving the way for the realization of reliable and widely accessible sources.

We study the interplay between strong correlations and Markovian dephasing, resulting from monitoring the charge or spin degrees of freedom of a quantum dot described by a dissipative Anderson impurity model. Using the auxiliary master equation approach, we compute the steady-state spectral function and occupation of the dot and discuss the role of dephasing on Kondo physics. Furthermore, we consider a two-lead setup that allows to compute the steady-state current and conductance. We show that the Kondo steady state is robust to moderate charge dephasing but not to spin dephasing, which we interpret in terms of dephasing-induced heating of low-energy excitations. Finally, we show universal scaling collapse of the nonlinear conductance with a dephasing-dependent Kondo scale.

Belief propagation (BP) is an efficient message-passing algorithm widely used for inference in graphical models and for solving various problems in statistical physics. However, BP often yields inaccurate estimates of order parameters and their susceptibilities in finite systems, particularly in sparse networks with few loops. Here, we show for both percolation and Ising models that fixing the state of a single well-connected “source” node to break global symmetry substantially improves inference accuracy and captures finite-size effects across a broad range of networks, especially treelike ones, at no additional computational cost.

The influences of restitution coefficient, $e_n$, interparticle friction, $\mu$, and size ratio, $R$, on gravity-driven percolation of fine particles through static beds of larger particles in the free-sifting regime ($R\gtrsim 6.5$) remain largely unexplored. Here, we use discrete element method simulations to study the fine particle percolation velocity, $v_p$, and velocity fluctuations, $v_{\mathrm{rms}}$, for $7\le R\le 50$ and a range of $e_n$ and $\mu$. Varying $e_n$ modulates the degree of particle excitation and thereby alters the nature of particle trajectories: at low $e_n$, percolation is dominated by gravity, whereas increasing $e_n$ amplifies velocity fluctuations thereby reducing the mean percolation velocity. Increasing $\mu$ decreases $v_{\mathrm{rms}}$ but its influence on $v_p$ varies with $v_{\mathrm{rms}}$, decreasing $v_p$ for low $v_{\mathrm{rms}}$ and increasing $v_p$ for high $v_{\mathrm{rms}}$. Although the influence of size ratio is weaker, larger values of $R$ increase both $v_p$ and $v_{\mathrm{rms}}$. We also assess the influence of different excitation mechanisms, specifically using static, randomly excited, and sheared beds, finding that an inverse correlation between $v_p$ and $v_{\mathrm{rms}}$ persists across all cases and is well-described by the Drude model, where increased scattering reduces mobility, when $v_{\mathrm{rms}}$ is large. However, for weakly excited particles with low $v_{\mathrm{rms}}$, the Drude analogy breaks down. In this regime, we introduce a staircase-inspired model that accounts for the gravitationally dominated percolation behavior. These findings provide fundamental insight into the mechanisms governing percolation dynamics in porous media and granular systems.

Machine learning is offering powerful tools for the development and discovery of reduced models of nonlinear, multiscale plasma dynamics from the data of first-principles kinetic simulations. However, ensuring the physical consistency of such models requires embedding fundamental symmetries of plasma dynamics. In this work, we explore a symmetry-embedding strategy based on data augmentation, where symmetry-preserving transformations (e.g., Lorentz and Galilean boosts) are applied to simulation data. Using both sparse regression and neural networks, we show that models trained on symmetry-augmented data more accurately infer the plasma fluid equations and pressure tensor closures from fully kinetic particle-in-cell simulations of magnetic reconnection. We show that this approach suppresses spurious inertial-frame-dependent correlations between dynamical variables, improves data efficiency, and significantly outperforms models trained without symmetry-augmented data, as well as commonly used theoretical pressure closure models. Our results establish symmetry-based data augmentation as a broadly applicable method for incorporating physical structure into machine-learned reduced plasma models.

We study the nonlinear and resonant process of two-photon ionization of atoms (He and H) in a pump-probe scheme. The pump pulse prepares the quantum system in a superposition of the ground state and an excited bound state. By varying the phase difference between the pulses, we show how it is possible to coherently control the dressed-state population during the probe pulse. Our main result is that for certain laser parameters, the control over the dressed-state population leads to strong control of the ionization probability during the probe pulse. The effect arises due to one of the dressed states becoming stabilized against ionization. Contrasting effects from circular and linear polarized pulses demonstrate how such “bound states in the continuum” are sensitive to the degeneracy of the coupled continuum.

Experimental realizations of spin models are irremediably prone to errors, which can propagate through the system corrupting experimental signals. We study how such errors affect the measurement of local observables in systems with long-range interactions, where perturbations can spread more rapidly. Specifically, we focus on the stability of thermal equilibrium and investigate its relation to the correlation structure of the system, both analytically and numerically. As a main result, we prove that the stability of local expectation values follows from the decay of correlations on the Gibbs state and the Lieb-Robinson bound. We also provide numerical evidence that this stability extends to an even larger regime of interacting long-range systems. Our results support the robustness of analog simulation platforms for long-range models and provide further evidence that computing physical quantities of interest can be significantly easier than performing arbitrary quantum computations.

$\mathrm{Cs}{\mathrm{V}}_3{\mathrm{Sb}}_5$ exhibits a unique double-dome superconducting phase diagram under pressure, closely linked to its distinctive charge density wave (CDW) order evolution and corresponding Fermi surface reconstruction. The intricate interplay between CDW and superconductivity has garnered significant research interest, particularly in finding experimental methods to investigate Fermi surface evolution under pressure. Here, by measuring the quantum oscillation signals in in-plane resistivity and thermoelectric effect of $\mathrm{Cs}{\mathrm{V}}_3{\mathrm{Sb}}_5$ at various pressures, we reveal for the first time that the Fermi surface of $\mathrm{Cs}{\mathrm{V}}_3{\mathrm{Sb}}_5$ undergoes an abrupt change around 0.4 GPa. This phenomenon may be associated with alterations in the interlayer modulation within the CDW state, which is consistent with our density functional theory calculations. Furthermore, we observe the presence of a Dirac band that may moves away from the Fermi energy as pressure increases. Our findings offer crucial insights into the Fermi surface evolution of $\mathrm{Cs}{\mathrm{V}}_3{\mathrm{Sb}}_5$ under pressure.