Variational quantum algorithms are often hindered by rugged optimization landscapes. In this work, we investigate the low-weight Pauli propagation (LWPP) algorithm and find that it serves as an unreliable energy estimator for variational circuits. However, we reveal a counterintuitive insight: The Pauli-weight truncation acts as a spectral filter, effectively smoothing out high-frequency local minima while preserving the global basin of attraction in the landscape. We identify this mechanism as landscape alignment, where the approximate landscape becomes a superior navigator compared to the rugged exact landscape. Benchmarks across diverse spin models and molecular systems demonstrate that LWPP-initialized optimization yields order-of-magnitude improvements in accuracy, often finding solutions inaccessible to direct exact optimization. This work reframes LWPP from a flawed simulator into a vital preoptimizer that serves not only as a cheap classical substitute but also as an essential tool for addressing quantum optimization challenges.

The effective Flory-Huggins parameter ${\chi }_e$ is one of the most important characteristics of any multicomponent polymer system. This parameter characterizes the free energy of interaction between monomers of different types and controls the phase behavior of polymer mixtures. In this work, we developed a perturbation theory and derived how ${\chi }_e$ depends on the details of an arbitrary coarse-grained polymer model. After defining ${\chi }_e$ in this way, we found that the models of symmetric polymer blends and diblock copolymer melts behaved universally: Their phase transition points, free energies, and mesoscopic invariant structure factors depended solely on the chain architecture, the invariant chain length $\overline{N}$, and the interaction parameter ${\chi }_{e}N$. To parametrize our perturbative expression for ${\chi }_e$, only the effective coordination number distribution in a reference homogeneous system needs to be measured. This distribution, in turn, can be directly mapped onto coarse-grained model parameters set prior to simulation, which clarifies how model construction influences ${\chi }_e$. Our definition of ${\chi }_e$ enables straightforward quantitative comparison of models with each other and with experiments, which will facilitate the computational design of multicomponent polymer materials.

We show that adding quadratic temporal dispersion to a dynamic-vacuum acoustic model yields a fully analytic, exactly isospectral mapping to the hydrogenic Coulomb problem. In the regime $\omega =D{q}^2$ with $D=\hslash /\left(2m_{\mathrm{eff}}\right)$, a proton-imprinted constitutive profile produces an inverse sound speed $1/c_s^2\left(r\right)=A\left(\omega \right)+C\left(\omega \right)/r$ and hence a time-harmonic operator $({\nabla }^2+k_{\mathrm{eff}}^2)$ that is Coulombic at each bound eigenfrequency. Separation of variables yields the exact hydrogenic eigenfunctions $R_{n\ell }\left(r\right)Y_{\ell }^m(\theta ,\varphi )$; the angular labels $(\ell ,m)$ emerge naturally from the Laplace-Beltrami spectrum on ${\mathbb{S}}^2$ via rotational symmetry and boundary conditions (as in standard quantum mechanics), while localization follows from $A\left({\omega }_n\right)<0$ in a reactive stop band consistent with causal, passive dispersion. While angular-momentum quantization follows directly from rotational symmetry and boundary conditions in standard quantum mechanics (consistent with Noether's theorem), here it emerges within a classical-like dispersive acoustic framework without introducing additional wave-mechanical postulates beyond symmetry and self-adjointness. This highlights dispersion's role in bridging a hydrodynamic description to quantumlike spectral structure. Identifying $q_n\equiv {\kappa }_n$ maps spatial scale to frequency, giving ${\omega }_n=D{\kappa }_n^2\propto 1/n^2$ and reproducing the Rydberg ladder. Calibration to the reduced-mass Rydberg frequency (${\omega }_{*}=2\pi c{R}_H$) fixes $D=\hslash /\left(2\mu \right)$ and $m_{\mathrm{eff}}=\mu$, with no free parameters. We determine the frequency dependence of $A\left({\omega }_n\right)$ and $C\left({\omega }_n\right)$ consistent with the underlying dispersive physics and demonstrate agreement with hydrogenic mode shapes and transition lines. The framework also predicts isotope shifts $[\mu \to \mu (M\left)\right]$ and symmetry-respecting Stark/Zeeman analogues. Dispersion thus renders quantization an emergent consequence of symmetry, boundary conditions, and causal response in a dynamic vacuum.

Anyons are quasiparticles with fractional charge and statistics that arise in strongly correlated two-dimensional systems such as the fractional quantum Hall effect and fractional Chern insulators. Interactions between anyons can lead to emergent phenomena, such as anyon superconductivity as well as anyon condensation that allows for a hierarchical construction of quantum Hall states. In this work, we study how quasihole anyons in a $\nu =1/3$ Laughlin fractional quantum Hall state can be bound together by a sufficiently strong attractive impurity potential. The competition between the repulsive interaction between the quasiholes themselves and the attractive interaction between the quasiholes and the impurity leads to states with different numbers of quasiholes bound to the impurity. Tuning the chemical potential via gating while remaining within a quantum Hall plateau changes the number of quasiholes bound to the impurity. We propose methods for studying these states experimentally, for example, using scanning tunneling microscopy and exciton spectroscopy. While the impurities in traditional platforms such as GaAs heterostructures are typically too weak to observe the binding of anyons, the recently discovered zero-field fractional Chern insulators in twisted ${\mathrm{MoTe}}_2$ offer a platform that may realize the strong-impurity regime.

In this work, we put forward the inclusion of error mitigation routines in the process of training variational quantum circuit (VQC) models. In detail, we define a real-time quantum error mitigation (RTQEM) algorithm to assist in fitting functions on quantum chips with VQCs. While state-of-the-art QEM methods cannot address the exponential loss concentration induced by noise in current devices, we demonstrate that our RTQEM routine can enhance VQCs’ trainability by reducing the corruption of the loss function. We tested the algorithm by simulating and deploying the fit of a monodimensional $u$-quark parton distribution function on a superconducting single-qubit device, and we further analyzed the scalability of the proposed technique by simulating a multidimensional fit with up to eight qubits.

Motivated by recent claims, we revisit how coherent perfect absorption (CPA) influences cavity and polaritonic linewidths. Using standard input-output theory and measurements on single-port bare microwave cavities and cavity-magnon hybrids, we find that CPA drives the on-resonance reflection amplitude to zero while the spectral width remains set by the total decay rate. Apparent narrowing observed near CPA is found to be a visual artifact that does not remain upon quantitative analysis. Extending the analysis to cavity magnomechanics, we show that logarithmic plots can exhibit apparent polaromechanical “normal-mode splitting,” whereas linear-scale spectra display no true splitting. These results clarify when CPA modifies amplitudes versus spectral poles, offer practical guidance for data presentation, and indicate that CPA alone is not a route to linewidth suppression or polaromechanical mode splitting in the linear, weak-probe regime.

We show that Jacobson's thermodynamic derivation of Einstein's equations remains valid when local Rindler horizons are modeled as finite heat-capacity systems, resolving the infinite-bath assumption of Unruh thermodynamics. The horizon entropy then takes the form of Rényi entropy with nonextensivity parameter $\lambda \sim C^{-1}$, or equivalently an “Einstein entropy” that uniquely preserves Einstein's equations for arbitrary $C$. In both cases, the Unruh temperature is modified to $T_{\text{mod}}=\frac{\hslash \kappa }{2\pi }\left(1+\frac{S}{C}\right)$, establishing a universal link between finite-capacity thermodynamics and generalized entropies. We further derive a corrected scalar Einstein equation with an upper bound on horizon energy flux, suggesting testable signatures in heavy-ion collisions, spin-polarization experiments, and analog gravity, emergent gravity.

Coupling of oscillators is a universal phenomenon observed across diverse fields, from power grids in engineering to neuronal oscillators and circadian rhythms in biology. Understanding their dynamics requires identifying how individual oscillators interact. Traditionally, inferring the coupling mechanism from observable time series data involves estimating the coupling function—describing the interaction mechanism—using preassigned basis functions such as trigonometric polynomials. However, this approach is limited by the lack of a definitive rule for selecting the optimal number of basis functions, relying instead on subjective user choices. Here, we found that no single optimal number of basis functions exists: While using more basis functions helps capture complex coupling mechanisms, it tends to overfit and degrade performance with sparse or noisy data. To overcome these limitations, we developed Inference of Coupling using physics-informed neural networks (IC-PINN). Unlike conventional approaches, IC-PINN can infer diverse coupling functions from sparse and noisy data without requiring manual tuning, making it broadly applicable to various real-world systems of coupled oscillators. IC-PINN successfully identified that the segmentation clock operates via a “Winner-Take-All” synchronization mechanism and accurately inferred the coupling function in the self-assembly of optically interacting nanorotors. By offering a powerful tool for studying coupled oscillators, IC-PINN can provide deeper insights into complex interacting systems across biology, physics, and beyond.

We report a giant enhancement of circular photogalvanic effect (CPGE) in the oxide two-dimensional electron gas at ${\mathrm{LaAlO}}_3/{\mathrm{SrTiO}}_3$ and $\mathrm{LaAl}{\mathrm{O}}_3/\mathrm{KTa}{\mathrm{O}}_3$ interfaces through the synergistic ultraviolet (UV) photoexcitation and electrostatic gating. The UV illumination generates high-density photocarriers by promoting valence-to-conduction band transitions, which simultaneously increase the Fermi wave vector $k_{\mathrm{F}}$ and Fermi energy $E_{\mathrm{F}}$. Concurrently, the gate-induced oxygen vacancy migration toward the interface amplifies the Rashba spin-orbit coupling coefficient ${\alpha }_{\mathrm{R}}$. Strikingly, the CPGE photocurrent exhibits a nonmonotonic dependence on both gate voltage and UV intensity, peaking at an optimal carrier density where $k_{\mathrm{F}}$ and ${\alpha }_{\mathrm{R}}$ cooperatively enhance the spin-momentum locking. This dual control strategy achieves a CPGE responsivity of 22.71 µV for $\mathrm{LaAl}{\mathrm{O}}_3/\mathrm{KTa}{\mathrm{O}}_3$ interfaces. Our findings establish the photoelectric coupling as a powerful knob for tailoring nonequilibrium spin phenomena in quantum oxide interfaces, with direct implications for reconfigurable spintronic devices.

We introduce the time glass, a nonperiodic analog of the discrete time crystal that arises in periodically driven dissipative quantum many-body systems. This phase is defined by two key features: (1) spatial long-range order arising from the spontaneous breaking of an internal symmetry and (2) temporally chaotic oscillations of the order parameter, whose lifetime diverges with system size. In other words, a time glass is a state of matter in which all components evolve in a synchronized yet chaotic manner. To characterize the time glass phase, we focus on the spectral gap of the one-cycle (Floquet) Liouvillian, which determines the decay rate of the slowest relaxation mode. Theoretical arguments and numerical studies of periodically driven dissipative Ising models show that, in the time glass phase, the Liouvillian gap remains finite in the thermodynamic limit, in contrast to time crystals where the gap closes exponentially with system size. We further demonstrate that the Liouvillian gap converges to the decay rate of the order-parameter autocorrelation derived from the classical (mean-field) dynamics in the thermodynamic limit. This result establishes a direct correspondence between microscopic spectral features and emergent macroscopic dynamics in driven dissipative quantum systems. At first glance, the existence of a nonzero Liouvillian gap appears incompatible with the presence of indefinitely persistent chaotic oscillations. We resolve this apparent paradox by showing that the quantum Rényi divergence between a localized coherent initial state and the highly delocalized steady state grows unboundedly with system size. This divergence allows long-lived transients to persist even in the presence of a finite Liouvillian gap.

Symmetry plays an important role in the topological band theory. Recently, the concept of subsymmetry-protected topological (sub-SPT) phases [Nat. Phys. 19, 992 (2023)] suggests that chiral edge states can exist in a system with broken symmetry. However, sub-SPT theory only focuses on the zero-energy edge states in the half-filling gap, which limits its application. In this work, we extend the scope of sub-SPT phases in both one-dimensional (1D) and two-dimensional (2D) multigap asymmetric systems through redefined sublattices. In three typical asymmetric models without subsymmetry, we find that all the nonzero edge (corner) states can be illustrated by sub-SPT chiral edge (corner) states after redefining sublattices. Moreover, these nonzero chiral boundary states can exhibit some exotic properties, such as the topological bound states in the continuum. As to the bulk-edge correspondence, a universal topological invariant $\overline{Z}$ is defined, which can precisely predict the appearance of chiral boundary states in both 1D and 2D systems. Finally, we propose an acoustic experiment where the nonzero chiral corner states are numerically observed. Our work exhibits a general approach to study the topological properties of asymmetric systems, opening up possibilities for topological phenomena.

Understanding the interplay between magnetism and superconductivity in nickelate systems is a key objective in condensed matter physics. Gaining microscopic insights into magnetism—particularly as it emerges near superconductivity—requires a synergistic approach that combines complementary experimental techniques with controlled tuning of external parameters. In this paper, we present a systematic investigation of the three-layer Ruddlesden-Popper (RP) nickelate ${\mathrm{La}}_4{\mathrm{Ni}}_3{\mathrm{O}}_{10}$ using muon-spin rotation/relaxation ($\mu \mathrm{SR}$) and resistivity measurements. At ambient pressure, two incommensurate spin-density-wave (SDW) transitions are identified at $T_{\mathrm{SDW}}\simeq 132\mathrm{K}$ and $T^{*}\simeq 80–90\mathrm{K}$. Comparison of the observed internal magnetic fields with dipole-field calculations reveals a magnetic structure consistent with antiferromagnetically coupled SDW order on the outer two Ni-O layers, with smaller moments on the inner Ni-O layer. Above $T^{*}$, the moments lie primarily in the $ab$ plane, but below this temperature they undergo a subtle distortion and develop a $c$-axis component. The internal fields at the muon stopping sites appear abruptly at $T_{\mathrm{SDW}}$, suggesting a first-order-like nature of the SDW transition, which is closely linked to the charge-density wave (CDW) order occurring at the same temperature ($T_{\mathrm{SDW}}=T_{\mathrm{CDW}}$). Under applied pressure, all transition temperatures—including $T_{\mathrm{SDW}}, T^{*}$, and $T_{\mathrm{CDW}}$—are suppressed at a nearly uniform rate of $\simeq -13$ K/GPa. This behavior contrasts with that of the two-layer RP nickelate ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_7$, where pressure enhances the separation between the SDW and CDW transitions. The oxygen-isotope substitution (${}^{16}\mathrm{O} \to {}^{18}\mathrm{O}$) reveals that the CDW transition temperature shifts to higher values in the ${}^{18}\mathrm{O}$-substituted samples. The isotope effect on $T_{\mathrm{SDW}}$ and $T^{*}$ differs significantly. Specifically, when the CDW and SDW orders are intertwined, a notable isotope effect is observed on $T_{\mathrm{SDW}}$, leading to equal transition temperatures and nearly identical isotope shifts for both $T_{\mathrm{CDW}}$ and $T_{\mathrm{SDW}}$. In contrast, at $T^{*}$, where the SDW transition occurs independently of the CDW, no isotope effect is detected.

Understanding the impact of gate errors on quantum circuits is crucial to determining the potential applications of quantum computers, especially in the absence of large-scale error-corrected hardware. We put forward analytical arguments, corroborated by extensive numerical and experimental evidence, that Trotterized quantum circuits simulating the time evolution of systems near thermal equilibrium are substantially more robust to both quantum gate errors and Trotter (discretization) errors than is widely assumed. In Quantinuum’s trapped-ion computers, the weakly entangling gates that appear in Trotterized circuits can be implemented natively, and their error rate is smaller when they generate less entanglement; from benchmarking, we know that the error for a gate $exp[-i(Z\otimes Z\left)\tau \right]$ decreases roughly linearly with $\tau$, up to a small offset at $\tau =0$. We provide extensive evidence that this scaling, together with the robustness of near-thermal dynamics to both gate and discretization errors, facilitates substantial improvements in the achievable accuracy of Trotterized dynamics on near-term quantum computers. We make heavy use of a theoretical tool—a statistical ensemble of random product states that approximates a thermal state, which can be efficiently prepared with low noise on quantum computers. We outline how the random product state ensemble can be used to predict, optimize, and design Hamiltonian simulation experiments on near-thermal quantum systems.

Multitarget gates offer the potential to reduce gate depth in syndrome extraction for quantum error correction. Although neutral-atom quantum computers have demonstrated native multiqubit gates, existing approaches that avoid additional control or multiple atomic species have been limited to single-target gates. We propose single-control multitarget $\mathrm{C}\left(Z^{\otimes N}\right)$ gates on a single-species neutral-atom platform that requires no extra control and has gate durations comparable to standard $\mathrm{C}Z$ gates. Our approach leverages tailored interatomic distances to create an asymmetric blockade between the control and target atoms. Using a graphics processing unit-accelerated pulse synthesis protocol, we design smooth control pulses for $\mathrm{C}ZZ$ and $\mathrm{C}ZZZ$ gates, achieving fidelities of up to $99.55\%$ and $99.24\%$, respectively, even in the presence of simulated atom-placement errors and Rydberg-state decay. Our approach is most effective for $N=2$ $\left(\mathrm{C}ZZ\right)$ and $N=3$ targets $\left(\mathrm{C}ZZZ\right)$; for larger N, increasing spatial crowding of the targets introduces significant challenges for maintaining the required blockade asymmetry. This work presents a practical path to implementing low-overhead multitarget gates in single-species neutral-atom systems, significantly reducing the resource overhead for syndrome extraction. To motivate the impact of these gates, we apply a greedy scheduling algorithm and we demonstrate that our proposed gates can reduce the number of atom reconfiguration costs by up to 50% for color code syndrome extraction of code distances greater than 5.

We describe distinctive stellar features indicating the presence of hyperons in neutron stars as compared to purely nucleonic systems. A strongly negative curvature of the mass-radius relation $R\left(M\right)$ is characteristic of hyperons, which can be determined from measurements of neutron stars with three different masses. Similarly, a reduced second derivative of the tidal deformability as a function of mass $\lambda \left(M\right)$ points to hyperonic degrees of freedom in neutron star matter. The slopes of such curves $R\left(M\right)$ and $\lambda \left(M\right)$ can distinguish a hyperonic equation of state from purely nucleonic models if they appear increased [decreased for $\lambda \left(M\right)$] relative to the maximum mass of neutron stars.

In the pursuit of robust quantum computing, we put forth a platform based on photonic qubits in a circuit-QED environment. Specifically, we propose a versatile two-qubit gate based on two cavities coupled via a transmon, constituting a selective number-dependent phase gate operating on the in-phase eigenmodes of the two cavities, the Eigen-SNAP gate. This gate natively operates in the dispersive coupling regime of the cavities and the transmon, and operates by driving the transmon externally, to imprint desired phases on the number states. As an example for the utility of the Eigen-SNAP gate, we implement a $\sqrt{\text{SWAP}}$ gate on a system of two logical bosonic qubits encoded in the cavities. Further, we use numerical optimization to determine the optimal implementation of the $\sqrt{\text{SWAP}}$. We find that the fidelities of these optimal protocols are only limited by the coherence times of the system's components. These findings pave the way to continuous-variable quantum computing in cavity-transmon systems.