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.

Domain walls in disordered ferromagnets—interfaces separating oppositely magnetized regions—are commonly modeled as elastic interfaces in random media. However, real domain walls possess internal degrees of freedom related to the local magnetization direction at the wall's midpoint, which are not captured by simple elastic interface models. Here, we investigate how these internal degrees of freedom influence Barkhausen noise arising from the jerky field-driven motion of linelike domain walls in disordered thin ferromagnetic films with strong perpendicular magnetic anisotropy. Using a recently developed reduced model that incorporates internal wall dynamics, we simulate systems two orders of magnitude larger than those accessible via full micromagnetic simulations. We focus on Bloch line dynamics and identify a disorder-driven mechanism where Bloch lines accumulate near the edges of moving wall segments during avalanches, thereby impeding further propagation. This mechanism leads to distinctive statistical features in Barkhausen avalanches, including pronounced bumps in the cutoffs of the avalanche distributions, skewness of the average avalanche shape evolving with the avalanche duration, and reduced domain wall roughness at large scales.

Simulating time evolution is one of the most natural applications of quantum computers and is thus one of the most promising prospects for achieving practical quantum advantage. Here, we develop quantum algorithms to extract thermodynamic properties by estimating the density of states (DOS), which is a central object in quantum statistical mechanics. We introduce several key innovations that significantly improve the practicality and extend the generality of previous techniques. First, our approach allows one to estimate the DOS only for a specific subspace of the full Hilbert space. This is crucial for fermionic systems, since both canonical and grand canonical ensemble thermal equilibrium properties depend on subspaces of fixed number. Second, in our approach, by time evolving very simple, random initial states, such as randomly chosen computational basis states, we can exactly recover the DOS on average. Third, due to circuit-depth limitations, we only reconstruct the DOS up to a convolution with a Gaussian window—thus all imperfections that shift the energy levels by less than the width of the convolution window will not significantly affect the estimated DOS. For these reasons, we find the approach is a promising candidate for early quantum advantage as even short-time, noisy dynamics can yield a semiquantitative reconstruction of the DOS (convolution with a broad Gaussian window), while early fault-tolerant devices will likely enable higher-resolution DOS reconstruction through longer time evolutions. We demonstrate the practicality of our approach in representative Fermi-Hubbard and spin models and indeed find that our approach is highly robust against algorithmic errors in the time evolution and against gate noise. We further demonstrate that our approach is compatible with noisy intermediate-scale quantum (NISQ) computing NISQ-friendly variational techniques, introducing and leveraging a technique for variational time evolution.

We use the transfer tensor method to analyze localization and transport in simple disordered systems, specifically the Anderson and Aubry-André-Harper models. Emphasis is placed on the memory effects that emerge when ensemble-averaging over disorder, even when individual trajectories are strictly Markovian. We find that transfer tensor memory effects arise to remove fictitious terms that would correspond to redrawing static disorder at each time step, which would create a temporally uncorrelated dynamic disorder. Our results show that while eternal memory is a necessary condition for localization, it is not sufficient. We determine that signatures of localization and transport can be found within the transfer tensors themselves by defining a metric called “outgoing pseudoflux.” This work establishes connections between theoretical research on dynamical maps and Markovianity and localization phenomena in physically realizable model systems.