Photomagnetic effects (PMEs), intrinsic to transition metals, arise from the interaction between light-induced angular momentum and electronic spin. These effects are suppressed in noble metals with high symmetry and electron density. Introducing chiral structures can induce photomagnetic-chiral anisotropy (PMChA) of metals by linking chirality and spin dynamics. However, a theoretical explanation remains elusive. Here, we investigated the mechanism of PMChA in tetrahelix-stacked chiral nanostructured Au chains (CNACs) using first-principles calculations. Nonequilibrium Green’s function calculations reveal that chiral potentials enhance spin channel asymmetry by amplifying spin-orbit coupling (SOC)-induced spin splitting. Real-time time-dependent density functional theory simulations further identify SOC as the bridge connecting chiral spintronics to PMEs, where chirality-driven spin flips from asymmetric geometries generate opposing photomagnetic fields in materials of different handedness. These findings are consistent with experimental observations in chiral nanostructured gold films and provide theoretical guidance for designing metallic spintronic devices.

Stochastic resetting breaks detailed balance and drives the formation of nonequilibrium steady states. Here, we consider a chain of diffusive processes $x_i(t)$ that interact unilaterally: at random time intervals, the process $x_n$ stochastically resets to the instantaneous value of $x_{n-1}$. We derive analytically the steady-state statistics of these nested stochastic resetting processes including the stationary distribution for each process as well as its moments. We are also able to calculate exactly the steady-state two-point correlations $⟨x_n{x}_{n+j}⟩$ between processes by mapping the problem to one of the ordering statistics of random counting processes. Understanding statistics and correlations in many-particle nonequilibrium systems remains a formidable challenge and our results provide an example of such tractable correlations. We expect this framework will both help build a model-independent framework for random processes with unilateral interactions and find immediate applications, e.g., in the modeling of lossy information propagation.

Complex dynamical systems, from macromolecules to ecosystems, are often modeled by stochastic differential equations. To learn such models from data, a common approach involves sparse selection among a large function library. However, we show that overfitting arises not just from individual model complexity, but also from the combinatorial growth of possible models. To address this, we introduce parsimonious stochastic inference (PASTIS), a principled method combining likelihood-estimation statistics with extreme value theory to suppress superfluous parameters. PASTIS outperforms existing methods and reliably identifies minimal models, even with low sampling rates or measurement error. It extends to stochastic partial differential equations, and applies to ecological networks and reaction-diffusion dynamics.

Dynamical phase transitions (DPTs) characterize critical changes in system behavior occurring at finite times, providing a lens to study nonequilibrium phenomena beyond conventional equilibrium physics. While extensively studied in quantum systems, DPTs have remained largely unexplored in classical settings. Recent experiments on complex systems, from social networks to financial markets, have revealed abrupt dynamical changes analogous to quantum DPTs, motivating the search for a theoretical understanding. Here, we present a minimal model for nonequilibrium networks, demonstrating that nonlinear interactions among network edges naturally give rise to DPTs. Specifically, we show that network degree diverges at a finite critical time, following a universal hyperbolic scaling, consistent with empirical observations. Our analytical results predict that key network properties, including degree distributions and clustering coefficients, exhibit critical scaling as criticality approaches. These findings establish a theoretical foundation for understanding emergent nonequilibrium criticality across diverse complex systems.

Run-and-tumble (RT) motion is commonly observed in flagellated microswimmers, arising from synchronous and asynchronous flagellar beating. One such example is a biflagellated alga, called Chlamydomonas reinhardtii. Its flagellar synchronization is not only affected by hydrodynamic interactions but also through contractile stress fibers that mechanically couple the flagella, enabling adaptable swimming behavior. To explore this, we design a macroscopic mechanical system that comprises dry, self-propelled robots linked by a rigid rod to model this organism. By varying the attachment points of the two ends of the rod on each robot, the model incorporates the effect of fiber contractility observed in the real organism. To mimic a low Reynolds number environment, we program each robot to undergo overdamped active Brownian (AB) motion. We find that such a system exhibits RT-like behavior, characterized by sharp, direction-reversing tumbles and exponentially distributed run times, consistent with the real organism. Moreover, we quantify tumbling frequency and demonstrate its tunability across experimental parameters. Additionally, we provide a theoretical model that reproduces our results, elucidating physical mechanisms governing RT dynamics. Thus, our robotic system not only replicates RT motion but also captures several subtle characteristics, offering valuable insights into the underlying physics of microswimmer motility.

Local-operator entanglement (LOE) dictates the complexity of simulating Heisenberg evolution using tensor network methods, and it bears witness to many-body chaos for local dynamics. We show that LOE is also sensitive to how non-Clifford a unitary is—its magic resources. In particular, we prove that LOE is always upper-bound by three distinct magic monotones: $T$-count, unitary nullity, and operator-stabilizer Rényi entropy. Moreover, in the average case for large, random circuits, LOE and magic monotones approximately coincide. Our results imply that an operator evolution that is expensive to simulate using tensor network methods must also be inefficient using both stabilizer and Pauli truncation methods. In terms of a previous conjecture on the characteristic scaling of LOE, our results imply that nonintegrable spin chains cannot be simulated classically. Entanglement in operator space therefore measures a unified picture of nonclassical resources, in stark contrast to the Schrödinger picture.

Agents often execute complex strategies, adapting their response to each input stimulus depending on past observations and actions. Here, we derive the minimal energetic cost for classical agents to execute a given strategy, highlighting that they must dissipate a certain amount of heat with each decision beyond Landauer’s limit. We then prove that quantum agents can reduce this dissipation below classical limits. We establish the necessary and sufficient conditions for a strategy to guarantee quantum agents have energetic advantage, and illustrate settings where this advantage grows without bound. Our results establish a fundamental energetic advantage for agents utilizing quantum processing to enact complex adaptive behavior.

In quantum mechanics, the probability distribution function and full counting statistics play a fundamental role in characterizing the fluctuations of quantum observables, as they encode the complete information about these fluctuations. In this Letter, we measure these two quantities in a trapped-ion quantum simulator for the transverse and longitudinal magnetization within a subsystem. We utilize the toolbox of classical shadows to postprocess the measurements performed in random bases. The measurement scheme efficiently allows access to the full counting statistics and probability distribution function of all possible operators on desired choices of subsystems of an extended quantum system.

We present a novel approach to cryptographically secure verification and benchmarking of quantum computing, demonstrating our approach on an ion-trap quantum computer. Unlike previous cryptographically secure verification protocols, which typically require quantum communication between client and server, our approach is implemented entirely on chip. This eliminates the need for a quantum capable client, and significantly enhances practicality. We perform tomography to justify the additionally required assumption that the noise is independent of the secret used to prepare the server’s single-qubit states. We quantify the soundness error that may be caused by residual secret dependencies. We demonstrate our protocol on the 20-qubit Quantinuum H1-1 ion-trap quantum processing unit, using qubit measurements and resets to construct measurement patterns with up to 52 vertices. To our knowledge, these are the largest verified measurement-based quantum computations performed to date.

We discuss Bell nonlocality in quantum networks with unreliable sources. Our main result is a condition on the observed data that ensures that inconclusive events can be safely discarded, without introducing any loophole. More formally, we characterize the fair-sampling property for measurements in a network. When all measurements are fair-sampling, we show that the postselection of conclusive outcomes does not compromise the assumption of source independence, hence avoiding the detection loophole. Furthermore, we show that in some cases, the fair-sampling property can in fact be certified directly from observed data. To show this, we prove that saturation of the Finner inequality provides a self-test of the underlying quantum model. We illustrate the relevance of our results by demonstrating an improvement in device-independent randomness generation for a photonic Bell test with a probabilistic source and for the triangle network.

Bell nonlocality without input settings, .g., in the triangle network, has been perceived to be particularly fragile, with low robustness to noise in physical implementations. Here, we show to the contrary that nonlocality based on N00N states already for $N=2$ has an exceptionally high robustness to photon loss. For the dominant noise factor, single photon loss in the transmission channels, we can certify noise robustness up to 10% loss, while for a realistic noise model we use neural network-based heuristics to observe $\sim 50\%$ robustness. Moreover we show that the robustness holds even for imperfect sources based on spontaneous parametric down-conversion sources, where the heralding information of the sources can be used to avoid any global postprocessing of the outcomes, such as discarding rounds when photons fail to arrive, and thus demonstrate how the detection loophole in the triangle network can be closed.

Achieving precise control over quantum systems presents a significant challenge, especially in many-body setups, where residual couplings and unintended transitions undermine the accuracy of quantum operations. In superconducting qubits, parasitic interactions—both between distant qubits and with spurious two-level systems—can severely limit the performance of quantum gates. In this Letter, we introduce a pulse-shaping technique that uses spectrally balanced microwave pulses to suppress undesired transitions. Experimental results demonstrate an order-of-magnitude reduction in spurious excitations between weakly detuned qubits as well as a substantial decrease in single-qubit gate errors caused by a strongly coupled two-level defect over a broad frequency range. Our method provides a simple yet powerful solution for mitigating adverse effects from parasitic couplings, enhancing quantum gate fidelity. The pulse-shaping technique can be readily adapted to various physical systems.

We show that the simplest generalization of the chaotic inflation model $\frac{1}{2}{m}^2{\varphi }^2$ with nonminimal coupling to gravity $(1+\varphi )R$ provides a good match to the results of the latest data release of the Atacama Cosmology Telescope and South Pole Telescope, with $r\approx {10}^{-2}$.

We examine the most general nucleon decay interactions that involve three light quarks without being acted upon by a derivative. We identify four generic operator structures that correspond to the irreducible representations in the chiral group ${\mathrm{SU}(3)}_{\mathtt{L}}\otimes {\mathrm{SU}(3)}_{\mathtt{R}}$ of QCD, $\{{\mathbf{8}}_{\mathtt{L}}\otimes {\mathbf{1}}_{\mathtt{R}},{\overline{\mathbf{3}}}_{\mathtt{L}}\otimes {\mathbf{3}}_{\mathtt{R}},{\mathbf{6}}_{\mathtt{L}}\otimes {\mathbf{3}}_{\mathtt{R}},{\mathbf{10}}_{\mathtt{L}}\otimes {\mathbf{1}}_{\mathtt{R}}\}$, plus their chirality partners under the interchange of chiralities $\mathtt{L}\leftrightarrow \mathtt{R}$. While half of them have been extensively discussed in the literature, the other half, ${\mathbf{6}}_{\mathtt{L}(\mathtt{R})}\otimes {\mathbf{3}}_{\mathtt{R}(\mathtt{L})}$ and ${\overline{\mathbf{10}}}_{\mathtt{L}(\mathtt{R})}\otimes {\mathbf{1}}_{\mathtt{R}(\mathtt{L})}$, are identified for the first time. We perform chiral matching for these interactions at the leading chiral order and find that each has a unique chiral realization in terms of the octet baryons and pseudoscalars. Notably, the chiral interaction in the ${\mathbf{6}}_{\mathtt{L}(\mathtt{R})}\otimes {\mathbf{3}}_{\mathtt{R}(\mathtt{L})}$ representation appears at the same chiral order as those of the known ones, while the one in the ${\mathbf{10}}_{\mathtt{L}(\mathtt{R})}\otimes {\mathbf{1}}_{\mathtt{R}(\mathtt{L})}$ representation appears at a higher chiral order. These new structures are prevalent in effective field theories and ultraviolet models, and they offer novel experimental avenues to search for baryon number violating nucleon decays.

The ${\mathrm{\Xi }}_c^{+}{\pi }^{-}{\pi }^{+}$ spectrum is investigated using proton-proton collisions at a center-of-mass energy of 13 TeV, corresponding to an integrated luminosity of $5.4{\mathrm{fb}}^{-1}$, collected by the LHCb experiment during 2016–2018. Four states are observed with high significance, and their masses and widths are measured to be $m[{\mathrm{\Xi }}_c(2815{)}^{+}]=2816.65\pm 0.03\pm 0.03\pm 0.23\mathrm{MeV}$, $\mathrm{\Gamma }[{\mathrm{\Xi }}_c(2815{)}^{+}]=2.07\pm 0.08\pm 0.12\mathrm{MeV}$, $m[{\mathrm{\Xi }}_c(2923{)}^{+}]=2922.8\pm 0.3\pm 0.5\pm 0.2\mathrm{MeV}$, $\mathrm{\Gamma }[{\mathrm{\Xi }}_c(2923{)}^{+}]=5.3\pm 0.9\pm 1.4\mathrm{MeV}$, $m[{\mathrm{\Xi }}_c(2970{)}^{+}]=2968.6\pm 0.5\pm 0.5\pm 0.2\mathrm{MeV}$, $\mathrm{\Gamma }[{\mathrm{\Xi }}_c(2970{)}^{+}]=31.7\pm 1.7\pm 1.9\mathrm{MeV}$, $m[{\mathrm{\Xi }}_c(3080{)}^{+}]=3076.8\pm 0.7\pm 1.3\pm 0.2\mathrm{MeV}$, $\mathrm{\Gamma }[{\mathrm{\Xi }}_c(3080{)}^{+}]=6.8\pm 2.3\pm 0.9\mathrm{MeV}$, where the uncertainties are statistical, systematic, and due to the limited precision on the ${\mathrm{\Xi }}_c^{+}$ mass, respectively. The ${\mathrm{\Xi }}_c(2923{)}^{+}$ baryon is observed for the first time, and is consistent with being the isospin partner of the previously observed ${\mathrm{\Xi }}_c(2923{)}^0$ state. Most of the measured parameters are more precise than existing world averages.

The presence of a strong shallow heat source of unknown origin in accreting neutron star crusts has been inferred by analyzing x-ray observations of their cooling in quiescence. We model the cooling of KS 1731–260 using realistic crust compositions and nuclear heating and cooling sources from detailed nuclear reaction network calculations. We find that the required strength of the shallow heat source in KS 1731–260 is reduced by more than a factor of 3 compared to previous analysis, a $5\sigma$ difference that alleviates the need for exotic solutions. Our analysis also suggests the existence of an impure nuclear pasta layer in the inner crust of KS 1731–260, though future observations will provide more stringent constraints. In addition, we obtain constraints on the dominant surface burning modes of KS 1731–260 over its history.

We demonstrate that calculating the spontaneous emission decay rate from metastable resonance states (states with finite lifetimes embedded in the continuum) requires considering transitions to all continuum states, not just to lower states. This holds even when the lifetimes of the metastable states are very long and might be effectively considered as bound states in the continuum. However, employing complex-scaling transformations, this computationally prohibitive task becomes feasible by utilizing methods originally designed for excited bound states for calculation of complex poles of the scattering matrix. As an illustrative example, these methods are applied to calculate the spontaneous emission decay rates of metastable resonance states in a double-barrier potential. The rapid numerical convergence of this approach highlights a new avenue for studying spontaneous emission from metastable states in real-life systems, particularly in many-electron systems, where calculation of the spontaneous emission decay rate from metastable resonances (e.g., autoionization states) is computationally difficult, if not impossible, using the standard (Hermitian) formalism of quantum mechanics.

We present Meissner-like photon currents in a quantum Rabi zigzag chain under staggered synthetic magnetic fields. The ground state of the Meissner superradiant phase hosts persistent chiral edge currents in a sequence of cancellation of antiparallel vortex pairs, akin to surface currents of the Meissner effect in superconductors. The Meissner phase displays distinct vortex structures and anomalous scaling exponents, arising from geometric frustration effects. Modifying the staggered flux triggers transitions to even- or odd-vortex superradiant phases, where the chiral edge currents flow exclusively in even or odd cavities with localized vortices, respectively. Enhanced interspecies interactions induce the vanishing of currents in a ferromagnetic superradiant phase. Our results enable observation of stabilized photon vortices and edge currents with analogy to quantum Hall-like robustness in light-matter coupling systems.