Understanding transport subject to molecular-scale confinement is key to advancing nanofluidics, yet classical hydrodynamic laws often fail at these scales. Here, we study a model system: transport of toluene as a solvent and small fullerenes as model particles confined within alumina slit nanopores using molecular dynamics simulations. We find that toluene organizes into discrete layers whose commensurability with the pore width leads to a striking, nonmonotonic, zigzag dependence of transport coefficients on confinement. This layering drives oscillations not only in solvent diffusivity but also in flow velocity and permeability under pressure-driven conditions, breaking the expected scaling relations between diffusion, viscosity, and flow. Surprisingly, introducing a nanoparticle does not wash out these effects—although the fullerene perturbs local layering, the nanoparticle diffusivity retains a zigzag dependence on pore width. Our results demonstrate how structural commensurability and interfacial effects dominate transport in nanoconfined liquids and lead to important deviations from continuum expectations. These findings establish a microscopic basis for size-dependent transport in nanopores and highlight the need for beyond-hydrodynamic models in confined soft matter systems.

We present a regime of cavity soliton (CS) excitation in a Kerr resonator driven by a train of desynchronized pulses. In this regime, the soliton solution is shown to be the sole available state for the intracavity field, allowing for the automatic excitation of single solitons without the application of any external perturbations or parameter ramping. The self-excitation of cavity soliton frequency combs is validated through numerical continuation of the Lugiato-Lefever equation, direct numerical integration, and experimental observation. We show that this regime of CS self-excitation requires only the cavity detuning and pump desynchronization parameters to be set within the correct range, thus considerably simplifying the usually complex task of deterministic cavity soliton excitation. Additionally, we show that this procedure can also be extended to allow the deterministic generation of different families of multisoliton bound states. We believe that this research offers a promising approach to considerably simplify cavity soliton generation in both macro- and microscale Kerr resonators while also offering greatly increased thermal, power, and nonlinear efficiencies intrinsic to pulsed-driven systems.

Understanding the neural correlates of consciousness remains a central challenge in neuroscience. In this study, we investigate the relationship between consciousness and neural responsiveness by analyzing intracranial electrocorticography recordings from nonhuman primates across three distinct states: wakefulness, anesthesia, and recovery. Using a nonequilibrium recurrent neural network (RNN) model, we fit state-dependent cortical dynamics to extract the neural response function as a dynamics complexity indicator. Our findings demonstrate that the amplitude of the neural response function serves as a robust dynamical indicator of conscious state, consistent with the role of a linear response function in statistical physics. Notably, this aligns with our previous theoretical results showing that the response function in RNNs peaks near the transition between ordered and chaotic regimes—highlighting criticality as a potential principle for sustaining flexible and responsive cortical dynamics. Empirically, we find that during wakefulness, neural responsiveness is strong, widely distributed, and consistent with rich nonequilibrium fluctuations. Under anesthesia, response amplitudes are significantly suppressed, and the network dynamics become more chaotic, indicating a loss of dynamical sensitivity. During recovery, the neural response function is elevated, supporting the gradual re-establishment of flexible and responsive activity that parallels the restoration of conscious processing. Our work suggests that a robust, brain-state-dependent neural response function may be a necessary dynamical condition for consciousness, providing a principled framework for quantifying levels of consciousness in terms of nonequilibrium responsiveness in the brain.

We investigate the generation of strong antibunching photons/photon pairs in a two-atom cavity QED system leveraging interatomic van der Waals (vdW) interaction. We show that the vdW interaction shifts the energy of double excited state, enabling the suppression of two-photon excitation via destructive interference in a diamond configuration. This leads to antibunching photon emission with extremely high purity. Furthermore, by tuning the vdW interaction strength, the conditions for conventional and unconventional photon blockades can be satisfied simultaneously, which significantly enhances the generation of single photon. Conversely, at the antiblockade excitation frequency, quantum Monte Carlo simulations demonstrate the feasibility of generating antibunching photon pairs with a high purity and reasonable leaking rate by selecting appropriate driving field Rabi frequency and vdW interaction strength. These findings on enhanced photon antibunching and photon pair emission may lead to more efficient and brighter quantum light sources, which is a key mechanism for optical quantum devices.

Three-dimensional particle-in-cell simulations are used to demonstrate the generation of highly collimated, dense proton jets from planar hydrogen targets using shaped, petawatt-class, laser pulses formed via simultaneous spatial and temporal focusing (SSTF). Simulations assume a 30 J, 30 fs laser pulse that is engineered with a radial spatial chirp and then focused into a conical space-time structure. An idealized conical structure that might be produced using a pair of circular diffraction gratings is first modeled and then compared to an approximate implementation using a multibeam combination of four 7.5 J pulses that are produced using conventional single-pass grating pairs. Tightly collimated, 5 µm diameter proton jets with peak energies up to 60 MeV are produced in both instances. Unlike target-shaping schemes that require precise manufacturing and alignment, this shaped-pulse approach can enable highrepetition rate, collimated proton beams using existing thin hydrogen sheet technology.

The nonorthogonality of modes in open systems significantly modifies their resonant response, resulting in quantitative and qualitative deviations from Breit-Wigner resonance relations. For isolated resonances with a Lorentzian lineshape, the deviations amount to a quantitative enhancement of the resonance linewidth, given by the Petermann factor, which is determined by the overlap of left and right eigenmodes of the underlying effectively non-Hermitian Hamiltonian. The Petermann factor diverges at exceptional points (EPs), where complex resonance frequencies become degenerate, and right and left eigenmodes are orthogonal to each other. This divergence signifies a qualitative departure from a Lorentzian lineshape, which has moved into the focus of recent attention. In this work, we develop the analog of the Petermann factor for this qualitatively modified response at an EP, and describe how this EP Petermann factor manifests in a variety of physical scenarios. First, we identify this analog in physical terms as an enhancement of the response of a system to external or parametric perturbations. Utilizing two natural orthogonally projected reference systems based on the right and left eigenvectors, we show that each choice carries a precise geometric interpretation that naturally extends the notion of the Petermann factor for isolated resonances to EPs. The two choices can be combined into an overall EP Petermann factor, which again can be expressed in purely geometric terms. Second, we illuminate the geometric mechanisms that determine the size of the EP Petermann factor, by considering the role of modes participating in the degeneracy and those that remain spectrally separated from it. This also leads to a systematic description to evaluate this factor. Third, we design a system that allows us to study the EP Petermann factor in a specific physical setup, consisting of two microrings coupled to a waveguide with embedded semitransparent mirrors. With this example, we demonstrate that our approach gives more accurate results for the spectral response strength than conventional truncation schemes. These results complete the description of systems operating at exceptional points in the same way as the original Petermann factor does for isolated resonances, and pave the way to the design of open systems with unconventional spectral response, be it in emission or in response to static and dynamic perturbations.

The security of quantum key distribution (QKD) is evaluated based on the secrecy of Alice's key and the correctness of the keys held by Alice and Bob. A practical method for ensuring correctness is known as error verification, in which Alice and Bob reveal a portion of their reconciled keys and check whether the revealed information matches. In this paper, we point out that when error verification is performed in a QKD protocol, the definition of secrecy must be revised accordingly. We illustrate the necessity of this revision with a counterexample, showing that neglecting it can lead to an incorrect security claim. In particular, we observe that in the case of the security proof method based on phase error correction, which is one of the mainstream approaches and also known as Koashi's approach, no explicit method has been established to properly incorporate the revised secrecy definition. To resolve this issue, we present a way to translate the phase error correction-based approach into another mainstream approach, called the leftover hash lemma-based approach, also known as Renner's approach, where a solution has already been formulated. As a consequence, security proofs under the phase error correction-based approach automatically remain valid without any change in the secret key length, even if they implicitly consider error verification without revising the secrecy definition.

We present third-order and first-order dielectric measurements on a series of $N$-propylene glycol ($N$-PG) oligomers, focusing on the role of molecular length $N$ in the glass transition. To avoid polymeric effects, we restricted the study to short chains ($N=1–20$). Linear dielectric susceptibility $\mathrm{\Delta }{\chi }_1$ scales as $\frac{1}{N}$, suggesting that only the terminal hydroxyl (–OH) groups contribute significantly to the dipolar response, while the flexible backbone units remain largely inactive. Third-order susceptibilities ${\chi }_3^{\left(3\right)}$ exhibit a growing hump upon cooling for all $N$-PG, consistent with the Bouchaud-Biroli prediction. This allows us to extract the relative evolution of the number of dynamically correlated molecules $N_{\mathrm{corr}}$, which is as expected increasing upon cooling. But surprisingly, this evolution is identical across all oligomers, regardless of chain length, even though the size of the largest molecules likely exceeds that of the dynamic heterogeneities. This robustness of the relative evolution of $N_{\mathrm{corr}}\left({\tau }_{\alpha }\right)$ allows to deduce that it is insensitive to the backbone linking the monomers, the fragility, the OH-bond density, or the strength of the dipole-dipole interactions among oligomers, standard criteria to describe the phenomenon. These findings challenge kinetically constrained models, which fail to account for the observed behavior, while supporting the predictions of the random first-order transition theory.

An interacting quantum system and thermal bath can reach thermal equilibrium, resulting in the system and bath acquiring the same temperature. But how does a delocalized quantum system thermalize with a bath whose local temperature varies as, for example, in the Tolman effect? Here, we formulate two scenarios in which the notion of a “superposition of temperatures” may arise: first, a probe interaction with two different baths dependent on the state of another quantum system (a control); and second, a probe interaction with a single bath whose purified state is a superposition of states that each correspond to different temperatures. We show that the two scenarios are fundamentally different and can be operationally distinguished. Moreover, we show that the final probe state is sensitive to the specific realization of the thermalizing channels, and that our results hold for partial and prethermalization cases. Our models may be applied to scenarios involving joint quantum and relativistic phenomena, and explain some recent results found in quantum interference of relativistic probes thermalizing with Unruh or Hawking radiation.

We report spectroscopic and time-resolved experimental observations to characterize the $\left[\mathrm{Xe}\right]4f^{13}\left({}^{2}F_{5/2}^o\right)5d6s\left({}^{1}D\right){}^1{[5/2]}_{5/2}^o$ state in ${}^{172}\mathrm{Yb}^{+}$ ions. We access this state from the metastable $4f^{14}5d\left({}^{2}D_{3/2,5/2}\right)$ manifold and observe an unexpectedly long lifetime of $\tau =37.9\left(9\right)\mu \mathrm{s}$ that allows visible Rabi oscillations and resolved-sideband spectroscopy. Using a combination of coherent population dynamics, high-fidelity detection and heralded state preparation, and optical pumping methods, we measure the branching ratios to the ${}^{2}D_{3/2}, {}^{2}D_{5/2}$, and ${}^{2}S_{1/2}$ states to be $0.359\left(2\right)$, 0.639(2), and $0.0023\left(16\right)$, respectively. The branching ratio to the $4f^{13}6s^2\left({{}^{2}F}_{7/2}\right)$ is compatible with zero within our experimental resolution. We also report measurements of Landé $g$-factor of the ${}^1{[5/2]}_{5/2}^o$ state. Further, the branching ratio of the ${}^{2}D_{5/2}$ to ${}^{2}S_{1/2}$ decay in ${}^{172}\mathrm{Yb}^{+}$ was measured to be 0.188(3), improving its relative uncertainty by an order of magnitude. Our measurements provide experimental benchmarks for better understanding the atomic structure of ${\mathrm{Yb}}^{+}$ ions, which still lacks accurate numerical descriptions, and the use of high-lying excited states for partial detection and qubit manipulation in the omg architecture.

Recent work has introduced the concept of finite-time scaling to characterize bifurcation diagrams at finite times in deterministic discrete dynamical systems, drawing an analogy with finite-size scaling used to study critical behavior in finite systems. In this work, we extend the finite-time scaling approach in several key directions. First, we present numerical results for one-dimensional maps exhibiting period-doubling bifurcations and discontinuous transitions, analyzing selected paradigmatic examples. We then define two observables, the finite-time susceptibility and the finite-time Lyapunov exponent, that also display consistent scaling near bifurcation points. The method is further generalized to special cases of two-dimensional (2D) maps including the 2D Chialvo map, capturing its bifurcation between a fixed point and a periodic orbit, while accounting for discontinuities and asymmetric periodic orbits. These results underscore fundamental connections between temporal and spatial observables in complex systems, suggesting avenues for studying complex dynamical behavior.

The dynamics of phase-separated interfaces shape the behavior of both passive and active condensates. While surface tension in equilibrium systems minimizes interface length, nonequilibrium fluxes can destabilize flat or constantly curved interfaces, giving rise to complex interface morphologies. Starting from a minimal model that couples a conserved, phase-separating species to a self-generated chemical field, we identify the conditions under which interfacial instabilities may emerge. Specifically, we show that nonreciprocal chemotactic interactions induce two distinct types of instabilities: a stationary (nonoscillatory) instability that promotes interface deformations and an oscillatory instability that can give rise to persistent capillary waves propagating along the boundaries of phase-separated domains. To characterize these phenomena, we develop a perturbative framework that predicts the onset, wavelength, and velocity of capillary waves, and quantitatively validate these predictions through numerical simulations. Beyond the linear regime, our simulations reveal that capillary waves undergo a secondary instability, leading to either stationary or dynamically evolving superpositions of different wave modes. Finally, we investigate whether capillary waves can facilitate directed mass transport, either along phase boundaries (conveyor belts) or through self-sustained liquid gears crawling along a solid wall. Taken together, our results establish a general framework for interfacial dynamics in active phase-separating systems and suggest strategies for controlling mass transport in soft matter and biological condensates.

We present experimental results in which a quasimonolayer of grains, shaped as equilateral triangular prisms, is vertically vibrated within circular and square confining cavities. The system exhibits a fluid phase characterized by sixfold orientational order. However, the specific geometries of the cavities frustrate this order, leading to the excitation of topological defects that adhere to topological principles. We analyze the distribution of topological charges of these defects and their evolution as a function of the container geometry. In particular, we find that in the circular cavity, both the number and charge of defects remain constant in the steady-state regime, with only defects of charge $+1$ being excited. In contrast, within the square cavity—with the same topology as the circular cavity—some defects become pinned to the corners of the cavity, developing charges of $+1$ or $+2$. Additionally, free defects with charges of $\pm 1$ can be excited. Notably, dynamic events occur, such as the fusion of two defects or the creation of two defects from a single one. These events are governed by the conservation of total charge within the cavity and give rise to various system configurations, with rapid transitions between them. The observed dynamic fluctuations in topological charge are remarkable, influenced by both particle shape and cavity geometry. This system of vertically vibrated (dissipative) granular monolayers presents a unique and simple platform for studying topological phenomena, with potential implications for topological effects in equilibrium-oriented fluids.