The surface roughness of a thin film at a liquid interface exhibits contributions of thermally excited fluctuations. This thermal roughness depends on temperature ($T$), surface tension ($\gamma$), and elastic material properties, specifically the bending modulus ($\kappa$) of the film. A nonzero $\kappa$ suppresses the thermal roughness at small length scales compared to an interface with zero $\kappa$, as expressed by the power spectral density of the thermal roughness. The description of the x-ray scattering of the standard capillary wave model (CWM), which is valid for zero $\kappa$, is extended to include the effect of $\kappa$. The extended CWM (eCWM) provides a single analytical form for both the specular x-ray reflectivity (XRR) and the diffuse scattering around the specular reflection, and recovers the expression of the CWM at its zero $\kappa$ limit. This theoretical approach enables the use of single-shot grazing incidence x-ray off-specular scattering (GIXOS) measurements for characterizing the structure of thin films on a liquid surface. The eCWM analysis approach decouples the thermal roughness factor from the surface scattering signal, providing direct access to the intrinsic surface-normal structure of the film and its bending modulus. Moreover, the eCWM facilitates the calculation of reflectivity at any desired resolution (pseudo-XRR approach). The transformation into pseudo-XRR provides the benefit of using widely available XRR software to perform GIXOS analysis. The extended range of the vertical scattering vector ($Q_z$) available with the GIXOS pseudo-XRR approach allows for a higher spatial resolution than with conventional XRR. Experimental results are presented for various lipid systems, showing strong agreement between conventional specular XRR and pseudo-XRR methods. This agreement validates the proposed approach and highlights its utility for analyzing soft, thin films.

We present a theoretical study of delta-kick collimation (DKC) applied to heteronuclear Feshbach molecules, focusing on both condensed and thermal ensembles across various interaction and temperature regimes. We demonstrate that DKC enables significant reductions in molecular cloud expansion energies and beam divergence, achieving expansion energies in the picokelvin range, comparable to state-of-the-art results obtained experimentally with atoms. Furthermore, we show that vibrational and translational motions remain strongly decoupled throughout the process, and that the vibrational energy remains well below the molecular binding energy, thereby ensuring molecular stability during the delta kick. This work paves the way for advanced experimental sequences involving degenerate ground-state molecules, light-pulse molecular interferometry, and applications of dual-species precision measurements, such as testing the universality of free fall.

Quantum-enhanced sensors, which surpass the standard quantum limit (SQL) and approach the fundamental precision limits dictated by quantum mechanics, are finding applications across a wide range of scientific fields. This quantum advantage becomes particularly significant when a large number of particles are included in the sensing circuit. Achieving such enhancement requires introducing and preserving entanglement among many particles, posing significant experimental challenges. In this work, we integrate concepts from Floquet theory and quantum information to design an entangler capable of generating the desired entanglement between two paths of a quantum interferometer. We demonstrate that our path-entangled states enable sensing beyond the SQL, reaching the fundamental Heisenberg limit (HL) of quantum mechanics. Moreover, we show that a decoding parity measurement maintains the HL when specific conditions from Floquet theory are satisfied—particularly those related to the periodic driving parameters that preserve entanglement during evolution. We address the effects of a priori phase uncertainty, imperfect transmission, and other types of noises, showing that our method remains robust under realistic conditions. Finally, we propose a superconducting-circuit implementation of our sensor in the microwave regime, highlighting its potential for practical applications in high-precision measurements.

We demonstrate longtime coherent subharmonic motion of a many-boson system subjected to an external time-periodic driving force. The underlying mechanism is exemplified numerically through analysis of a periodically driven Bose-Hubbard dimer, and clarified conceptually by semiclassical requantization of invariant tubes pertaining to the system’s mean-field description. In this way, one arrives at pre-Floquet states that relate to the actual many-body Floquet states in a manner similar to the relation of site-localized Wannier states to lattice-extended Bloch states in solid-state physics. It is argued that even high-order subharmonic response can be systematically engineered, and be observed experimentally, with weakly interacting Floquet condensates comprising a sufficiently large number of particles.

We study the nature of thermalization dynamics and the associated preparation (simulation) time under the repeated interaction protocol uncovering an anomalous, Mpemba-like trend. As a case study, we focus on a three-level system and analyze its dynamics in two complementary regimes, where the system-ancilla interaction strength is either large or small. Focusing on the estimation of the simulation time, we derive closed-form expressions for the minimum number of collisions, or minimal simulation time, required to achieve a thermal state, which is within $\epsilon$ distance to the target thermal state. At zero temperature, we analytically identify a set of points (interaction strength $\times$ their duration) that minimize the simulation time. At nonzero temperature, we observe a Mpemba-like effect: Starting from a maximally mixed state, thermalization to an intermediate-temperature state takes longer than to a lower-temperature one. We provide an accurate analytical approximation for this phenomenon and demonstrate its occurrence in larger systems and under randomized interaction strengths. The prevalence of the Mpemba effect in thermal state preparation presents a significant challenge for preparing states in large systems, an open problem calling for new strategies.

Raman optical activity (ROA) offers a powerful tool for distinguishing chiral molecules. However, the inherent properties of light that unveil the “handedness” of molecules remain unclear in the realm of ROA. Here, we find two optical measures—the optical chirality tensor and the optical quadrupole tensor—that contribute to ROA excitations. Subsequently, we propose a theoretical framework to elucidate the relationship between the optical chirality quantities and their molecular counterparts in Raman scattering. This framework allows for more selective and tunable ROA excitations. As a demonstration, we identify linearly polarized standing waves as a good configuration for superchiral ROA excitations, where the optical chirality is locally enhanced. Our work provides insights into optical chirality and paves the way to precisely manipulate chiroptical responses.

Matrix-product states (MPS) have proven to be a versatile ansatz for modeling quantum many-body physics. For many applications, and particularly in one-dimension, they capture relevant quantum correlations in many-body wave functions while remaining tractable (polynomial scaling) to store and manipulate on a classical computer. This has motivated researchers to also apply the MPS ansatz to machine learning (ML) problems where capturing complex correlations in datasets is also a key requirement. Here, for the first time, we develop an MPS-based algorithm, MPSTime, for learning a joint probability distribution underlying a time-series dataset, and show how it can be used to tackle important time-series ML problems, including classification and imputation. MPSTime can efficiently learn complicated time-series probability distributions directly from data, requires only moderate maximum MPS bond dimension ${\chi }_{\max }$ (with values for our applications ranging between ${\chi }_{\max }=20-160$), and can be trained for both classification and imputation tasks under a single logarithmic loss function. Using synthetic and publicly available real-world datasets—spanning applications in medicine, energy, and astronomy—we demonstrate performance competitive with state-of-the-art ML approaches, but with the key advantage of encoding the full joint probability distribution learned from the data, which is useful for analyzing and interpreting its underlying structure. This manuscript is supplemented with the release of a publicly available code package MPSTime that implements our approach, and can be used to reproduce all presented results. The effectiveness of the MPS-based ansatz for capturing complex correlation structures in time-series data makes it a powerful foundation for tackling challenging time-series analysis problems across science, industry, and medicine.

Quantum error correction protects quantum information against decoherence, provided the noise strength remains below a critical threshold. This threshold marks the critical point for the decoding phase transition. Here, we connect this transition in the toric code to a topological phase transition in disordered Majorana fermions at high temperatures. A quantum memory in the error-correctable phase is captured by the presence of a Majorana zero mode, trapped in vortex defects associated with twisted boundary conditions. These results are established by expressing the coherent information, which measures the amount of recoverable quantum information in a given noisy code, in terms of a mixed-state topological order parameter of fermions. Our work hints at a broader connection of the robustness of quantum information in stabilizer codes and mixed-state topological phase transitions in symmetry-protected fermion matter.

Liquid mixtures of many interacting components often exhibit numerous coexisting types of droplets. An exciting example is the cytosol of biological cells, where diverse droplets, known as condensates, enable cellular functions. However, how much their formation is constrained by thermodynamics is currently unclear because we lack predictions for generic multicomponent fluids. Linear stability analysis suggests that homogeneous mixtures become more robust to fluctuations as the number of components increases, so droplets might not form easily in multicomponent mixtures. In contrast, we show through numerical simulations and analytical scaling laws that the number of coexisting phases typically increases with the number of components in equilibrium. The combination of both results suggests that generic multicomponent mixtures can maintain many metastable states with various droplets, generalizing the nucleation-and-growth regime of binary mixtures. Our scaling laws also indicate why cells exhibit much fewer condensates than components and how they could exploit multistability to form various condensates independently.

Recent advances in nonreciprocal topological networks have discovered a type of anomalous topological edge states with superior robustness against larger disorders than the quasienergy band gap. However, to date, all previously demonstrated nonreciprocal topological networks have required external drives such as magnetic fields or time modulation to break the time-reversal symmetry (TRS). Here, by extending this concept to topological active matter systems with spontaneous TRS breaking, we demonstrate robust acoustic anomalous and Chern edge states in a self-propelled nonreciprocal active-liquid network without any external drives. More interestingly, we show that the anomalous topological edge states exhibit superior robustness against Hermitian disorders even than the Chern ones. Furthermore, we discover that such superior robustness no longer holds in the presence of non-Hermitian perturbations, and both the anomalous and Chern edge states transition to the corner skin modes by the non-Hermitian skin effect. Our work extends the nonreciprocal topological networks to active matter and non-Hermitian systems, offering possibilities for sound manipulation in a highly unusual way.

Squeezed vacuum, a fundamental resource for continuous-variable quantum information processing, has been used to demonstrate quantum advantages in sensing, communication, and computation. While most experiments use homodyne detection to characterize squeezing and are therefore limited to electronic bandwidths, recent experiments have shown optical parametric amplification (OPA) to be a viable measurement strategy. Here, we realize OPA-based quantum state tomography in integrated photonics and demonstrate the generation and all-optical Wigner tomography of squeezed vacuum in a nanophotonic circuit. We employ dispersion engineering to enable the distortion-free propagation of femtosecond pulses and achieve ultrabroad operation bandwidths, effectively lifting the speed restrictions imposed by traditional electronics on quantum measurements with a theoretical maximum clock speed of 6.5 THz. We implement our circuit on thin-film lithium niobate, a platform compatible with a wide variety of active and passive photonic components. Our results chart a course for realizing all-optical ultrafast quantum information processing in an integrated room-temperature platform.

The glass transition of supercooled liquids poses a significant challenge in statistical physics. Although the glass transition has been extensively investigated in various active systems, the influence of nonreciprocal interactions between particles on this transition remains an open question. In this study, we investigate the diffusion and glass transition within a two-dimensional Kob-Andersen mixture featuring nonreciprocal particle interactions. Our findings reveal that nonreciprocity among particles profoundly impacts the system's dynamics. Specifically, in the gaseous or high-temperature liquid phase, the diffusion coefficient exhibits a consistent increase with rising nonreciprocity. However, in the viscous liquid or glassy state, the emergence of large-scale directed motion leads to a weakly nonmonotonic relationship between the diffusion coefficient and nonreciprocity. As nonreciprocity increases, the diffusion coefficient experiences a decline, reaching a minimum at finite nonreciprocity. Under dense conditions and at low temperatures, the system undergoes a transition between the glassy and liquid states by modulating nonreciprocity. However, at high temperatures, nonreciprocity becomes less significant, and this transition cannot be achieved by changing nonreciprocity. Our findings shed light on the intricate interplay between particle interactions and system dynamics in the context of glass transition phenomena.

We report in situ single-molecule measurements of proton-induced double-strand breaks (DSBs) in DNA immersed in water, using real-time fluorescence tracking along the entire proton path, including the Bragg peak region. By chemically suppressing radical-mediated processes, we isolate direct DNA damage mechanisms and determine DSB cross sections as a function of depth. Near the Bragg peak, we observe a tenfold reduction in DSB cross sections in aqueous DNA compared to dry DNA, providing quantitative evidence for the protective role of water. These findings highlight the importance of intermolecular energy dissipation in mitigating radiation-induced damage in condensed biological matter, with implications for radiobiology and proton therapy modeling.

A simple scheme that could contribute to the construction of quantum double sources effectively is proposed and numerically verified. The scheme could be constructed by a four-wave-mixing system under a weak driving, in which the same-frequency single-photon and two-photon blockade effects could be realized simultaneously based on a blockade mechanism referred to as dressed-state-assisted photon blockade. The advantages of this mechanism over conventional and unconventional photon blockades are revealed, which could contribute to improve the purity and brightness of quantum bisources effectively. All of these make the construction of quantum bisource possible and would open a route to design simple and efficient quantum sources.

Trapped-ion qubits are among the most promising candidates for quantum computing, quantum information processing, and quantum simulation. In general, trapped ions are considered to have sufficiently long coherence times, which are mainly characterized under laser-free conditions. However, in reality, essential laser fields for quantum manipulation introduce residual light shift, which seriously degrades the coherence due to power fluctuations. Here, we present a comprehensive study of ac Stark shifts in the hyperfine energy levels of the ${}^{171}\mathrm{Yb}^{+}$ ion, revealing an asymmetric light shift between two circular polarizations in the clock qubit and pronounced vector light shifts in the Zeeman qubits. By precisely tuning these polarizations, a remarkable enhancement in coherence time is observed, reaching over a 100-fold for the clock qubit and more than 10-fold for the Zeeman qubits, when comparing conditions of maximum and minimum shifts. These findings advance the practical realization of scalable trapped-ion quantum processors, enabling deep quantum circuit execution and long-duration adiabatic operations.

The presence of topological defects in apolar chiral liquid crystals causes orientational distortions, leading to nonuniform strain. This nonuniform strain generates an electric polarization response due to the flexoelectric effect, which induces an internal electric field. Associated with this electric field is an electrostatic self-energy, which has a backreaction on the director field. Calculation of this internal electric field and its resulting backreaction on the director field is complicated. We propose a method to do such, adapting a method recently developed to study the magnetostatic self-interaction effect on skyrmions in chiral ferromagnets. Bloch skyrmions in chiral magnets are solenoidal and are unaffected by the magnetostatic self-interaction. However, Bloch skyrmions in liquid crystals yield nonsolenoidal flexoelectric polarization and, thus, are affected by the electrostatic self-interaction. Additionally, as the flexoelectric coefficients are increased in strength, a transition from a hopfion to a toron is observed in three-dimensional confined systems.