Quantum scattering calculations for strongly interacting molecular systems are computationally demanding due to the large number of molecular states coupled by the anisotropy of atom-molecule interactions. We demonstrate that thermal rate coefficients for total (elastic $+$ inelastic) atom-molecule scattering are insensitive to the interaction anisotropy of the underlying potential energy surface. In particular, we show that the rate coefficients for ${\text{Rb-H}}_2$ and ${\text{Rb-N}}_2$ scattering at room temperature can be computed to 1% accuracy with anisotropy set to zero, reducing the complexity of coupled-channels quantum scattering calculations to numerical solutions of a single differential equation. Our numerical calculations and statistical analysis based on Gaussian process regression elucidate the origin and limitations of the invariance of the total scattering rate coefficients to changes in atom-molecule interaction anisotropy.

The quantum electrodynamic Araki-Sucher correction arising from the interaction between electrons and nuclei is calculated for rovibrational energy levels of the hydrogen molecule and its isotopologues. The corresponding expectation value $\langle r_{\mathrm{en}}^{-3}\rangle$ is evaluated across a wide range of internuclear distances using the Born-Oppenheimer approximation. The electronic wave function is represented as a linear combination of explicitly correlated Gaussian basis functions. This correction contributes approximately tenths of a megahertz (about ${10}^{-5}{\mathrm{cm}}^{-1}$) to the dissociation energy of rovibrational levels and to the transitions between them. Given recent spectroscopic measurements with an accuracy of 10 kHz, this correction is necessary to achieve sub-MHz agreement between theory and experiment.

The geomagnetic field encompasses a range of phenomena, from the slowly evolving main magnetic field over decades to the rapidly changing resonances of the Earth-ionosphere cavity, known as Schumann resonances (SRs), which oscillate at tens of cycles per second. Typically, the proportion of these components in the geomagnetic field is inversely related to their frequency. However, the rapidly changing components carry rich, real-time information about the Earth's spatial environment. In this work, we introduce a type of magnetometer, the finite-field alkali-noble-gas spin (FANS) magnetometer, designed to measure these weak signals with high sensitivity against geomagnetic background disturbances. The FANS magnetometer consists of two main components: a spin-based amplifier and an alkali-metal atomic magnetometer. The spin-based amplifier can amplify weak magnetic fields at specific frequencies by up to 70 times using highly polarized noble-gas spins. Furthermore, the alkali-metal atomic magnetometer is employed to measure the amplified signal and to provide a stable resonance field for the spin-based amplifier via a feedback system. We demonstrate a noise floor of $\sim 10{\text{fT/Hz}}^{1/2}$ while measuring simulated SR magnetic signals, effectively reducing common interference from the Earth's magnetic field. The FANS magnetometer exhibits remarkable anti-interference capabilities and provides a powerful tool to investigate geomagnetic physics.

We demonstrate that recent advances in QED theory of Li-like ions [V. A. Yerokhin, et al., Phys. Rev. A 112, 042801 (2025)] enable determinations of absolute nuclear charge radii for heavy elements. By incorporating constraints derived from electron-scattering data, we obtain radii that are independent of the assumed model of the nuclear charge distribution. Our approach is validated for ${}^{208}\mathrm{Pb}$, a well-studied spherical nucleus, and is then applied to ${}^{209}\mathrm{Bi}$, where low-lying nuclear excitations complicate the interpretation of muonic-atom data.

We report on the precision measurement of the unperturbed ${}^3{D}_1$ microwave transition frequencies in ${}^{176}\mathrm{Lu}^{+}$ to a fractional uncertainty of $4\times {10}^{-14}$. We find the $F=8$ to $F=7$ hyperfine transition frequency to be $10491519945.22882\left(38\right)\mathrm{Hz}$ and the $F=7$ to $F=6$ transition frequency to be $11290004289.88161\left(36\right)\mathrm{Hz}$. At this precision we are able to observe the hyperfine-mediated effects in the ratio of the quadrupole shifts, from which we can directly infer the residual quadrupole moment after ${}^{3}D_1$ hyperfine averaging. We find a residual quadrupole moment of $-2.48\left(23\right)\times {10}^{-4}e{a}_0^2$, consistent with a previous assessment using a different and less direct method. With the unperturbed microwave frequencies accurately known, the residual quadrupole shift for a ${}^{176}\mathrm{Lu}^{+}$ (${}^{3}D_1$) optical frequency standard can henceforth be readily evaluated to $<{10}^{-20}$ uncertainty by routine ${}^3{D}_1$ microwave spectroscopy.

We report measurements and theoretical calculations of the fine-structure splittings in all three $1s2s{}^{3}S_1\to 1s2p{}^{3}P_{0,1,2}$ transitions in the heliumlike systems of the isotopes ${}^{12,13,14}\mathrm{C}$. The metastable triplet state was efficiently populated in an electron beam ion source and the ${\mathrm{C}}^{4+}$ ions were electrostatically accelerated to 50 keV to perform collinear laser spectroscopy. From the determined transition frequencies, the splitting isotope shift (SIS), i.e., the difference in fine-structure splittings between different isotopes of the same element, was extracted. In the SIS, theoretical uncertainties due to higher-order quantum electrodynamic corrections are strongly suppressed since they are independent of both nuclear mass and the fine-structure quantum number $J$ in lowest order. Comparison with theory provides an important test of experimental accuracy, particularly in the ${}^{13}\mathrm{C}^{4+}$ case, for which the nuclear spin leads to hyperfine-induced fine-structure mixing. At the same time, the even-even isotopes ${}^{12,14}\mathrm{C}^{4+}$ without nuclear spin can be used to confirm theory. Theoretical values of the SIS are given for all the heliumlike ions with $2\le Z\le 10$.

This paper presents a theoretical study of the light-induced shift of the coherent population trapping resonance. An analytical model is proposed that describes the interaction of two radiation components with an atomic system using a $\mathrm{\Lambda }$ scheme and takes into account an additional level of excited state. Both weak and strong coupling regimes with off-resonant transitions are considered. It is shown that, in addition to the conventional dynamic Stark shift, an extra shift arises due to the distortion of the resonance line shape when bichromatic laser radiation interacts with off-resonant atomic transitions. An analytical expression for this additional shift is derived in the weak-coupling limit, and its significant impact on the resonance shape and sensitivity to the intensities of the laser field components is demonstrated. It is found that under strong coupling conditions, the additional shift can deviate substantially from a linear dependence on light intensity, suggesting new opportunities for controlling light shifts in precision atomic devices such as quantum frequency standards.

We investigate plasmon-assisted photoelectron emission using a one-dimensional time-dependent density-functional theory model. The plasmons are excited nonlinearly by three laser photons. Photoelectron spectra are computed with the time-dependent surface-flux method. In addition to the expected above-threshold ionization comb, we observe peaks that arise from long-lived plasmon oscillations and the associated electron emission occurring after the laser pulse. We further analyze the positions of these peaks and their scaling behavior with the laser intensity.

Highly efficient quantum memories are essential for advancing quantum information processing technologies, including scalable quantum computing and quantum networks. We experimentally demonstrate a light storage and retrieval protocol in a tripod system using an ensemble of laser-cooled ${}^{87}\mathrm{Rb}$ atoms. The tripod system, which consists of three ground states and an excited state, offers rich dynamics: its use to coherently store and retrieve a weak probe pulse in the ${}^{87}\mathrm{Rb} F=1$ ground-state manifold leads to the interference of two spin-wave excitations during storage time that translate to an interference in the peak intensity of the retrieved probe pulse. Our work shows that these interferences, which manifest when varying the pulse sequence or energy level structure, can be controlled experimentally by varying the storage time, optical phase, and magnetic field strength. Theoretical simulations exhibit excellent agreement with the experimental results. This work demonstrates the rich dynamics and versatile capabilities of atomic tripod systems for light storage and retrieval, with key advantages over conventional $\mathrm{\Lambda }$ systems, highlighting the potential of atomic tripod systems for applications in quantum information processing, quantum synchronization, and atomic memory protocols.

We report high-resolution slow-electron velocity-map imaging (SEVI) of cryogenically cold $\mathrm{Se}{\mathrm{H}}^{-}$ and $\mathrm{Te}{\mathrm{H}}^{-}$ anions. The resolved rotational structures are well reproduced by our photodetachment rotational simulations, yielding highly accurate electron affinities (EAs) of 2.212 523(27) eV for SeH, and 2.107 686(35) eV for TeH, improving the precision by a factor of more than 400 for TeH. This work demonstrates an effective approach for precisely determining electron affinities and molecular constants by combining high-resolution cryo-SEVI spectroscopy with photodetachment rotational simulations. The accurate experimental data provide benchmarks for theoretical calculations of these heavy hydrides.

Electric and magnetic fields are inherently coupled in an electromagnetic wave. However, structured light beams enable their spatial separation. In particular, azimuthally polarized laser beams exhibit a localized magnetic field on-axis without the electric counterpart. A recent study by Martín-Domene et al. [S. Martín-Domene et al., Appl. Phys. Lett. 124, 211101 (2024)] has shown that combining these beams enables the generation of locally isolated magnetic fields with a controllable direction and phase. In the present paper, we propose a method to probe and characterize such magnetic fields by studying their interaction with a single trapped atom. In order to theoretically investigate magnetic sublevel populations and their dependence on the relative orientation and phase—i.e., the polarization state—of the isolated magnetic field, we use a time-dependent density-matrix method based on the Liouville–von Neumann equation. As illustrative cases, we consider the $2s^{2}2p^2{}^{3}P_0-2s^{2}2p^2{}^{3}P_1$, $1s^{2}2s^2{}^{1}S_0-1s^{2}2s2p{}^{3}P_2$, and $2s^{2}2p{}^{2}P_{1/2}-2s^{2}2p{}^{2}P_{3/2}$ transitions in ${}^{40}\mathrm{Ca}^{14+}$, ${}^{10}\mathrm{Be}$, and ${}^{38}\mathrm{Ar}^{13+}$, respectively. Our results indicate that monitoring atomic populations serves as an effective tool for probing isolated vector magnetic fields, which opens avenues for studying laser-induced processes in atomic systems where electric-field suppression is critical.

We investigate a one-dimensional three-component few-fermion mixture confined in a parabolic external trap, where one component contains a single particle acting as an impurity. Focusing on the many-body ground state, we analyze how the interactions between the impurity and the other components influence the system's structure. For fixed interaction strengths within the mixture, we identify a critical interaction strength with the impurity for which the system undergoes a structural transition characterized by a substantial change in its spatial features. We explore this transition from the point of view of correlations and ground-state susceptibility. We find that this transition exhibits unique universality features not observed in other systems, highlighting novel many-body properties existing in multicomponent fermionic mixtures.

We theoretically investigate the correlated decoherence dynamics of two mobile impurities trapped within a gas of ultracold fermionic atoms. We use a mean-field approximation to self-consistently describe the effect of impurity-gas collisions on impurity motion, while decoherence of the impurities' internal state is computed exactly within a functional determinant approach. At equilibrium, we find that the impurities undergo bath-induced localization as the impurity-gas interaction strength is increased. We then study the nonequilibrium dynamics induced by a sudden change of the impurities' internal state, which can be experimentally probed by Ramsey interferometry. Our theoretical approach allows us to investigate the effect of impurity motion on decoherence dynamics, finding strong deviations from the universal behavior associated with Anderson's orthogonality catastrophe when the mass imbalance between impurity and gas atoms is small. Finally, we show that mobile impurities can be used as thermometers of their environment, and that bath-mediated correlations can be beneficial for thermometric performance at low temperatures, even in the presence of nontrivial impurity motion. Our results showcase the interesting open quantum dynamics of mobile impurities dephasing in a common environment, and they can help to provide more precise temperature estimates of ultracold fermionic mixtures.

We present a comprehensive theoretical investigation of the damping of the monopole mode in strongly interacting Fermi gases confined close to spherical symmetry. Within a hydrodynamic scaling framework, we systematically account for deviations from ideal conditions, including trap anisotropy, anharmonicity, and finite detuning from unitarity. By treating these effects perturbatively, we derive analytical expressions for frequency shifts and damping rates of collective modes. Our analysis reveals that trap-induced symmetry breaking and interaction-induced corrections constitute the primary damping mechanisms, arising from mode coupling between monopole and quadrupole excitations. The results establish a unified theoretical framework that quantitatively captures recent observations of long-lived breathing oscillations and clarify the roles of geometry and interactions in shaping collective dynamics of strongly correlated quantum gases.

We consider a bimodal light field envelope propagating in a bulk medium characterized by competing cubic and quintic nonlinearities. The two components are coupled by a cross-phase-modulation term and experience effective attraction. We find dynamically stable stationary states which have two distinct flattop regions with different intensities. These solutions represent half-vortices, where the first and second components are essentially different and in particular carry different topological charges: zero for one component and nonzero for the other. The typical propagation of an unstable half-vortex leads to the splitting of the central vortex core into several fragments which quasielastically interact with the boundary of the flattop region. This behavior is interpreted as a self-bound solitary-wave billiard, where the emerging fragments are the billiard balls and the flattop region is the dynamically deforming table.

We propose an effective method for cooling two nondegenerate mechanical resonators by routing thermal noise flow in a four-mode optomechanical plaquette. The thermal noise flow between the mechanical resonators can be fully suppressed by addressing the overall loop phase in the plaquette, irrespective of their thermal temperatures. We find that optimal mechanical cooling, even down to the ground state, can be realized in this regime. The thermal noise routing, achieved by dissipation engineering at optomechanical interfaces, provides a powerful and complementary approach to conventional coherent dark-mode control theory. It can be generalized to nonreciprocal control of phonon transport and mechanical cooling and may find applications in optomechanical networks with complex thermal environments.

We propose a reconfigurable chiral optomechanically induced Faraday (OMIF) effect in a multimode optomechanical system (OMS), achieving near-absorption-free polarization control. Balanced gain and loss between two MRs establishes quantum destructive interference in two different exciting paths that suppresses the OMIF effect at resonance while enabling lossless polarization conversion at sidebands. The mechanical coupling phase generates synthetic magnetic flux, which selectively controls hybridized mechanical modes and breaks time-reversal symmetry, leading to significant spectral asymmetry and chirality. Coherent mechanical driving further enhances this asymmetry in the dark-mode unbroken (DMU) regime and enables directional control of the chiral optical response in the dark-mode broken (DMB) regime. Crucially, this approach requires neither strong pump fields nor intrinsic magnetic materials, as the nonreciprocal response originates purely from interference and phase engineering. Our work provides a scalable, low-loss platform for on-chip polarization logic devices and chiral integrated photonics.

We consider a type of hypothetical compound materials in which its refractive index in spatial distribution meets $n(-x)=-n^{*}\left(x\right)$, belonging to anti-parity-time- ($\mathrm{A}\mathcal{PT}$) symmetric structures. Additionally, we demand balanced real positive and negative permeabilities with $\mu (-x)=-\mu \left(x\right)$. By introducing parametrization into an $\mathrm{A}\mathcal{PT}$-symmetric transfer matrix, together with a reciprocity theorem, we propose a generic parametric space to display its associated scattering results such as symmetry phase, exceptional point (EP), and symmetry-broken phase. The outcome is irrespective of any system complexity, geometries, materials, and operating frequency. With the parametric space, we find that an $\mathrm{A}\mathcal{PT}$-symmetric system not only enables coherent perfect absorption or lasing occurring at an exceptional point, but also realizes a simultaneous coherent perfect absorption and lasing. Since an $\mathrm{A}\mathcal{PT}$-symmetric system is constructed by balanced positive and negative index materials, the phase accumulated from an optical path length is null, resulting in a real transmission coefficient and an assignment of mode order lost. Although it is challenging to realize negative index materials, a dielectric heterostructure with mirror symmetry is proposed to effectively mimic the electromagnetic responses. Several all-dielectric heterostructures with coherent perfect absorption at an EP, lasing at an EP, and coherent perfect absorption lasing are demonstrated to support our findings on $\mathrm{A}\mathcal{PT}$-symmetric systems.

The dynamics of electrically pumped nanolaser arrays is analyzed within the framework of non-Hermitian photonics. By employing a small-signal analysis, general features of the dynamics including parity-time symmetry analogous behavior and exceptional points are extracted. Qualitative features of the device dynamics are revealed in the vicinity of exceptional points. It is shown that nanolasers, characterized by Purcell-enhanced spontaneous emission, manifest periodic dynamics while analogous lasers with no Purcell enhancement exhibit chaotic dynamics. The opportunity for utilizing such laser arrays for exploring the ramifications of non-Hermitian photonics is noted.

Higher-order photonic modes have the potential to achieve superior absorption enhancement in inverse opal photocatalysts, beyond conventional blue or red edge slow light modes. This study reports a finite element method, numerical investigation of ${\mathrm{TiO}}_2$ inverse opals with an ultrathin material skeleton and varying diameters of interconnected pores, at different angle of incidence. Both diameter and angle variations are used to tune slow light modes to the ${\mathrm{TiO}}_2$ electronic band edge in the near-UV. In the case of air-filled pores, relevant to gas-phase photocatalysis, for a pore diameter of 240 nm, at normal incidence, the absorption enhancement factor reached a maximum value of $\alpha =2.07$ thanks to tuning of the fifth allowed mode of the band structure. By contrast, for pore diameters corresponding to red (blue) edge tuning, an enhancement factor of only $\alpha =1.18$ ($\alpha =1.97$) could be achieved at normal incidence. Tighter confinement of the fifth mode into the skeleton is responsible for this enhanced performance. At ${45}^{\circ }$ oblique incidence, tuning of that mode leads to even further enhancement ($\alpha =2.42$) due to better coupling and light trapping caused by the nonzero in-plane component of the wave vector. In the case of water-filled pores, relevant to liquid-phase photocatalysis, for a pore diameter of 280 nm at normal incidence, the enhancement factor ($\alpha =2.39$) greatly outperforms blue edge tuning ($\alpha =1.62$) thanks to the tuning of the allowed modes from ninth to 15th of the band structure. We believe our study will offer additional insights into exploiting slow light effects in inverse opals for photocatalysis, and more generally, solar energy conversion applications.