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Atom interferometry is proving to be one of the most precise technique in gravimetry and gravity gradiometry, measurements of gravitational acceleration and gravitation gradient, respectively, in addition to magnetometry, inertial sensing and many other fields. The high precision of these instruments has attracted applications in fundamental physics research. The potential of employing this technique for the searches in dark-sector physics initiated the building of an atom interferometer at the University of Liverpool. The interferometer is in an atomic drop configuration. It employs ultra-cold Rb-85 as the atomic medium and a two-laser optical system. The atom source loads about a hundred million Rb-85 atoms and cools them down to 15 ��K. The interferometric beams are generated with a high-frequency acoustic-optical modulator. The coherent control of atomic states was achieved via Raby oscillations, and atom interferometry has been demonstrated via Ramsey fringes with velocity-insensitive interferometric beams. This success provided an opportunity for building a new atom interferometer capable of velocity-sensitive measurements. The new interferometer will be able to operate in both atom launch and drop configurations and has the main vacuum chamber with 23 viewports, compared to 10 previously. This allowed for the incorporation of a low-velocity atom source. Two prototypes, 2D MOT and Axicon MOT, are being developed. A high power laser generating 8 W of 780 nm light via frequency doubling was built to increase the number of atoms. Such high powers necessitated a reconstruction of the optical control circuit, also allowing for atomic launch, improved state selection, and spurious light reduction. An effective vibration isolation system was constructed. Combining passive isolation and active cancellation technology in a working device was a significant step towards high sensitivity measurements. A new interferometry beam system was prospected, employing an injection-locked modulated laser diode. The prototype of such a system was built. The system proved to be capable of generating phase-locked light separated by 3 GHz. Later, due to concerns of stability and power limitations, a previous interferometry beam system was redesigned and improved instead. It employs additional tampered amplifiers to increase the power and a separate laser with an electro-optical modulator for the higher single-photon detuning, both required for velocity-sensitive measurements.

Cooling enhances the energy conversion efficiency and output of photovoltaic (PV) panels. In this work, the effects of natural convection, forced convection, and evaporative cooling on the performance of polycrystalline PV panels were investigated. The output and efficiency of a cooled PV panel were monitored and compared to those of an uncooled PV panel under the same conditions. The cooling was conducted using an insulated channel installed below a PV panel. Natural convection cooling was investigated for various channel air gaps (H = 30, 60, 90, and 120 mm). Natural convection currents in the cooling channels were capable of cooling the panel with wide air gaps. In forced convection cooling, the air was introduced by fans installed at the bottom opening of the cooling channel with various air velocities (ua = 1, 2, and 3 m/s). Evaporative natural convection cooling was performed by a wetted fabric along the lower surface of the cooling channel, whereas evaporative forced convection cooling by pushing air along the wetted lower surface of the channel. The experimental data showed that the panel efficiency and output increased due to cooling. The experimental results of natural convection cooling revealed that the use of an air gap of 120 mm to cool the solar panel contributed to an increase in the panel daily energy production and efficiency by 1.7% and 1.2%, respectively. For forced convection cooling, using air at a speed of 3 m/s increased the daily energy production by 4.4% and the efficiency by 4%. Natural convection evaporative cooling increased the daily energy production and the efficiency by 3.6% and 2.7%, respectively. Forced convection evaporative cooling contributed, at a speed of 2 m/s, to an increase in the daily energy production by 3.8% and an increase in efficiency of 3.8%.

In this manuscript, the chemi-ionization (CI) processes in atom - Rydberg atom collisions are examined. We obtained the cross-sections, as well as rate coefficients for CI processes in potassium and sodium collisions for principal quantum numbers 5⩽n⩽25 in the 500 K ⩽T⩽1500 K temperature region. The presented data could be useful for the improvement of analysis and modelling of weakly ionized layers of different atmospheres and cosmic objects where these and other CI processes could change excited state populations and the free electron density, consequently affecting the optical characteristics.

Ultralight scalar dark matter may induce apparent oscillations of the muon mass, which may be directly probed via temporal shifts in the spectra of muonium and muonic atoms. Existing datasets and ongoing spectroscopy measurements with muonium are capable of probing scalar-muon interactions that are up to 12 orders of magnitude more stringent than astrophysical bounds. Ongoing free-fall experiments with muonium can probe forces associated with the exchange of virtual ultralight scalar bosons between muons and standard-model particles, offering up to 5 orders of magnitude improvement in sensitivity over complementary laboratory and astrophysical bounds., Comment: 14 pages, 2 figures, version accepted for publication in PRL

We study the quantum interference between the excitation pathways in a three-level $\Lambda$-type atom interacting with two short laser pulse trains under the conditions of electromagnetically induced transparency. The probability amplitude equations which describe the interaction of a three-level $\Lambda$-type atom with two laser pulse trains are numerically solved. We derive analytical expressions for the population of the upper excited state for resonant laser pulse trains with a rectangular temporal profile. By varying the parameters of the laser pulse trains such as area of a single pulse, detuning, repetition period, and number of individual pulses, we analyze the quantum interference between the excitation pathways in terms of the upper excited state population.

We present an extension of the standard polarizable quantum mechanic/molecular mechanics (QM/MM) approach for treating environmental effects on excited state properties of embedded systems. A quantum polarizable atom model is derived from a full quantum description of the environment using perturbation theory for the system-environment coupling. Our model provides a more general description of the environment, including frequency dependent atomic polarizabilities, without loss of computational simplicity of the QM/MM approach. The classical polarizable atom description used in polarizable QM/MM approach can be obtained as a limiting case of the present model. This enables us to pinpoint approximations and assumptions about the system inherent to classical polarizable atom description of the environment. We apply our method to fluorographene (FG) based systems to investigate effects of the FG sheet on excited state properties of impurities on the FG surface. Comparison to full quantum chemistry calculations and to the standard polarizable QM/MM approach on disordered fluorograhene clusters reveals the importance of frequency dependence of atomic polarizabilities for the proper treatment of the effects of the environment on both the transition energy shifts and the interaction energies., 11 pages, 6 figures

For any distinct two primes $p_1\equiv p_2\equiv 3$ $(\text{mod }4)$, let $h(-p_1)$, $h(-p_2)$ and $h(p_1p_2)$ be the class numbers of the quadratic fields $\mathbb{Q}(\sqrt{-p_1})$, $\mathbb{Q}(\sqrt{-p_2})$ and $\mathbb{Q}(\sqrt{p_1p_2})$, respectively. Let $\omega_{p_1p_2}:=(1+\sqrt{p_1p_2})/2$ and let $\Psi(\omega_{p_1p_2})$ be the Hirzebruch sum of $\omega_{p_1p_2}$. We show that $h(-p_1)h(-p_2)\equiv h(p_1p_2)\Psi(\omega_{p_1p_2})/n$ $(\text{mod }8)$, where $n=6$ (respectively, $n=2$) if $\min\{p_1,p_2\}>3$ (respectively, otherwise). We also consider the real quadratic order with conductor $2$ in $\mathbb{Q}(\sqrt{p_1p_2})$., Comment: 19 pages

Hyperfine interactions between electron and nuclear spins have been widely used in material science, organic chemistry, and structural biology as a sensitive probe to the local chemical environment through spatial identification of nuclear spins. With the nuclear spins identified, the isotropic and anisotropic components of the hyperfine interactions in turn offer unique insight into the electronic ground-state properties of the paramagnetic centers. However, traditional ensemble measurements of hyperfine interactions average over a macroscopic number of spins with different geometrical locations and nuclear isotopes. Here, we use a scanning tunneling microscope (STM) combined with electron spin resonance (ESR) to measure hyperfine spectra of hydrogenated-titanium (Ti) atoms on MgO/Ag(100) and thereby determine the isotropic and anisotropic hyperfine interactions at the single-atom level. By combining vector-field ESR spectroscopy with STM-based atom manipulation, we characterize the full hyperfine tensor of individual Ti-47 and Ti-49 atoms and identify significant spatial anisotropy of hyperfine interaction for both isotopes when they are adsorbed at low-symmetry binding sites. Density functional theory calculations reveal that the large hyperfine anisotropy arises from a highly anisotropic distribution of the ground-state electron spin density. Our work highlights the power of ESR-STM-enabled single-atom hyperfine spectroscopy as a powerful tool in revealing ground-state electronic structures and atomic-scale chemical environments with nano-electronvolt resolution., 17 pages, 4 figures

The objective of the paper was to compare values of the muzzle brake efficiency coefficient for a rifle with active or inactive automatics systems. Special laboratory stand designed for investigating the recoil process was used. The motion of the rifle was detected by the use of the laser interferometer and the optical camera. The recoil velocity time courses were determined by smoothing and differentiation of experimental position records. The results of the experiments indicated that in the case of an active automatics system two values of the recoil velocity can be used for calculation of the energetic efficiency coefficient: the maximum recoil velocity and the final recoil velocity at the end of the automatics action cycle. The values of the coefficient, calculated using these two values of the recoil velocity, distinctly differ. However, it was shown that their values indicate the same relation between the efficiency of various muzzle brakes. The value of the efficiency coefficient, determined on the basis of the final recoil velocity value, is practically the same as that determined on the basis of the final recoil velocity value for the rifle with an inactive automatics system.

By using corks we construct diffeomorphic ribbon disks $D\subset B^{4}$, which are non-isotopic rel boundary to each other., Comment: 5 pages, 9 figures

Using the platform of a trapped-atom clock on a chip, we observe the time evolution of spin-squeezed hyperfine clock states in ultracold rubidium atoms on previously inaccessible timescales up to 1 s. The spin degree-of-freedom remains squeezed after 0.6 s, which is consistent with the limit imposed by particle loss and is compatible with typical Ramsey times in state-of-the-art microwave clocks. The results also reveal a surprising spin-exchange interaction effect that amplifies the cavity-based spin measurement via a correlation between spin and external degrees of freedom. These results open up perspectives for squeezing-enhanced atomic clocks in a metrologically relevant regime and highlight the importance of spin interactions in real-life applications of spin squeezing., 12 pages, 6 figures

Anomalous high-harmonic generation (HHG) arises in certain solids when irradiated by an intense laser field, as the result of a nonlinear perpendicular current akin to a Hall current. Here, we theoretically characterize the anomalous HHG mechanism, via development of an ab-initio methodology for strong-field laser-solid interaction that allows a rigorous decomposition of the total current. We identify two key characteristics of the anomalous harmonic yields: an overall increase with laser wavelength; and pronounced minima at certain intensities or wavelengths around which the emission time profiles drastically change. Such signatures can be exploited to disentangle the anomalous harmonics from the competing interband harmonics, and thus pave way for the experimental identification and time-domain control of pure anomalous harmonics., Comment: 7 pages, 4 figures

Alkali-metal atomic magnetometry is widely used due to its high sensitivity and cryogen-free operation. However, when operating in geomagnetic field, it suffers from heading errors originating from nonlinear Zeeman (NLZ) splittings and magnetic resonance asymmetries, which lead to difficulties in mobile-platform measurements. We demonstrate an alignment based $^{87}$Rb magnetometer, which, with only a single magnetic resonance peak and well-separated hyperfine transition frequencies, is insensitive or even immune to NLZ-related heading errors. It is shown that the magnetometer can be implemented for practical measurements in the geomagnetic environments and the photon-shot-noise-limited sensitivity reaches $9\,{\rm{fT}}/\sqrt{\rm{Hz}}$ at room temperature., 8 pages, 5 figures

In this paper, we study limiting embeddings of Besov-type and Triebel-Lizorkin-type spaces, $id_\tau: B_{p_1,q_1}^{s_1,\tau_1}(\Omega) \rightarrow B_{p_2,q_2}^{s_2,\tau_2}(\Omega)$ and $id_\tau : F_{p_1,q_1}^{s_1,\tau_1}(\Omega) \rightarrow F_{p_2,q_2}^{s_2,\tau_2}(\Omega)$, where $\Omega \subset \mathbb{R}^d$ is a bounded domain, obtaining necessary and sufficient conditions for the continuity of $id_\tau$. This can also be seen as the continuation of our previous studies of compactness of the embeddings in the non-limiting case. Moreover, we also construct Rychkov's linear, bounded universal extension operator for these spaces., Comment: 30 pages, no figures

We demonstrate an efficient optical guiding technique for coupling cold atoms in the near field of a planar nanophotonic circuit, and realize large atom-photon coupling to a whispering-gallery mode in a microring resonator with a single-atom cooperativity $C\gtrsim 8$. The guiding potential is created by diffracted light on a nanophotonic waveguide that smoothly connects to a dipole trap in the far field for atom guiding with subwavelength precision. We observe atom-induced transparency for light coupled to a microring, characterize the atom-photon coupling rate, extract guided atom flux, and demonstrate on-chip photon routing by single atoms. Our demonstration promises new applications with cold atoms on a nanophotonic circuit for chiral quantum optics and quantum technologies., 17 pages, 10 figures

Metric descriptions of gravitation, among them general relativity as today's established theory, are founded on assumptions summarized by the Einstein equivalence principle (EEP). Its violation would hint at unknown physics and could be a leverage for the development of quantum gravity. Atomic clocks are excellent systems to probe aspects of EEP connected to (proper) time and have evolved into a working horse for tests of local position invariance (LPI). Even though the operational definition of time requires localized and idealized clocks, quantum systems like atoms allow for spatial superpositions that are inherently delocalized. While quantum experiments have tested other aspects of EEP, no competitive test of LPI has been performed or proposed allowing for an intrinsic delocalization. We extend the concepts for tests of the universality of clock rates (one facet of LPI) to atom interferometry generating delocalized quantum clocks. The proposed test depends on proper time with a favorable scaling and is, in contrast to fountain clocks, robust against initial conditions and recoil effects. It enables optical frequencies so that the projected sensitivity exceeds the one of state-of-the-art localized clocks. These results extend our notion of time, detached from classical and localized philosophies., 11 pages, 4 figures, 1 table

We construct a pair of isotopic link configurations that are not thick isotopic while preserving total length., 2 pages, 1 figure

We introduce the concept of TRAP (Traces and Permutations), which can roughly be viewed as a wheeled PROP (Products and Permutations) without unit. TRAPs are equipped with a horizontal concatenation and partial trace maps. Continuous morphisms on an infinite dimensional topological space and smooth kernels (resp. smoothing operators) on a closed manifold form a TRAP but not a wheeled PROP. We build the free objects in the category of TRAPs as TRAPs of graphs and show that a TRAP can be completed to a unitary TRAP (or wheeled PROP). We further show that it can be equipped with a vertical concatenation, which on the TRAP of linear homomorphisms of a vector space, amounts to the usual composition. The vertical concatenation in the TRAP of smooth kernels gives rise to generalised convolutions. Graphs whose vertices are decorated by smooth kernels (resp. smoothing operators) on a closed manifold form a TRAP. From their universal properties we build smooth amplitudes associated with the graph., 52 pages, many figures. arXiv admin note: substantial text overlap with arXiv:2005.02115

Sympathetic cooling of a Fermi gas with a buffer gas of bosonic atoms is an efficient way to achieve quantum degeneracy in Fermi systems. However, all attempts to use this method for cooling ions until recently were ineffective because of the unremovable ion `"micromotion" in electromagnetic Paul traps, which prevents the realization of a number of hot projects with cold atom-ion systems. In this regard, we propose a new efficient method for sympathetic cooling of ions: the use for this purpose of cold buffer atoms in the region of atom-ion confinement-induced resonances (CIRs) [V.S. Melezhik, Phys. Rev. A103, 53109 (2021)]. We show that the destructive effect of "micromotion" on its sympathetic cooling can, however, be suppressed in the vicinity of the atom-ion CIR. Here, the resonant blocking of a close collision of an atom with an ion also resists its heating due to "micromotion". We investigate the effect of sympathetic cooling around CIRs in atom-ion, and atom-atom confined collisions within the quantum-quasiclassical approach using the Li-Yb$^+$ and Li-Yb confined systems as an example. In this approach, the Schr\"odinger equation for a cold light atom is integrated simultaneously with the classical Hamilton equations for a hotter heavy-ion or atom during a collision. We have found the region near the atom-ion CIR where the sympathetic cooling of the ion by cold atoms is possible in a hybrid atom-ion trap. We also show that it is possible to improve the efficiency of sympathetic cooling in atomic traps by using atomic CIRs., Comment: 8 pages, 4 figures, report on Int. Conf. on Pecision Physics and Fundamental Physical Constants (FFK2021) 4-8 October 2021, Stara Lesna, Slovakia. arXiv admin note: substantial text overlap with arXiv:2101.03565

The prospects of tests of CPT symmetry using precision spectroscopy of antihydrogen are discussed with special emphasis on the ground-state hyperfine structure, a measurement of which is the aim of the ASACUSA collaboration at the AD/ELENA facility of CERN. Ongoing parallel experiments using hyperfine spectroscopy of hydrogen and deuterium aiming at studying Lorentz invariance by determining coefficients of the Standard Model Extension framework are described., 8 pages 2 figures, Physics of Elementary Particles and Atomic Nuclei, in print, as part of the proceedings of the International Conference on Precision Physics and Fundamental Physical Constants, FFK2021

We consider the spectral gap of a uniformly chosen random $(d_1,d_2)$-biregular bipartite graph $G$ with $|V_1|=n, |V_2|=m$, where $d_1,d_2$ could possibly grow with $n$ and $m$. Let $A$ be the adjacency matrix of $G$. Under the assumption that $d_1\geq d_2$ and $d_2=O(n^{2/3}),$ we show that $\lambda_2(A)=O(\sqrt{d_1})$ with high probability. As a corollary, combining the results from Tikhomirov and Youssef (2019), we showed that the second singular value of a uniform random $d$-regular digraph is $O(\sqrt{d})$ for $1\leq d\leq n/2$ with high probability. Assuming $d_2$ is fixed and $d_1=O(n^2)$, we further prove that for a random $(d_1,d_2)$-biregular bipartite graph, $|\lambda_i^2(A)-d_1|=O(\sqrt{d_1})$ for all $2\leq i\leq n+m-1$ with high probability. The proofs of the two results are based on the size biased coupling method introduced in Cook, Goldstein, and Johnson (2018) for random $d$-regular graphs and several new switching operations we defined for random bipartite biregular graphs., Comment: 23 pages, 3 figures

International audience; The frequency chirping properties of silicon ring resonator modulators (RRMs) are experimentally investigated under sinusoidal modulation. The modulated electric field at the output of an RRM is measured in the time domain thanks to a coherent detection system. The power and phase waveforms are then analyzed in terms of their temporal phase and amplitude for different wavelength detunings between the optical source and the resonance and for different modulation frequencies. The evolution of the frequency chirp, described through a peak-to-peak chirp parameter, is quantified as a function of wavelength detuning and modulation frequency for the first time.

The Lamb dipole is a traveling wave solution to the two-dimensional Euler equations introduced by S. A. Chaplygin (1903) and H. Lamb (1906) at the early 20th century. We prove orbital stability of this solution based on a vorticity method initiated by V. I. Arnold. Our method is a minimization of a penalized energy with multiple constraints that deduces existence and orbital stability for a family of traveling waves. As a typical case, orbital stability of the Lamb dipole is deduced by characterizing a set of minimizers as an orbit of the dipole by a uniqueness theorem in the variational setting., Comment: 41 pages

In the centre of mass frame, we have studied theoretically the Z -boson resonant production in the presence of an intense laser field via the weak process e + e − → μ + μ − . Dressing the incident particles by a Circularly Polarized laser field (CP-laser field), at the first step, shows that for a given laser field’s parameters, the Z - boson cross section decreases by several orders of magnitude. We have compared the Total Cross Section (TCS) obtained by using the scattering matrix method with that given by the Breit-Wigner approach in the presence of a CP-laser field and the results are found to be very consistent. This result indicates that Breit-Wigner formula is valid not only for the laser-free process but also in the presence of a CP-laser field. The dependence of the laser-assisted differential cross section on the Centre of Mass Energy (CME) for different scattering angles proves that it reaches its maximum for small and high scattering angles. At the next step and by dressing both incident and scattered particles, we have shown that the CP-laser field largely affects the TCS, especially when its strength reaches 1 0 9 V . c m − 1 . This result is interpreted by the fact that heavy interacting particles require high laser field intensities to affect the collision’s cross section.

Significant leaps in the understanding of quantum systems have been driven by the exploration of geometry, topology, dimensionality, and interactions with ultracold atomic ensembles. A system where atoms evolve while confined on an ellipsoidal surface represents a heretofore unexplored geometry and topology. Realizing such an ultracold bubble system (potentially Bose-Einstein condensed) has areas of interest including quantized-vortex flow respecting topological constraints imposed by closed surfaces, new collective modes, and self-interference via free bubble expansion. Large ultracold bubbles, created by inflating smaller condensates, directly tie into Hubble-analog expansion physics. Here, we report observations from the NASA Cold Atom Lab facility aboard the International Space Station of bubbles of ultracold atoms created using a radiofrequency-dressing protocol. We observe a variety of bubble configurations of differing sizes and initial temperature, and explore bubble thermodynamics, demonstrating significant cooling associated with inflation. Additionally, we achieve partial coverings of bubble traps greater than 1 mm in size with ultracold films of inferred few-$\mu$m thickness, and we observe the dynamics of shell structures projected into free-evolving harmonic confinement. The observations are part of the first generation of scientific measurements made with ultracold atoms in space, exploiting the benefits of perpetual free-fall to explore gravity-free evolution of quantum systems that are prohibitively difficult to create on Earth. This work points the way to experiments focused on the nature of the Bose-Einstein condensed bubble, the character of its excitations, and the role of topology in its evolution; it also ushers in an era of orbital microgravity quantum-gas physics.

We prove the convergence of the density on the scale $Z^{-1}$ to the density of the Bohr atom (with infinitely many electrons) (strong Scott conjecture) for a model that is known to describe heavy atoms accurately.

OBJETIVES: To assess the effect of various factors on laser fiber tip degradation with the Thulium Fiber Laser (Tm-fiber): fiber stripping, adjustable laser settings (energy, frequency, peak power)...

Experimental data for the generation of optical frequency combs in magnesium fluoride microcavities with whispering gallery modes at 780 nm are presented. This wavelength corresponds to the normal group velocity dispersion for pumping by a laser diode operating in self-injection locking regime. It is shown that the excitation of frequency combs is caused both by the processes in the microresonator and by the processes in the laser diode. It is found that, in the self-injection locking regime, initially suppressed, longitudinal modes of the laser diode can be amplified, which leads to the generation of hybrid, laser-enhanced side components. As a result, combs with a highly effective conversion of pumping energy and a low level of phase noise are excited.

Evaporative cooling is a widely used energy-saving and environmentally friendly cooling technology. Evaporative cooling can be defined as a mass and heat transfer process in which the air is cooled by the evaporation of water and as a result a large amount of heat is transferred from the air to the water and thus the air temperature decreases. Evaporative cooling is mainly used in many cooling technologies used in buildings, factories, agricultural in addition to it is used industrially in cooling towers, evaporative condensers, humidification, and humidity control applications. Evaporative cooling is divided into direct evaporative cooling and indirect evaporative cooling, as well as water evaporative cooling and air evaporative cooling. This paper reviews the most important developments and technologies in evaporative cooling that lead to lower energy consumption and provide suitable cooling comfort.

Despite quantum electrodynamics (QED) being one of the most stringently tested theories underpinning modern physics, recent precision atomic spectroscopy measurements have uncovered several small discrepancies between experiment and theory. One particularly powerful experimental observable that tests QED independently of traditional energy level measurements is the `tune-out' frequency, where the dynamic polarizability vanishes and the atom does not interact with applied laser light. In this work, we measure the `tune-out' frequency for the $2^{3\!}S_1$ state of helium between transitions to the $2^{3\!}P$ and $3^{3\!}P$ manifolds and compare it to new theoretical QED calculations. The experimentally determined value of $725\,736\,700\,$$(40_{\mathrm{stat}},260_{\mathrm{syst}})$ MHz is within ${\sim} 1.7\sigma$ of theory ($725\,736\,252(9)$ MHz), and importantly resolves both the QED contributions (${\sim} 30 \sigma$) and novel retardation (${\sim} 2 \sigma$) corrections., Comment: Main text 6 pages, 4 figures, SI 21 pages 11 figures. Changed title from "Precision Measurement of the Helium $2^{3\!}S_1- 2^{3\!}P/3^{3\!}P$ Tune-Out Frequency as a Test of QED"

International audience; Finite element simulation modeling permits to predict hydrogen concentration for various initial boundary-values problems, but the results depend on the underlying transport mechanisms accounted for. Trapping process is a key factor in the apparent hydrogen diffusion, and the case of mobile traps as dislocations needs modification of the hydrogen transport equation usually considered in the literature. An extension of this model is proposed where hydrogen dragging by mobile traps is modeled by reaction-diffusion equations, involving trapping and detrapping kinetic, and is applied for evolving trap density with plastic strain. The consequences of trapped hydrogen mobility on diffusive hydrogen repartition in a reference Small Scale Yielding configuration are focused on, especially in term of acceleration of hydrogen transport. The potentiality of the model is illustrated by the modeling of the trapped hydrogen breakaway from fast moving dislocations.

application/pdf, Novel energy styles and energy productions are so required, hydrogen energy has been much attraction from the viewpoint of the environment. Many utilities of the hydrogen energy have been studied, and the industry studies of hydrogen production have also been done. In Fig. 1, it is shown that the facility of the hydrogen production in Jülich. The "Green hydrogen technologies" project has been demonstrated, and the hydrogen gas has been sourced continuously from solar heat. It has the advantage of storing sustainable "solar energy", which can be irradiated from the sun to the earth as the form of "hydrogen energy". So, it makes good sense to convert intermittently solar energy (clean energy) to hydrogen energy (clean energy). Considering these points, Kodama et al. has studied new energy production of the solar thermochemical production by an oxidation‐reduction reaction of the cerium oxide (CeO2, ceria). In Fig. 2, the hydrogen production facility uses the solar thermochemical process at Miyazaki University in Japan. The flow of hydrogen production is shown in Fig. 3. Then, the sunlight can be concentrated by many heliostats and converted to thermal energy. The hydrogen gas can be generated by the thermal redox reaction with control of the reaction temperature. Moreover, the redox reaction is the cycle reaction that consisted of two‐step reactions, which makes it possible to produce hydrogen gas efficiently. If the solar energy can be supplied stably, we can get hydrogen energy continuously.

Let $\mathfrak{g}$ be a finite-dimensional complex Lie algebra and $\textrm{HLie}_{m}(\mathfrak{g})$ be the affine variety of all multiplicative Hom-Lie algebras on $\mathfrak{g}$. We use a method of computational ideal theory to describe $\textrm{HLie}_{m}(\mathfrak{gl}_{n}(\mathbb{C}))$, showing that $\textrm{HLie}_{m}(\mathfrak{gl}_{2}(\mathbb{C}))$ consists of two 1-dimensional and one 3-dimensional irreducible components, and showing that $\textrm{HLie}_{m}(\mathfrak{gl}_{n}(\mathbb{C}))=\{\textrm{diag}\{\delta,\dots,\delta,a\}\mid \delta=1\textrm{ or }0,a\in\mathbb{C}\}$ for $n\geqslant 3$. We construct a new family of multiplicative Hom-Lie algebras on the Heisenberg Lie algebra $\mathfrak{h}_{2n+1}(\mathbb{C})$ and characterize the affine varieties $\textrm{HLie}_{m}(\mathfrak{u}_{2}(\mathbb{C}))$ and $\textrm{HLie}_{m}(\mathfrak{u}_{3}(\mathbb{C}))$. We also study the derivation algebra $\textrm{Der}_{D}(\mathfrak{g})$ of a multiplicative Hom-Lie algebra $D$ on $\mathfrak{g}$ and under some hypotheses on $D$, we prove that the Hilbert series $\mathcal{H}(\textrm{Der}_{D}(\mathfrak{g}),t)$ is a rational function., Comment: To appear in Linear and Multilinear Algebra

Coherent anti-Stokes Raman spectroscopy (CARS) and Ccherent anti-Stokes hyper-Raman spectroscopy (CAHRS), as other high-order nonlinear spectroscopy techniques, are widely exploited in many research fields, such as dynamic processes, gene expression spectrum screening, high-resolution spectroscopy, and nonlinear high-resolution imaging. However, it is difficult to make a quantitative analysis of the spectral signals that involve a large number of high-order micropolarizability tensors. It is reported that the CARS and CAHRS microscopic hyperpolarizability tensor elements can be decomposed into the product of the differentiation of Raman microscopic polarizability tensor α′i′j′ and hyper-Raman microscopic polarizability tensor β′i′j′k′ so that the high-order spectra can be simplified to the analysis of low-order spectra. In this paper, we use the bond additivity model (BAM) combined with experimental corrections to address the carbon dioxide (CO2) molecule and present the simplified scheme for differentiation of hyper-Raman microscopic polarizability tensor elements β′i′j′k′. Taking advantage of this approach, combined with the experimental correction, the differentiation of Hyper-Raman microscopic polarizability tensor elements β′i′j′k′ of the CO2 is obtained and the expressions of β′i′j′k′ for antisymmetric vibrations of CO2 are deduced. Finally, substituting the differentiation of Raman microscopic polarizability tensor elements α′i′j′ reported in the literature into the ratio above can obtain the proportional relationship between the microscopic polarizability tensor elements of CARS and CAHRS of the CO2. This method can provide the basis for the quantitative analysis of high-order nonlinear spectral profiles.

Femtosecond laser ablation is widely applied in high-precision machining of microholes in aeroengine turbine blades. To further explore the mechanism of action during the laser processing of microholes, numerical simulations were performed on the basis of a molecular dynamics (MD) method coupled with a two-temperature model (TTM). Laser irradiation on the surface of copper for different femtosecond-laser processing parameters is investigated in this work. Through the femtosecond-laser single-pulse central ablation simulation model, the laser energy flux density in a Gaussian laser spot range was discretized and analyzed to calculate the ablation depth at multiple points separately. The cross-sectional morphology of the femtosecond-laser single-pulse ablation pits was approximated and fitted. Finally, a 3D simulation model of the whole process of multiscale femtosecond-laser spiral processing microholes was established by superimposing multipulse femtosecond-laser spiral trajectories. This provides a theoretical basis for analyzing the evolution of geometric parameters and morphological characteristics of the hole during machining with specific laser and process parameters.

We investigate decay near boundary of the volume of sublevel sets in Cegrell classes of m − subharmonic function on bounded domains in ℂ n . On the reverse direction, some sufficient conditions for membership in certain Cegrell’s classes, in terms of the decay of the sublevel sets, are also discussed.

Ultracold atomic gases with the right balance of interactions enter a phase that demonstrates a superposition of seemingly opposing properties.

The replacement of hydrogen with conventional fossil fuel has been viewed as a feasible route to the ZERO emission transportation. Nowadays, the water electrolysis method has become mature and efficient enough to produce large-scale of hydrogen, and the condensation and reliquefaction technologies also greatly reduce the hydrogen loss via pipeline transmission, which both motivate the applications of hydrogen as a fuel. In this study, a combined power-hydrogen network is planned to supply the power demand of residential blocks and the charging/fueling demand for electrical vehicles and hydrogen vehicles, respectively. However, the joint scheduling of power-hydrogen network is challenging due to the non-linearity and non-convexity inherited from the hydraulic dynamics of hydrogen transmission. To resolve this problem, a convex-concave based sequential convex approximation method is proposed. A revised 37-bus system is used to demonstrate the validity of proposed method.

We study the sensitivity of a collisional single-atom probe for ultracold gases. Inelastic spin-exchange collisions map information about the gas temperature T or external magnetic field B onto the quantum spin-population of single-atom probes, and previous work showed enhanced sensitivity for short-time nonequilibrium spin dynamics [1]. Here, we numerically investigate the steady-state sensitivity of such single-atom probes to various observables. We find that the probe shows distinct sensitivity maxima in the (B, T ) parameter diagram, although the underlying spin-exchange rates scale monotonically with temperature and magnetic field. In parameter space, the probe generally has the largest sensitivity when sensing the energy ratio between thermal energy and Zeeman energy in an externally applied magnetic field, while the sensitivity to the absolute energy, i.e., the sum of kinetic and Zeeman energy, is low. We identify the parameters yielding sensitivity maxima for a given absolute energy, which we can relate to a direct comparison of the thermal Maxwell-Boltzmann distribution with the Zeeman-energy splitting. We compare our equilibrium results to nonequilibrium experimental results from a single-atom quantum probe, showing that the sensitivity maxima in parameter space qualitatively prevail also in the nonequilibrium dynamics, while a quantitative difference remains. Our work thereby offers a microscopic explanation for the properties and performance of this single-atom quantum probe, connecting thermodynamic properties to microscopic interaction mechanisms. Our results pave the way for optimization of quantum-probe applications in (B, T ) parameter space beyond the previously shown boost by nonequilibrium dynamics., Comment: 19 pages, 8 figures

We demonstrate a high-flux and low transverse temperature atomic beam of ytterbium by applying two-dimensional cooling using the ${}^1\mathrm{S}_0\text{-}{}^3\mathrm{P}_1$ intercombination transition to the cold atomic beam produced by the dipolar-allowed ${}^1\mathrm{S}_0\text{-}{}^1\mathrm{P}_1$ transition. The optimized transverse temperature of $11 \pm 9\,\mathrm{\mu K}$ and an atomic flux of $(7.5 \pm 1.0) \times 10^8\,\mathrm{atoms/s}$ are obtained for the atomic beam whose longitudinal velocity is $30\,\mathrm{m/s}$. The transverse temperature is maintained below $23\,\mathrm{\mu K}$, while the flux is above $6.5 \times 10^8\,\mathrm{atoms/s}$ in the longitudinal velocity range of $22 - 30\,\mathrm{m/s}$. We also discuss the feasibility of further narrowing the transverse momentum width to less than the recoil momentum using the momentum-selective optical transition between the ground state and the long-lived metastable state. The transverse momentum width of our atomic beam, which is narrower than 5.7 times the recoil momentum, is a good starting point for the proposed method., Comment: 7 pages, 6 figures

In this short paper, we review the Dirac equation on the zero-gravity Kerr-Newman spacetime. Our main objective is to provide a correspondence between the classification of the bound states for the zGKN spectrum and the usual hydrogenic states $1s_{1/2}$, $2s_{1/2}$, etc. of the Hydrogen atom., 13 pages. To appear in Int. J. Mod. Phys. D

For Majorana fermions the anapole moment is the only allowed electromagnetic multipole moment. In this work we calculate the anapole moment induced at one-loop by the Yukawa and gauge interactions of a Majorana fermion, using the pinch technique to ensure the finiteness and gauge-invariance of the result. As archetypical example of a Majorana fermion, we calculate the anapole moment for the lightest neutralino in the Minimal Supersymmetric Standard Model, and specifically in the bino, wino and higgsino limits. Finally, we briefly discuss the implications of the anapole moment for the direct detection of dark matter in the form of Majorana fermions., 24 pages, 8 figures, 1 table; published version

In this chapter, we look at the energy of electrons in an atom and determine how the quantum state of the atom changes over time. This leads us to introduce the energy operator, or Hamiltonian, and the Schrodinger equation that governs the behaviour of quantum systems. We show how light can interact with an atom, and as a demonstration of the quantum theory developed so far we explain how atomic clocks work.

We investigate the long-range, two-body interactions between rubidium and potassium atoms in highly excited ($n=70$) Rydberg states. After establishing properly symmetrized asymptotic basis states, we diagonalize an interaction Hamiltonian consisting of the standard Coulombic potential expansion and atomic fine structure to calculate electronic potential energy curves. We find that when both atoms are excited to either the $70s$ state or the $70p$ state, both the $\Omega=0+$ symmetry interactions and the $\Omega=0-$ symmetry interactions demonstrate a deep potential well capable of supporting many bound levels; the size of the corresponding dimer states are on the order of 2.25 $\mu$m. We estabish $n$-scaling relations for the equilibrium separation $R_e$ and the dissociation energy $D_e$ and find these relations to be consistent with similar calculations involving the homonuclear interactions between rubidium and cesium. We discuss the specific effects of $\ell$-mixing and the exact composition of the calculated potential well \textit{via} the expansion coefficients of the asymptotic basis states. Finally, we apply a Landau-Zener treatment to show that the dimer states are stable with respect to predissociation., Comment: 8 pages, 4 figures, 4 tables

We theoretically study the influence of laser polarization in inelastic scattering of electrons by hydrogen atoms in the presence of a circularly polarized laser field in the domain of field strengths below $10^{7}$ V/cm and high projectile energies. A semi-perturbative approach is used in which the interaction of the projectile electrons with the laser field is described by Gordon-Volkov wave functions, while the interaction of the hydrogen atom with the laser field is described by first-order time-dependent perturbation theory. A \textit{closed analytical solution} is derived in laser-assisted inelastic electron-hydrogen scattering for the $1s \to nl$ excitation cross section which is valid for both circular and linear polarizations. For the excitation of the $n=2$ levels simple analytical expressions of differential cross section are derived for laser-assisted inelastic scattering in the perturbative domain, and the differential cross sections by the circularly and linearly polarized laser fields and their ratios for one- and two-photon absorption are calculated as a function of the scattering angle. Detailed numerical results for the angular dependence and the resonance structure of the differential cross sections is discussed for the $1s \to 4l$ excitations of hydrogen in a circularly polarized laser field., Comment: arXiv admin note: text overlap with arXiv:1509.08695

We present a computer program to calculate the quantised rotational and hyperfine energy levels of diatomic molecules in the presence of dc electric, dc magnetic, and off-resonant optical fields. Our program is applicable to the bialkali molecules used in ongoing state-of-the-art experiments with ultracold molecular gases. We include functions for the calculation of space-fixed electric dipole moments, magnetic moments and transition dipole moments. Program summary Program Title: Diatomic-Py CPC Library link to program files: https://doi.org/10.17632/3yfxnh5bn5.1 Developer's repository link: https://doi.org/10.5281/zenodo.6632148 Licensing provisions: BSD 3-clause Programming language: Python ≥ 3.7 Nature of problem: Calculation of the rotational and hyperfine structure of molecules in the presence of dc magnetic, dc electric, and off-resonant laser fields. Solution method: A matrix representation of the Hamiltonian is constructed in the uncoupled basis set. Eigenstates and eigenenergies are calculated by numerical diagonalization of the Hamiltonian. Additional comments including restrictions and unusual features: Restricted to calculating the Stark and Zeeman shifts with co-axial electric and magnetic fields.

The fundamental concepts and principles of mechanics, or dynamics, were established in the 17th century. Copernicus gave the notion of reference system in 1543, and Galileo stated the principle of inertia in 1638 in his important work Discorsi e dimostrazioni mathematiche intorno a due nove scienze alla meccanica ed i movimenti locali.1 A particle on which no force is exerted has a constant velocity. Linear uniform motion is a state relative to the observer, and not a process. It is the variation of the velocity that is a process resulting from an external action. Many scientists participated in this evolution, such as Tycho Brahe, Kepler, Descartes, and Christiaan Huygens, to name a few.

We study the moduli space of frozen planet orbits in the Helium atom for an interpolation between instantaneous and mean interactions and show that this moduli space is compact., 17 pages

Physical review / A 105(3), 033111 (2022). doi:10.1103/PhysRevA.105.033111, We theoretically study orbital alignment in x-ray-ionized atoms and ions, based on improved electronic-structure calculations starting from the Hartree-Fock-Slater model. We employ first-order many-body perturbation theory to improve the Hartree-Fock-Slater calculations and show that the use of first-order-corrected energies yields significantly better transition energies than originally obtained. The improved electronic-structure calculations enable us also to compute individual state-to-state cross sections and transition rates and, thus, to investigate orbital alignment induced by linearly polarized x rays. To explore the orbital alignment of transiently formed ions after photoionization, we discuss alignment parameters and ratios of individual state-resolved photoionization cross sections for initially neutral argon and two exotic electronic configurations that may be formed during x-ray multiphoton ionization dynamics induced by x-ray free-electron lasers. We also present how the orbital alignment is affected by Auger-Meitner decay and demonstrate how it evolves during a sequence of one photoionization and one Auger-Meitner decay. Our present work establishes a step toward investigation of orbital alignment in atomic ionization driven by high-intensity x rays., Published by Inst., Woodbury, NY

Using helium-3 atom scattering, we have studied the adsorption kinetics, the structure and the diffusional dynamics of atomic hydrogen on the surface of a graphene monolayer on Ni(111). Diffraction measurements reveal a 4° rotated rectangular hydrogen overstructure. Hydrogen adsorption and desorption exhibit activation barriers of E a = ( 89 ± 7 ) meV and E d = ( 1.8 ± 0.2 ) eV, respectively. Helium-3 spin-echo measurements showed no decay of the spatial correlation function (or intermediate scattering function) within the time range of the spectrometer. Hence, we are able to set lower limits for a possible hydrogen surface diffusion rate.