Atomic Physics Research Articles

Parity violation in resonant inelastic soft x-ray scattering at entangled core holes.

Resonant inelastic x-ray scattering (RIXS) is a major method for investigation of electronic structure and dynamics, with applications ranging from basic atomic physics to materials science. In RIXS applied to inversion-symmetric systems, it has generally been accepted that strict parity selectivity applies in the sub-kilo-electron volt region. In contrast, we show that the parity selection rule is violated in the RIXS spectra of the free homonuclear diatomic O2 molecule. By analyzing the spectral dependence on scattering angle, we demonstrate that the violation is due to the phase difference in coherent scattering at the two atomic sites, in analogy with Young's double-slit experiment. The result also implies that the interpretation of x-ray absorption spectra for inversion symmetric molecules in this energy range must be revised.

CIRCUS: an autonomous control system for antimatter, atomic and quantum physics experiments

A powerful and robust control system is a crucial, often neglected, pillar of any modern, complex physics experiment that requires the management of a multitude of different devices and their precise time synchronisation. The AEḡIS collaboration presents CIRCUS, a novel, autonomous control system optimised for time-critical experiments such as those at CERN’s Antiproton Decelerator and, more broadly, in atomic and quantum physics research. Its setup is based on Sinara/ARTIQ and TALOS, integrating the ALPACA analysis pipeline, the last two developed entirely in AEḡIS. It is suitable for strict synchronicity requirements and repeatable, automated operation of experiments, culminating in autonomous parameter optimisation via feedback from real-time data analysis. CIRCUS has been successfully deployed and tested in AEḡIS; being experiment-agnostic and released open-source, other experiments can leverage its capabilities.

Expanding gain bandwidth using ion-hybridized fiber for kHz-linewidth single-frequency fiber lasers at S-, C-, and L-bands: design and performance evaluation.

Single-frequency fiber lasers at S-, C-, and L-bands play a crucial role in various applications such as optical network expansion, high-precision metrology, coherent lidar, and atomic physics. However, compared to the C-band, the S- and L-bands have wavelength deviations and suffer from excited-state absorption, which limits the output performance. To address this issue, a strategy called ion hybridization has been proposed to increase the differences in site locations of rare earth (RE) ions in the laser matrix, thereby achieving a broader gain bandwidth. This strategy has been applied to an Er3+/Yb3+ co-doped modified phosphate fiber (EYMPF), resulting in gain coefficients per unit length greater than 2 dB/cm at S-, C-, and L-bands. To demonstrate its capabilities, several centimeter-long EYMPFs have been used to generate single-frequency laser outputs at S-, C- and L-bands with kHz-linewidths, high signal-to-noise ratios (>70 dB), and low relative intensity noise (<-130 dB/Hz) in a compact short linear-cavity configuration.

Testing He ii Emission from Wolf–Rayet Stars as a Dust Attenuation Measure in Eight Nearby Star-forming Galaxies

The ability to determine galaxy properties such as masses, ages, and star formation rates robustly is critically limited by the ability to measure dust attenuation accurately. Dust reddening is often characterized by comparing observations to models of either nebular recombination lines or the UV continuum. Here, we use a new technique to measure dust reddening by exploiting the He ii λ1640 and λ4686 emission lines originating from the stellar winds of Wolf–Rayet stars. The intrinsic line ratio is determined by atomic physics, enabling an estimate of the stellar reddening similar to how the Balmer lines probe gas-emission reddening. The He ii line ratio is measured from UV and optical spectroscopy using the Space Telescope Imaging Spectrograph on board the Hubble Space Telescope for eight nearby galaxies hosting young massive star clusters. We compare our results to dust reddening values estimated from UV spectral slopes and from Balmer line ratios and find tentative evidence for systematic differences. The reddening derived from the He ii lines tends to be higher, whereas that from the UV continuum tends to be lower. A larger sample size is needed to confirm this trend. If confirmed, this may indicate an age sequence probing different stages of dust clearing. Broad He ii lines have also been detected in galaxies more distant than in our sample, providing the opportunity to estimate the dust reddening of the youngest stellar populations out to distances of ∼100 Mpc.

Atoms Dressed by Virtual and Real Photons

Specific properties of quantum field theory are described by considering the combination of the system under investigation and the cloud of virtual or real particles associated with the field. Such a structure is called a “dressed system”, in contrast with the bare one in the absence of the interaction with the field. The description of the properties of such clouds in various physical situations is, today, an active research area. Here, we present the main features associated with virtual and real dressings, focusing on photon dressing. In analogy to virtual photon clouds dressing electrons in vacuum, virtual phonon clouds appear in solid-state physics. The interaction between real photons and the schematized two-level structure of an atom paves the way to flexible quantum control. Here, a unifying Floquet engineering approach is applied to describe single- and multiple-dressed atom configurations. Connections with the past and present atomic physics experiments are presented.

Toward constraint of ionization-potential depression models in a convergent geometry

We demonstrate the value of inner-shell X-ray absorption spectroscopy for dense-plasma atomic physics and explore the coupling between constraint of the thermodynamic state and constraint of ionization-potential depression models. Synthetic K-shell absorption spectra are generated along a radius from a point-like core and analyzed using different ionization-potential depression models. Within this synthetic analysis framework, we identify plasma conditions (Te=400 eV, ρ=40 g/cm3) accessible by spherical implosions where K-shell absorption spectra discriminate between models if the material temperature is measured to a precision of 20%. The analysis is extensible to a finite-sized core and can be used to guide future studies of ionization-potential depression, informing material and radiative properties of matter in fusion plasmas and stellar interiors.

Precise measurements of electron &lt;i&gt;g&lt;/i&gt; factors in bound states of few-electron ions

&lt;sec&gt;The electron &lt;i&gt;g&lt;/i&gt; factor is an important fundamental structural parameter in atomic physics, as it reveals various mechanisms of interactions between electrons and external fields. Precise measurements of &lt;i&gt;g&lt;/i&gt; factors of bound electrons in simple atomic and molecular systems provide an effective method for investigating the bound-state quantum electrodynamics (QED) theory. Especially in highly-charged heavy ions (HCIs), the strong electromagnetic interactions between the nuclei and inner-shell electrons provide unique opportunities to test QED under extremely strong fields. Accurate measurements of the &lt;i&gt;g&lt;/i&gt; factors of the bound-state electrons are also important for determining nuclear effects, nuclear parameters and fundamental constants. The research on &lt;i&gt;g&lt;/i&gt; factors of the bound-state electrons has become a frontier topic in fundamental physics. A Penning trap, which uses steady-state electromagnetic fields to confine charged particles, is utilized to precisely measure the &lt;i&gt;g&lt;/i&gt; factor. This paper presents a comprehensive review of the experiments on &lt;i&gt;g&lt;/i&gt; factors for few-electron simple systems in Penning traps, including experimental principles, experimental setups, measurement methods, and a summary of important research findings. The physical concept of the electron &lt;i&gt;g&lt;/i&gt; factor and its historical research background are introduced. The electron &lt;i&gt;g&lt;/i&gt; factor is considered as an effective probe to study higher-order QED effects. Through high-precision measurements of the free electron g factor, discrepancies between the fine-structure constants and other experimental results in atomic physics are identified. Notably, the &lt;i&gt;g&lt;/i&gt; factor of the 1s electron in HCIs deviates significantly from the value for free electrons as the atomic number increases. Experimental principles, including the principle of the Penning trap and the principle of measuring the bound-state electron &lt;i&gt;g&lt;/i&gt; factors are discussed. A double-trap experiment setup and related precision measurement techniques are also introduced.&lt;/sec&gt;&lt;sec&gt;This paper reviews several milestone experiments including (1) the stringent test of bound-state QED by precise measurement of bound-state electron &lt;i&gt;g&lt;/i&gt; factor of a &lt;sup&gt;118&lt;/sup&gt;Sn&lt;sup&gt;49+&lt;/sup&gt; ion, (2) measurement of the &lt;i&gt;g&lt;/i&gt; factors of lithium-like and boron-like ions and their applications, and (3) measurement of the &lt;i&gt;g&lt;/i&gt;-factor isotope shift by using an advanced two-ion balance technique in the Penning trap, providing an insight into the QED effects in nuclear recoil. Finally, this paper summarizes the challenges currently faced in measuring the &lt;i&gt;g&lt;/i&gt; factors of bound-state electrons in few-electron ion systems and provides the prospects for the future developments of this field.&lt;/sec&gt;

Squeezing and evolution of single particle by frequency jumping in two-dimensional rotating harmonic

The control of microscopic particle behavior based on a specific external field has always been a research hotspot in the field of physics. Many studies have been exploring various methods to manipulate and control the behavior of particles at a microscopic level. In this work, we investigate the phenomenon of single-particle squeezing induced by frequency jumping in a two-dimensional rotating harmonic oscillator potential. Squeezing, as a quantum mechanical phenomenon, has attracted significant attention due to its potential applications in various fields. It refers to the reduction of fluctuations in certain physical quantities, allowing for more precise measurement results. Squeezing phenomena have been extensively studied in different physical systems, including optics, atomic physics, and solid-state physics. However, there have been few reports on the quantum state squeezing phenomenon induced by frequency jumping in a rotating harmonic oscillator potential. Therefore, our study aims to fill this gap and shed light on this intriguing phenomenon. To explore the squeezing phenomenon induced by frequency jumping, we focus on the fluctuations and squeezing of the single particle’s cyclotron radius coordinate and center-guided coordinate in the two-dimensional rotating harmonic oscillator potential. Through numerical simulations and theoretical analysis, we can understand the influence of frequency jumping on the degree of squeezing and reveal the underlying physical mechanism of squeezing evolution. In this work, we first investigate the influence of frequency jumping on the squeezing evolution of the cyclotron radius mode. By carefully selecting appropriate jumping moments, we analyze the influence of frequency jumping on the degree of squeezing. Our research results show that the degree of squeezing in the cyclotron radius coordinate remains unchanged at the jumping moment. However, we observe a stronger squeezing phenomenon in the subsequent evolution process. This indicates that frequency jumping plays a crucial role in squeezing evolution of the cyclotron radius mode. Furthermore, we focus on the squeezing evolution of the center-guided mode during frequency jumping. By selecting suitable parameters, we analyze the squeezing and evolution of two squeezing modes: the divergent mode and the oscillatory mode. Interestingly, we discover the existence of a critical potential trap aspect ratio, which is determined by the rotation angular velocity of the external potential. When the aspect ratio approaches this critical value, the squeezing mode undergoes a transition, and a significant squeezing phenomenon appears in the oscillatory mode. This finding provides valuable insights into the origin and control of squeezing phenomena. Finally, we discuss the potential applications of these squeezing phenomena. Squeezing has significant implications in the fields of quantum sensing and quantum information processing. Through a deeper understanding of the squeezing evolution process caused by frequency jump, we can better control the microscopic particle behavior through external field. This knowledge opens up new possibilities for future physical research and technical applications.

Superheavy nuclei and other exotics – opportunities at SPIRAL2 and S3

The structure of very heavy and superheavy nuclei (SHN) as well as the location of the next proton and neutron shell closures beyond 208Pb is still one of the most intriguing topics in modern nuclear physics [1]. Worldwide competitive, high beam intensities provided by the accelerator facility SPIRAL2 at GANIL which started operation recently, will cover in future all ions up to uranium thanks to the new injector project NEWGAIN. Combined with the separator-spectrometer installation S3 [3], it will provide the instrumental prerequisites for an ambitious science program. Apart from SHN/SHE research, the envisaged physics case at S3 covers, among other, the structure of N=Z nuclei, low energy physics (fundamental properties of the atomic nucleus etc.), interdisciplinary research, atomic physics and reaction studies (fission, deep inelastic reactions etc.). The state of the art of the field is discussed in this paper with an emphasis on the role of the odd particle(s) in odd-even, even-odd and odd-odd nuclei and the consequences for nuclear structure features like K-isomers, trends of single-particle energies as a function of deformation, and the competition of spontaneous fission (SF) and α decay. As an alternative approach to produce heavy and in particular more neutron-rich nuclear species multi-nucleon transfer reactions are briefly discussed as well.

Attosecond science the art of making electron movies

After 22 years since the first experimental demonstration of attosecond pulses, the attosecond science has become a very active field of research, with prominent applications in atomic, molecular and solid-state physics. Experimental advances, in terms of new sources, devices and techniques, are still required, together with new theoretical tools and approaches, but attosecond physics has firmly established as a mature research field.

Dissociation of chlorobromomethane molecules coherently regulated by ultrafast strong field

Coherent control of molecular dissociation in ultrafast strong fields has received considerable attention in various scientific disciplines, such as atomic and molecular physics, physical chemistry, and quantum control. Many fundamental issues still exist regarding the understanding of phenomena, exploration of mechanisms, and development of control strategies. Recent progress has shown that manipulating the spectral phase distribution of a single ultrafast strong ultraviolet laser pulse while maintaining the the same spectral amplitude distribution can effectively control the total dissociation probability and branching ratios of molecules initially in the ground state. In this work, the spectral phase control of the photodissociation reaction of chlorobromomethane (CH&lt;sub&gt;2&lt;/sub&gt;BrCl) is studied in depth by using a time-dependent quantum wave packet method, focusing on the influence of the initial vibrational state on the dissociation reaction. The results show that modifying the spectral phase of a single ultrafast pulse does not influence the total dissociation probability or branching ratio in the weak field limit. However, these factors exhibit significant dependence on the phase of the single ultrafast pulse spectrum under the strong field limit. By analyzing the population distribution of vibrational states in the ground electronic state, we observe that chirped pulses can effectively regulate the resonance Raman scattering (RRS) phenomenon induced in strong fields, thereby selectively affecting the dissociation probability and branching ratio based on initial vibrational states. Furthermore, we demonstrate that by selecting an appropriate initial vibration state and controlling both the value and sign of the chirp rate, it is possible to achieve preferential cleavage of Cl+CH&lt;sub&gt;2&lt;/sub&gt;Br bonds. This study provides new insights into understanding of ultrafast coherent control of photodissociation reactions in polyatomic molecules.

Advances in Atomic Time Scale Imaging with a Fine Intrinsic Spatial Resolution

Atomic time scale imaging, opening a new era for studying dynamics in microcosmos, is presently attracting immense research interest on the global level due to its powerful ability. On the atom level, physics, chemistry, and biology are identical for researching atom motion and atomic state change. The light possesses twoness, the information carrier and the research resource. The most fundamental principle of this imaging is that light records the event-modulated light field by itself, so-called all-optical imaging. This paper can answer what is the essential standard to develop and evaluate atomic time scale imaging, what is the optimal imaging system, and what are the typical techniques to implement this imaging, up to now. At present, the best record in the experiment, made by multistage optical parametric amplification (MOPA), is realizing 50-fs resolved optical imaging with a spatial resolution of ~83 lp/mm at an effective framing rate of 15 × 10 12 fps for recording an ultrafast optical lattice with its rotating speed up to 13.5 × 10 12 rad/s.

A basic introduction to ultrastable optical cavities for laser stabilization

We give a simple introduction to the properties and use of ultrastable optical cavities, which are increasingly common in atomic and molecular physics laboratories for stabilizing the frequency of lasers to linewidths at the kHz level or below. Although the physics of Fabry–Perot interferometers is part of standard optics curricula, the specificities of ultrastable optical cavities, such as their high finesse, fixed length, and the need to operate under vacuum, can make their use appear relatively challenging to newcomers. Our aim in this work is to bridge the gap between generic knowledge about Fabry–Perot resonators and the specialized literature about ultrastable cavities. The intended audience includes students setting up an ultrastable cavity in a research laboratory for the first time and instructors designing advanced laboratory courses on optics and laser stabilization techniques.

Experimental and theoretical research progress of &lt;sup&gt;2&lt;/sup&gt;P&lt;sub&gt;1/2 &lt;/sub&gt; – &lt;sup&gt;2&lt;/sup&gt;P&lt;sub&gt;3/2&lt;/sub&gt; transitions of highly charged boron-like ions

The precise measurement of the fine structure and radiative transition properties of highly charged ions (HCI) is essential for testing fundamental physical models, including strong-field quantum electrodynamics (QED) effects, electron correlation effects, relativistic effects, and nuclear effects. These measurements also provide critical atomic physics parameters for astrophysics and fusion plasma physics. Compared with the extensively studied hydrogen-like and lithium-like ion systems, boron-like ions exhibit significant contributions in terms of relativistic and QED effects in their fine structure forbidden transitions. High-precision experimental measurements and theoretical calculations of these systems provide important avenues for further testing fundamental physical models in multi-electron systems. Additionally, boron-like ions are considered promising candidates for HCI optical clocks. This paper presents the latest advancements in experimental and theoretical research on the ground state &lt;sup&gt;2&lt;/sup&gt;P&lt;sub&gt;3/2&lt;/sub&gt;—&lt;sup&gt;2&lt;/sup&gt;P&lt;sub&gt;1/2&lt;/sub&gt; transition in boron-like ions, and summarizes the current understanding of their fine and hyperfine structures. It also discusses a proposed experimental setup for measuring the hyperfine splitting of boron-like ions by using an electron beam ion trap combined with high-resolution spectroscopy. This proposal aims to provide a reference for future experimental research on the hyperfine splitting of boron-like ions, to test the QED effects with higher precision, extract the radius of nuclear magnetization distribution, and validate relevant nuclear structure models.

From “strong-field atomic physics” to “strong-field nuclear physics”

&lt;sec&gt;In the mid-1980s, chirped pulse amplification (Nobel Prize in Physics 2018) broke through previous limits to laser intensity, allowing intensities to exceed the atomic unit threshold (1 atomic unit of laser intensity corresponds to a power density of 3.5×10&lt;sup&gt;16&lt;/sup&gt; W/cm&lt;sup&gt;2&lt;/sup&gt;). These strong laser fields can cause high-order nonlinear responses in atoms and molecules, resulting in a series of novel phenomena, among which high-order harmonic generation and attosecond pulse generation (Nobel Prize in Physics 2023) are particularly important. With the development of high-power laser technology, laser intensity has now reached the order of 10&lt;sup&gt;23&lt;/sup&gt; W/cm&lt;sup&gt;2&lt;/sup&gt; and is constantly increasing. Now, a fundamental question has been raised: can such a powerful laser field induce similar high-order nonlinear responses in atomic nuclei, potentially transitioning “strong-field atomic physics” into “strong-field nuclear physics”?&lt;/sec&gt;&lt;sec&gt;To explore this, we investigate a dimensionless parameter that estimates the strength of light-matter interaction: &lt;inline-formula&gt;&lt;tex-math id="M1"&gt;\begin{document}$ \eta = D{E_0}/{{\Delta }}E $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;, where &lt;i&gt;D&lt;/i&gt; is the transition moment (between two representative levels of the system), &lt;i&gt;E&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt; is the laser field amplitude, &lt;i&gt;DE&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt; quantifies the laser-matter interaction energy, and Δ&lt;i&gt;E&lt;/i&gt; is the transition energy. If &lt;inline-formula&gt;&lt;tex-math id="M2"&gt;\begin{document}$ \eta \ll 1 $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;, the interaction is within the linear, perturbative regime. However, when &lt;inline-formula&gt;&lt;tex-math id="M3"&gt;\begin{document}$ \eta \sim 1 $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;, highly nonlinear responses are anticipated. For laser-atom interactions, &lt;i&gt;D&lt;/i&gt; ~ 1 a.u. and Δ&lt;i&gt;E&lt;/i&gt; = 1 a.u., so if &lt;i&gt;E&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt; ~ 1 a.u., then &lt;inline-formula&gt;&lt;tex-math id="M4"&gt;\begin{document}$ \eta \sim 1 $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; and highly nonlinear responses are initiated, leading to the above-mentioned strong-field phenomena.&lt;/sec&gt;&lt;sec&gt;In the case of light-nucleus interaction, it is typical that &lt;inline-formula&gt;&lt;tex-math id="M5"&gt;\begin{document}$ \eta \ll 1 $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt;. When considering nuclei instead of atoms, &lt;i&gt;D&lt;/i&gt; becomes several (~5 to 7) orders of magnitude smaller, while Δ&lt;i&gt;E&lt;/i&gt; becomes several (~5) orders of magnitude larger. Consequently, the laser field amplitude &lt;i&gt;E&lt;/i&gt;&lt;sub&gt;0&lt;/sub&gt; will need to be 10 orders of magnitude higher, or the laser intensity needs to be 20 orders of magnitude higher (~ 10&lt;sup&gt;36&lt;/sup&gt; W/cm&lt;sup&gt;2&lt;/sup&gt;), which is beyond existing technological limit and even exceeds the Schwinger limit, where vacuum breakdown occurs.&lt;/sec&gt;&lt;sec&gt;However, there exist special nuclei with exceptional properties. For instance, the &lt;sup&gt;229&lt;/sup&gt;Th nucleus has a uniquely low-lying excited state with an energy value of only 8.4 eV, or 0.3 a.u. This unusually low transition energy significantly increases &lt;i&gt;η&lt;/i&gt;. This transition has also been proposed for building nuclear clocks, which have potential advantages over existing atomic clocks.&lt;/sec&gt;&lt;sec&gt;Another key factor is nuclear hyperfine mixing (NHM). An electron, particularly the one in an inner orbital, can generate a strong electromagnetic field at the position of the nucleus, leading to the mixing of nuclear eigenstates. For &lt;sup&gt;229&lt;/sup&gt;Th, this NHM effect is especially pronounced: the lifetime of the 8.4-eV nuclear isomeric state in a bare &lt;sup&gt;229&lt;/sup&gt;Th nucleus (&lt;sup&gt;229&lt;/sup&gt;Th&lt;sup&gt;90+&lt;/sup&gt;) is on the order of 10&lt;sup&gt;3&lt;/sup&gt; s, while in the hydrogenlike ionic state (&lt;sup&gt;229&lt;/sup&gt;Th&lt;sup&gt;89+&lt;/sup&gt;) it decreases by five orders of magnitude to 10&lt;sup&gt;–2&lt;/sup&gt; s. This 1s electron greatly affects the properties of the &lt;sup&gt;229&lt;/sup&gt;Th nucleus, effectively changing the nuclear transition moment from &lt;i&gt;D&lt;/i&gt; for the bare nucleus to &lt;inline-formula&gt;&lt;tex-math id="M6"&gt;\begin{document}$ D' = D + b{\mu _{\text{e}}} $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; for the hydrogenlike ion, where &lt;i&gt;D&lt;/i&gt; ~ 10&lt;sup&gt;–7&lt;/sup&gt; a.u., &lt;inline-formula&gt;&lt;tex-math id="M7"&gt;\begin{document}$ b \approx 0.03 $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; is the mixing coefficient, &lt;inline-formula&gt;&lt;tex-math id="M8"&gt;\begin{document}$ {\mu _{\text{e}}} $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; is the magnetic moment of the electron, and &lt;inline-formula&gt;&lt;tex-math id="M9"&gt;\begin{document}$ D'\approx b\mu_{\text{e}}\sim10^{-4}\ \text{a}\text{.u}. $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; That is to say, the existence of the 1s electron increases the light-nucleus coupling matrix element by approximately three orders of magnitude, leading to the five-orders-of-magnitude reduction in the isomeric lifetime.&lt;/sec&gt;&lt;sec&gt;With the minimized transition energy Δ&lt;i&gt;E&lt;/i&gt; and the NHM-enhanced transition moment &lt;i&gt;D'&lt;/i&gt;, it is found that &lt;inline-formula&gt;&lt;tex-math id="M10"&gt;\begin{document}$ \eta \sim 1 $\end{document}&lt;/tex-math&gt;&lt;/inline-formula&gt; for currently achievable laser intensities. Highly nonlinear responses are expected in the &lt;sup&gt;229&lt;/sup&gt;Th nucleus. This is confirmed by our numerical results. Highly efficient nuclear isomeric excitation can be achieved: an excitation probability of over 10% is achieved per nucleus per femtosecond laser pulse at a laser intensity of 10&lt;sup&gt;21&lt;/sup&gt; W/cm&lt;sup&gt;2&lt;/sup&gt;. Correspondingly, the intense laser-driven &lt;sup&gt;229&lt;/sup&gt;Th&lt;sup&gt;89+&lt;/sup&gt; system emits secondary light in the form of high harmonics, which share similarities with those from laser-driven atoms but also have different features.&lt;/sec&gt;&lt;sec&gt;In conclusion, it appears feasible to extend “strong-field atomic physics” to “strong-field nuclear physics”, at least in the case of &lt;sup&gt;229&lt;/sup&gt;Th. “Strong-field nuclear physics” is emerging as a new frontier in light-matter interaction and nuclear physics, providing opportunities for precisely exciting and controlling atomic nuclei with intense lasers and new avenues for coherent light emission based on nuclear transitions.&lt;/sec&gt;

Fifty Years of Atomic Physics

Fifty Years of Atomic Physics

Exploring Atomic Physics Teaching Based on Atomic Models

Exploring Atomic Physics Teaching Based on Atomic Models

原子物理教学中科学精神的融入

原子物理教学中科学精神的融入

Radiation knowledge and awareness: Evaluation from the perspective of high school students

This study aimed to determine the knowledge and awareness levels of students studying in the 12th grade of secondary education about the concept of radiation. In line with the purpose of the study, the phenomenological approach, one of the qualitative research methods, was used. The study participants comprised 28 students who studied the subject of ‘Introduction to Atomic Physics and Radioactivity’ in the 12th-grade curriculum of secondary physics courses in secondary education institutions affiliated with the Ministry of National Education in the 2023-2024 academic year. The study used seven open-ended questions developed by the researchers as data collection tools. The data obtained from the interviews were subjected to content analysis. As a result of the research, it was determined that the students defined radiation as a harmful ray at most. At the same time, it was determined that the students primarily associated radiation with electronic devices and thought radiation could be transmitted from human to human. Considering the data obtained, it was concluded that the students had incomplete and erroneous information about radiation; therefore, their awareness of radiation was not high.

Free electron laser prepared high-intensity metastable helium and helium-like ions

In the precision spectroscopy of few-electron atoms, the generation of high-intensity metastable helium atoms and helium-like ions is crucial for implementing experimental studies as well as a critical factor for improving the signal-to-noise ratio of experimental measurements. With the rapid development of free-electron laser (FEL) and technology, FEL wavelengths extend from hard X-rays to soft X-rays and even vacuum ultraviolet bands. Meanwhile, laser pulses with ultra-fast, ultra-intense and high repetition frequencies are realized, thus making it possible for FEL to prepare single-quantum state atoms/ions with high efficiency. In this work, we propose an experimental method for obtaining high-intensity single-quantum state helium atoms and helium-like ions by using FEL. The preparation efficiency can be calculated by solving the master equation of light-atom interaction. Considering the experimental parameters involved in this work, we predict that the efficiencies of preparing metastable 2&lt;sup&gt;3&lt;/sup&gt;S He, Li&lt;sup&gt;+&lt;/sup&gt; and Be&lt;sup&gt;2+&lt;/sup&gt; are about 3%, 6% and 2%, respectively. Compared with the common preparation methods such as gas discharge and electron bombardment, a state-of-the-art laser excitation method can not only increase the preparation efficiency, but also reduce the effects of high-energy stray particles such as electrons, ions, and photons generated during discharge. Furthermore, combined with the laser preparation technique, the sophisticated ion confinement technique, which can ensure a long interaction time between the ions and laser, increases the efficiency of metastable Li&lt;sup&gt;+&lt;/sup&gt; and Be&lt;sup&gt;2+&lt;/sup&gt; by several orders of magnitude. Therefore, the preparation of high-intensity metastable helium and helium-like ions can improve the measurement accuracy of precision spectroscopy of atoms and ions. A new experimental method, based on FEL, to study the fine structure energy levels 2&lt;sup&gt;3&lt;/sup&gt;P of helium, has the potential to obtain the results with an accuracy exceeding the sub-kHz level. Thus, the high-precision fine structure constants can be determined with the development of high-order quantum electrodynamics theory. In order to measure energy levels with higher accuracy, a new detection technique, which can reduce or even avoid more systematic effects, must be developed. For example, the quantum interference effect, which has been proposed in recent years, seriously affects the accuracy of fine-structure energy levels. If the interference phenomenon of spontaneous radiation between different excited states can be avoided in the detection process, the measurement accuracy will not be affected by this quantum interference effect. High-intensity metastable atoms or ions in chemical reaction dynamics studies also have better chances to investigate reaction mechanisms. In summary, the FEL preparation of high-intensity metastable helium atoms and helium-like ions proposed in this work will lay an important foundation for developing cold atom physics and chemical reaction dynamics.