Journal of Physics B: Atomic, Molecular and Optical Physics最新文献

{"title":"Sub-Doppler laser cooling and magnetic trapping of natural-abundance fermionic potassium","authors":"Mateusz Bocheński, Mariusz Semczuk","doi":"10.1088/1361-6455/ad2181","DOIUrl":"https://doi.org/10.1088/1361-6455/ad2181","url":null,"abstract":"We demonstrate the largest number of <sup>40</sup>K atoms that has ever been cooled to deeply sub-Doppler temperatures in a single-chamber apparatus without using an enriched source of potassium. With gray molasses cooling on the <italic toggle=\"yes\">D</italic>\u0000<sub>1</sub>-line following a standard <italic toggle=\"yes\">D</italic>\u0000<sub>2</sub>-line magneto-optical trap, we obtain <inline-formula>\u0000<tex-math><?CDATA $3times10^5$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mn>3</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mn>5</mml:mn></mml:msup></mml:math>\u0000<inline-graphic xlink:href=\"bad2181ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> atoms at 10(2) <italic toggle=\"yes\">µ</italic>K. We reach densities high enough to measure the temperature via absorption imaging using the time-of-flight method. We magnetically trap a mixture of <inline-formula>\u0000<tex-math><?CDATA $m_F = -3/2,-5/2$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mi>m</mml:mi><mml:mi>F</mml:mi></mml:msub><mml:mo>=</mml:mo><mml:mo>−</mml:mo><mml:mn>3</mml:mn><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mn>2</mml:mn><mml:mo>,</mml:mo><mml:mo>−</mml:mo><mml:mn>5</mml:mn><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:math>\u0000<inline-graphic xlink:href=\"bad2181ieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> and <inline-formula>\u0000<tex-math><?CDATA $-7/2$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mo>−</mml:mo><mml:mn>7</mml:mn><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:math>\u0000<inline-graphic xlink:href=\"bad2181ieqn3.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> Zeeman states of the <inline-formula>\u0000<tex-math><?CDATA $F = 7/2$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mi>F</mml:mi><mml:mo>=</mml:mo><mml:mn>7</mml:mn><mml:mrow><mml:mo>/</mml:mo></mml:mrow><mml:mn>2</mml:mn></mml:math>\u0000<inline-graphic xlink:href=\"bad2181ieqn4.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> hyperfine ground state confining <inline-formula>\u0000<tex-math><?CDATA $5times10^4$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mn>5</mml:mn><mml:mo>×</mml:mo><mml:msup><mml:mn>10</mml:mn><mml:mn>4</mml:mn></mml:msup></mml:math>\u0000<inline-graphic xlink:href=\"bad2181ieqn5.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> atoms with a lifetime of 0.6 s or <inline-formula>\u0000<tex-math><?CDATA ${sim}10^3$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mrow><mml:mo>∼</mml:mo></mml:mrow><mml:msup><mml:mn>10</mml:mn><mml:mn>3</mml:mn></mml:msup></mml:math>\u0000<inline-graphic xlink:href=\"bad2181ieqn6.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> atoms with a lifetime of 2.8 s—depending on whether the temperature of the potassium dispensers was chosen to maximize the atom number or the lifetime. The background pressure-limited lifetime of 0.6 s is a reasonable starting point for proof-of-principle experiments with atoms and/or molecules in optical tweezers as well as for sympathetic cool","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"86 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-02-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139769766","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A data-driven machine learning approach for electron-molecule ionization cross sections","authors":"A L Harris, J Nepomuceno","doi":"10.1088/1361-6455/ad2185","DOIUrl":"https://doi.org/10.1088/1361-6455/ad2185","url":null,"abstract":"Despite their importance in a wide variety of applications, the estimation of ionization cross sections for large molecules continues to present challenges for both experiment and theory. Machine learning (ML) algorithms have been shown to be an effective mechanism for estimating cross section data for atomic targets and a select number of molecular targets. We present an efficient ML model for predicting ionization cross sections for a broad array of molecular targets. Our model is a 3-layer neural network that is trained using published experimental datasets. There is minimal input to the network, making it widely applicable. We show that with training on as few as 10 molecular datasets, the network is able to predict the experimental cross sections of additional molecules with an accuracy similar to experimental uncertainties in existing data. As the number of training molecular datasets increased, the network’s predictions became more accurate and, in the worst case, were within 30% of accepted experimental values. In many cases, predictions were within 10% of accepted values. Using a network trained on datasets for 25 different molecules, we present predictions for an additional 27 molecules, including alkanes, alkenes, molecules with ring structures, and DNA nucleotide bases.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"10 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-02-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139769765","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electron scattering and transport in simple liquid mixtures","authors":"G J Boyle, N A Garland, R P McEachran, K A Mirihana, R E Robson, J P Sullivan, R D White","doi":"10.1088/1361-6455/ad1d35","DOIUrl":"https://doi.org/10.1088/1361-6455/ad1d35","url":null,"abstract":"The theory for electron transport in simple liquids developed by Cohen and Lekner (1967 <italic toggle=\"yes\">Phys. Rev.</italic>\u0000<bold>158</bold> 305), is extended to simple liquid mixtures. The focus is on developing benchmark models for binary mixtures of hard-spheres, using the Percus-Yevick model (Lebowitz 1964 <italic toggle=\"yes\">Phys. Rev.</italic> A <bold>133</bold> 895, Hiroike 1969 <italic toggle=\"yes\">J. Phys. Soc. Japan</italic>\u0000<bold>27</bold> 1415) to represent the density structure effects. A multi-term solution of Boltzmann’s equation is employed to investigate the effect of the binary mixture structure on hard-sphere electron scattering cross-sections and transport properties, including the drift velocity, mean energy, longitudinal and transverse diffusion coefficients. Benchmark calculations are established for electrons driven out of equilibrium by a range of reduced electric field strengths (<inline-formula>\u0000<tex-math><?CDATA $0.1{-}100$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mn>0.1</mml:mn><mml:mrow><mml:mo>−</mml:mo></mml:mrow><mml:mn>100</mml:mn></mml:math>\u0000<inline-graphic xlink:href=\"bad1d35ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> Td).","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"6 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139770649","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Research on the influence of intra-cavity dispersion on pulse characteristics of a quartic soliton fiber laser","authors":"Honglin Wen, Lie Liu, Ying Han, Xiaotong Gao, Haijun Gu, Yadong Sun, Bo Gao","doi":"10.1088/1361-6455/ad1d34","DOIUrl":"https://doi.org/10.1088/1361-6455/ad1d34","url":null,"abstract":"\u0000 We numerically investigate the influence of higher-order dispersion on the dynamics of quartic solitons in a passively mode-locked fiber laser. The simulation results show that the output pulse characteristics of the quartic soliton fiber laser are not only affected by the intra-cavity net dispersion but also related to the position of the single-mode fiber (SMF). For different intra-cavity net higher-order dispersion values, the quartic soliton undergoes multiple alternations between the stable single soliton state and pulsating state in the fiber laser, and the number and intensity of Kelly sidebands in the output pulse spectrum are significantly different. For different positions of the SMF, the dynamics of the quartic soliton are also different. In addition, we also observe two types of novel pulsation-creeping behavior and time shift. These findings provide new insights into the output characteristics of quartic solitons in fiber lasers.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"1 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139439399","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Electron and ion spectroscopy of camphor doped helium nanodroplets in the extreme UV and soft x-ray regime","authors":"S. Sen, S. Mandal, Subhendu De, Arnab Sen, Ram Gopal, L. Ben Ltaief, Stefano Turchini, D. Catone, Nicola Zema, M. Coreno, Robert Richter, M. Mudrich, Vandana Sharma, Sivarama Krishnan","doi":"10.1088/1361-6455/ad1d37","DOIUrl":"https://doi.org/10.1088/1361-6455/ad1d37","url":null,"abstract":"\u0000 We investigate the ionisation and fragmentation dynamics of free camphor molecules and camphor-doped helium nanodroplets by extreme ultraviolet (EUV) and soft x-ray photons using velocity map imaging combined with photoelectron–photoion coincidence (VMI-PEPICO) spectroscopy. We notably find that the Penning ionisation of camphor in He nanodroplets at hν= 21.43 eV is soft with nearly identical Penning ionised electron spectra correlated to different molecular fragments. Further, fragmentation following ionisation at all photon energies exhibit a droplet-specific mass peak equivalent to the missing mass of CO, suggesting suppression of further fragmentation inside the droplet. This work reveals unusual features of photoionisation of organic molecules doped in He nanodroplet motivating further experimental and theoretical explorations.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"1 8","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139440095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Inner-shell photoelectron spectroscopy unveils the interplay between hydrogen bonds and π − π stacking in clusters of biomolecules in the gas phase: hypoxanthine clusters as a case study","authors":"Darío Barreiro-Lage, Giuseppe Mattioli, C. Nicolafrancesco, Patrick Rousseau, Aleksandar Milosavljevic, S. Dı́az-Tendero","doi":"10.1088/1361-6455/ad1d36","DOIUrl":"https://doi.org/10.1088/1361-6455/ad1d36","url":null,"abstract":"\u0000 We present a joint theoretical-experimental study on the inner-shell photoionization of hypoxanthine clusters in the gas phase. Simulations were performed using a computational strategy that combines molecular dynamics to explore the conformers of the clusters, density functional theory for geometry optimization and inner shell photoionization calculations. Two main intermolecular interactions are observed: hydrogen-bonds (HB) and π-π stacking. When increasing the cluster size, a combination of both kinds of interaction occurs. We show that such intermolecular interactions play a role in the chemical shift observed in X-ray photoemission spectroscopy experiments. In particular, we highlight the interplay between charge depletion and charge accumulation in regions where HBs stabilize the clusters.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"16 11","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-01-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139439112","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Outcomes of a novel single case study incorporating Rapid Syllable Transition treatment, AAC and blended intervention in children with cerebral palsy: a pilot study.","authors":"Marjut Johanna Korkalainen, Patricia McCabe, Andy Smidt, Catherine Morgan","doi":"10.1080/17483107.2022.2071488","DOIUrl":"10.1080/17483107.2022.2071488","url":null,"abstract":"<p><strong>Purpose: </strong>Motor speech and augmentative and alternative communication (AAC) interventions are commonly used with children with cerebral palsy (CP) but there is limited literature comparing the effectiveness of these interventions. The purpose of this study was to investigate the effectiveness of intensive AAC, Rapid Syllable Transition Treatment (ReST), and blended intervention, a combination of motor-speech and AAC, on speech accuracy and sentence length and complexity.</p><p><strong>Methods: </strong>A single case experimental design across participants with repeated measurements across phases (ABACADA design) was used. Four participants aged 8-14 years with CP who used a speech-generating device (SGD) received three 6-week intervention blocks that included ReST, AAC, and blended intervention. Measures were taken during intervention and baseline phases and at maintenance two and four weeks after the last intervention phase. Participants were randomized to starting with either ReST or AAC with the blended intervention delivered last.</p><p><strong>Results: </strong>All participants improved their speech accuracy and sentence length and complexity in speech and with their SGD in all three interventions. The data demonstrated overall immediacy of the effect with all interventions and retention of gains across the whole sequence of phases. The order of AAC or ReST interventions or the severity of CP did not impact the intervention gains.</p><p><strong>Conclusion: </strong>This study suggests that intensive AAC, a multi-modal approach, and ReST improve speech accuracy and sentence length and complexity in children with moderate CP, but all require further investigation.Implications for rehabilitationIn this paper intensive AAC intervention with a speech generating device (SGD), ReST treatment and multimodal blended intervention were effective in improving speech accuracy and sentence length and complexity in both verbal speech and on communication with the SGD.ReST treatment has not been used with children with CP before. This study established a proof of concept for its effectiveness in children with CP. Further research is warranted.</p>","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"36 1","pages":"167-176"},"PeriodicalIF":2.2,"publicationDate":"2024-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82513592","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dissociative electron attachment studies of gas-phase acetic acid using a velocity map imaging technique","authors":"Dipayan Chakraborty, Giorgi Kharchilava, Ian Carmichael, S. Ptasińska","doi":"10.1088/1361-6455/ad1745","DOIUrl":"https://doi.org/10.1088/1361-6455/ad1745","url":null,"abstract":"\u0000 Advancing instrumentation to explore dissociative electron attachment studies allows previously unattainable information to be acquired. Using a newly-constructed velocity map imaging spectrometer, we revisited a study on dissociative electron attachment to gas-phase acetic acid. We discuss possible fragmentation channels and compared the corresponding ion yields with previous high-electron energy resolution results. We focus on the channels occurring at higher energies, particularly near 10 eV, and calculate their thermodynamic thresholds. Moreover, we expand previous studies and perform velocity-slice imaging near the 10 eV resonance to obtain the kinetic energy distribution of the fragment ions.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":" 71","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138961364","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Resonant x-ray difference frequency generation","authors":"Carles Serrat","doi":"10.1088/1361-6455/ad0f39","DOIUrl":"https://doi.org/10.1088/1361-6455/ad0f39","url":null,"abstract":"Resonantly enhanced x-ray difference-frequency generation (re-XDFG) is a second-order nonlinear effect that involves illuminating a molecule with two-color x-ray pulses with photon energies Ω₁ and Ω₂. The energy difference <inline-formula>\u0000<tex-math><?CDATA $Omega_1-Omega_2$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:msub><mml:mi mathvariant=\"normal\">Ω</mml:mi><mml:mn>1</mml:mn></mml:msub><mml:mo>−</mml:mo><mml:msub><mml:mi mathvariant=\"normal\">Ω</mml:mi><mml:mn>2</mml:mn></mml:msub></mml:math>\u0000<inline-graphic xlink:href=\"bad0f39ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> is tuned to match an x-ray absorption edge of an atom in the molecule. We have numerically studied the re-XDFG effect considering different individual molecules in the gas phase using density functional theory calculations and have verified the non-centrosymmetric character of the target transitions. Two-level molecular systems with permanent dipoles are evaluated for the description of re-XDFG taking into account different two-color input pulse geometries. This innovative nonlinear x-ray methodology offers a means to measure the K-edge NEXAFS spectrum of light elements, such as carbon, nitrogen, or oxygen, in dense media using non-resonant x-rays. It can also be used to investigate chemical material dynamics that are inaccessible by linear spectroscopy. These findings enable the combination of atomic-scale structure with chemical specificity and the selective and local access to x-ray excitations using hard x-ray pulses.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"7 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139057283","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nonorthogonal coding in spectrally-entangled photons","authors":"N-Y Tsai, H H Jen","doi":"10.1088/1361-6455/ad12d5","DOIUrl":"https://doi.org/10.1088/1361-6455/ad12d5","url":null,"abstract":"Controlling and engineering continuous spectral modes of entangled photons represents one of the promising approaches toward secure quantum communications. By using the telecom bandwidth generated from a cascade-emitted biphoton in atomic ensembles, a fiber-based long-distance quantum communication can be feasible owing to its low transmission loss. With multiplexed photon pairs, we propose to implement a nonorthogonal coding scheme in their spectral modes and present an architecture of multiple channels enabling a high-capacity transfer of codewords. Using the measures of the second-order correlations and associated visibility and contrast, we further quantify the performance of the proposed nonorthogonal coding scheme. Our results demonstrate the capability to encode and decode quantum information beyond the orthogonal coding scheme, and in particular, the multi-channel setup manifests a resilience and an advantage in a design with multiple channel errors. The proposed scheme here can be applicable to a large-scale and multiuser quantum communication and pave the way toward an efficient and functional quantum information processing.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"12 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2023-12-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138682174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}