Pub Date : 2024-08-06DOI: 10.1088/1361-6455/ad5e24
Jack D Briscoe, Danielle Pizzey, Steven A Wrathmall and Ifan G Hughes
The Kramers–Kronig relations are a pivotal foundation of linear optics and atomic physics, embedding a physical connection between the real and imaginary components of any causal response function. A mathematically equivalent, but simpler, approach instead utilises the Hilbert transform. In a previous study, the Hilbert transform was applied to absorption spectra in order to infer the sole refractive index of an atomic medium in the absence of an external magnetic field. The presence of a magnetic field causes the medium to become birefringent and dichroic, and therefore it is instead characterised by two refractive indices. In this study, we apply the same Hilbert transform technique to independently measure both refractive indices of a birefringent atomic medium, leading to an indirect measurement of atomic magneto-optical rotation. Key to this measurement is the insight that inputting specific light polarisations into an atomic medium induces absorption associated with only one of the refractive indices. We show this is true in two configurations, commonly referred to in literature as the Faraday and Voigt geometries, which differ by the magnetic field orientation with respect to the light wavevector. For both cases, we measure the two refractive indices independently for a Rb thermal vapour in a magnetic field, finding excellent agreement with theory. This study further emphasises the application of the Hilbert transform to the field of quantum and atomic optics in the linear regime.
{"title":"Indirect measurement of atomic magneto-optical rotation via Hilbert transform","authors":"Jack D Briscoe, Danielle Pizzey, Steven A Wrathmall and Ifan G Hughes","doi":"10.1088/1361-6455/ad5e24","DOIUrl":"https://doi.org/10.1088/1361-6455/ad5e24","url":null,"abstract":"The Kramers–Kronig relations are a pivotal foundation of linear optics and atomic physics, embedding a physical connection between the real and imaginary components of any causal response function. A mathematically equivalent, but simpler, approach instead utilises the Hilbert transform. In a previous study, the Hilbert transform was applied to absorption spectra in order to infer the sole refractive index of an atomic medium in the absence of an external magnetic field. The presence of a magnetic field causes the medium to become birefringent and dichroic, and therefore it is instead characterised by two refractive indices. In this study, we apply the same Hilbert transform technique to independently measure both refractive indices of a birefringent atomic medium, leading to an indirect measurement of atomic magneto-optical rotation. Key to this measurement is the insight that inputting specific light polarisations into an atomic medium induces absorption associated with only one of the refractive indices. We show this is true in two configurations, commonly referred to in literature as the Faraday and Voigt geometries, which differ by the magnetic field orientation with respect to the light wavevector. For both cases, we measure the two refractive indices independently for a Rb thermal vapour in a magnetic field, finding excellent agreement with theory. This study further emphasises the application of the Hilbert transform to the field of quantum and atomic optics in the linear regime.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"46 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-08-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141937009","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}
Pub Date : 2024-07-24DOI: 10.1088/1361-6455/ad6385
Peter B Weichman
Radio frequency antennas based on Rydberg atom vapor cells can in principle reach sensitivities beyond those of any conventional wire antenna, especially at lower frequencies where very long wires are needed to accommodate the increasing wavelength. They also have other desirable features such as consisting of nonmetallic, hence lower profile, elements. This paper presents a detailed theoretical investigation of Rydberg antenna sensitivity, elucidating parameter regimes that could cumulatively lead to a sensitivity increase 2–3 orders of magnitude beyond that of currently tested configurations. The key insight is to optimally combine the advantages of two well-studied approaches: (i) three laser ‘2D star configuration’ setups that, when enhanced with increased laser power, to some degree compensate for atom motion-induced Doppler broadening, and (ii) resonant coupling between a pair of near-degenerate Rydberg levels, tuned via a local oscillator to the incident signal of interest. The advantage of the star setup is subtle because it only restores the overall sensitivity to the expected Doppler-limited value, compensating for additional significant off-resonance reductions where differently moving atom sub-populations destructively interfere with each other in the net signal. An additional unique advantage of local oscillator tuning is that it leads to vastly narrower line widths, as low as ∼10 kHz set by the intrinsic Rydberg state lifetimes, rather than the typical ∼10 MHz scale set by the core state lifetimes. Intuitively, with this setup the two Rydberg states may be tuned to act as an independent high-q cavity, a point of view supported by a study of the frequency-dependence of the antenna resonant response. There are a number of practical experimental advances, especially larger ∼1 cm laser beam widths, required to suppress various extrinsic line broadening effects and to fully exploit this ‘Rydberg superheterodyne’ response.
{"title":"Doppler sensitivity and resonant tuning of Rydberg atom-based antennas","authors":"Peter B Weichman","doi":"10.1088/1361-6455/ad6385","DOIUrl":"https://doi.org/10.1088/1361-6455/ad6385","url":null,"abstract":"Radio frequency antennas based on Rydberg atom vapor cells can in principle reach sensitivities beyond those of any conventional wire antenna, especially at lower frequencies where very long wires are needed to accommodate the increasing wavelength. They also have other desirable features such as consisting of nonmetallic, hence lower profile, elements. This paper presents a detailed theoretical investigation of Rydberg antenna sensitivity, elucidating parameter regimes that could cumulatively lead to a sensitivity increase 2–3 orders of magnitude beyond that of currently tested configurations. The key insight is to optimally combine the advantages of two well-studied approaches: (i) three laser ‘2D star configuration’ setups that, when enhanced with increased laser power, to some degree compensate for atom motion-induced Doppler broadening, and (ii) resonant coupling between a pair of near-degenerate Rydberg levels, tuned via a local oscillator to the incident signal of interest. The advantage of the star setup is subtle because it only restores the overall sensitivity to the expected Doppler-limited value, compensating for additional significant off-resonance reductions where differently moving atom sub-populations destructively interfere with each other in the net signal. An additional unique advantage of local oscillator tuning is that it leads to vastly narrower line widths, as low as ∼10 kHz set by the intrinsic Rydberg state lifetimes, rather than the typical ∼10 MHz scale set by the core state lifetimes. Intuitively, with this setup the two Rydberg states may be tuned to act as an independent high-q cavity, a point of view supported by a study of the frequency-dependence of the antenna resonant response. There are a number of practical experimental advances, especially larger ∼1 cm laser beam widths, required to suppress various extrinsic line broadening effects and to fully exploit this ‘Rydberg superheterodyne’ response.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"2 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141782045","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}
Pub Date : 2024-07-17DOI: 10.1088/1361-6455/ad5e20
R Hassaine, F Gauchet, F Iacob, J Zs Mezei, E Roueff, J Tennyson and I F Schneider
Cross sections and rate coefficients for the dissociative recombination (DR) of the NS+ ion induced by collisions with low-energy electrons are reported for temperatures between 10 and 1000 K, relevant to a large range of interstellar cloud temperatures. Uncertainties are discussed for these rates. Comparisons are made with DR rates for the isovalent NO+ molecular ion which are found to be much faster. The present findings lead to a moderate dissociative reaction rate coefficient, smaller by a factor of 2 than the current estimates reported in the different kinetic databases for a temperature of 10 K. We consider that our rate coefficients obtained through multichannel quantum defect theory for NS+ are likely to be better than those displayed in the different kinetic databases.
报告了与低能电子碰撞诱发的 NS+ 离子离解重组（DR）的截面和速率系数，其温度介于 10 和 1000 K 之间，与星际云温度的大范围相关。讨论了这些速率的不确定性。与异价 NO+ 分子离子的 DR 速率进行了比较，发现后者要快得多。我们认为，我们通过多通道量子缺陷理论获得的 NS+ 的速率系数很可能优于不同动力学数据库中显示的速率系数。
{"title":"Dissociative recombination of NS+ in collision with slow electrons","authors":"R Hassaine, F Gauchet, F Iacob, J Zs Mezei, E Roueff, J Tennyson and I F Schneider","doi":"10.1088/1361-6455/ad5e20","DOIUrl":"https://doi.org/10.1088/1361-6455/ad5e20","url":null,"abstract":"Cross sections and rate coefficients for the dissociative recombination (DR) of the NS+ ion induced by collisions with low-energy electrons are reported for temperatures between 10 and 1000 K, relevant to a large range of interstellar cloud temperatures. Uncertainties are discussed for these rates. Comparisons are made with DR rates for the isovalent NO+ molecular ion which are found to be much faster. The present findings lead to a moderate dissociative reaction rate coefficient, smaller by a factor of 2 than the current estimates reported in the different kinetic databases for a temperature of 10 K. We consider that our rate coefficients obtained through multichannel quantum defect theory for NS+ are likely to be better than those displayed in the different kinetic databases.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"181 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141737444","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}
Pub Date : 2024-07-11DOI: 10.1088/1361-6455/ad5e22
Atharva Paranjape, Shyamal Guchhait, Athira B S and Nirmalya Ghosh
Laguerre–Gaussian (LG) beams carrying orbital angular momentum (OAM) have shown promise in deep tissue imaging, medical diagnostics, and optical communication due to their robust propagation properties through scattering media. The insight on the mechanism for stronger survival of OAM carrying beam in tissue-like turbid media is expected to contribute towards a better understanding of light transport in the presence of scattering, as well as guide optimization of the intensity, phase, and polarization structure of light for use in biomedical applications like in tissue imaging. We examine the scattering properties by studying the propagation of polarized vortex beams transmitted through tissue-like turbid scattering media. We demonstrate that the intensity profile has a much more profound effect on depolarization than the phase profile for LG beams. Our results indicate that the observed stronger propagation for the higher-order LG beams is due to a higher anisotropy factor g, as seen by the incident beam. We have performed the degree of polarization measurements for the forward scattered light in the case of both LG beams and perfect vortex beams with varying topological charges. A comparison between the observed depolarization trends for the two classes of OAM-carrying beams suggests that the robust scattering properties of the LG beams originate from the intensity profile while the phase profile does not seem to play a major role in the stronger survival of OAM-carrying beam in turbid media.
携带轨道角动量（OAM）的拉盖尔-高斯（LG）光束因其在散射介质中的强大传播特性，在深部组织成像、医疗诊断和光通信领域大有可为。深入了解携带轨道角动量（OAM）的光束在组织类浑浊介质中更强的生存机制，有望有助于更好地理解散射情况下的光传输，并指导优化光的强度、相位和偏振结构，以用于组织成像等生物医学应用。我们通过研究偏振涡旋光束在组织类浊度散射介质中的传播来检验散射特性。我们证明，对于 LG 光束而言，强度曲线对去极化的影响要比相位曲线大得多。我们的研究结果表明，高阶 LG 光束的强传播是由于入射光束的各向异性因子 g 较高所致。我们对 LG 光束和具有不同拓扑电荷的完美涡旋光束的前向散射光进行了偏振度测量。对两类携带 OAM 的光束所观察到的去极化趋势进行比较后发现，LG 光束的强大散射特性源于其强度曲线，而相位曲线似乎对携带 OAM 的光束在浊介质中更强的生存能力不起主要作用。
{"title":"Exploring the origin of stronger survival of polarized vortex beams through scattering media","authors":"Atharva Paranjape, Shyamal Guchhait, Athira B S and Nirmalya Ghosh","doi":"10.1088/1361-6455/ad5e22","DOIUrl":"https://doi.org/10.1088/1361-6455/ad5e22","url":null,"abstract":"Laguerre–Gaussian (LG) beams carrying orbital angular momentum (OAM) have shown promise in deep tissue imaging, medical diagnostics, and optical communication due to their robust propagation properties through scattering media. The insight on the mechanism for stronger survival of OAM carrying beam in tissue-like turbid media is expected to contribute towards a better understanding of light transport in the presence of scattering, as well as guide optimization of the intensity, phase, and polarization structure of light for use in biomedical applications like in tissue imaging. We examine the scattering properties by studying the propagation of polarized vortex beams transmitted through tissue-like turbid scattering media. We demonstrate that the intensity profile has a much more profound effect on depolarization than the phase profile for LG beams. Our results indicate that the observed stronger propagation for the higher-order LG beams is due to a higher anisotropy factor g, as seen by the incident beam. We have performed the degree of polarization measurements for the forward scattered light in the case of both LG beams and perfect vortex beams with varying topological charges. A comparison between the observed depolarization trends for the two classes of OAM-carrying beams suggests that the robust scattering properties of the LG beams originate from the intensity profile while the phase profile does not seem to play a major role in the stronger survival of OAM-carrying beam in turbid media.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"31 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141608489","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}
Pub Date : 2024-07-11DOI: 10.1088/1361-6455/ad5e25
Annie Ringvall-Moberg, Miranda Nichols, José E Navarro Navarrete, Uldis Bērziņš, Viola C D’mello, Julia Karls, Di Lu, Yazareth Peña Rodríguez, Rachel Poulose, Andrea Morales Rodríguez, Keerthana Ravi, Meera Ramachandran, Vitali Zhaunerchyk, Dag Hanstorp and David Leimbach
Negative ions, which are formed when an electron is attached to a neutral system, are unique quantum systems. The lack of a long-range Coulomb force causes the inter-electronic interactions to become relatively more important. As a consequence, the independent particle model, which adequately describes atomic structure under normal conditions, breaks down. The alkali negative ions, with a closed valence s-shell, are among the simplest anionic systems. Hence, they can favorably be used to benchmark atomic theory. In this work, we have determined the electron affinity of 85Rb by measuring the relative partial photodetachment cross section of the negative ion, leaving the residual atom in the 5p excited state. Resonance ionization spectroscopy allows for state selectivity and the ability to measure the Wigner s-wave threshold onset of the photodetachment process. The electron affinity of 85Rb was determined to be 485.887(6) meV.
{"title":"The electron affinity of rubidium: a state selective measurement","authors":"Annie Ringvall-Moberg, Miranda Nichols, José E Navarro Navarrete, Uldis Bērziņš, Viola C D’mello, Julia Karls, Di Lu, Yazareth Peña Rodríguez, Rachel Poulose, Andrea Morales Rodríguez, Keerthana Ravi, Meera Ramachandran, Vitali Zhaunerchyk, Dag Hanstorp and David Leimbach","doi":"10.1088/1361-6455/ad5e25","DOIUrl":"https://doi.org/10.1088/1361-6455/ad5e25","url":null,"abstract":"Negative ions, which are formed when an electron is attached to a neutral system, are unique quantum systems. The lack of a long-range Coulomb force causes the inter-electronic interactions to become relatively more important. As a consequence, the independent particle model, which adequately describes atomic structure under normal conditions, breaks down. The alkali negative ions, with a closed valence s-shell, are among the simplest anionic systems. Hence, they can favorably be used to benchmark atomic theory. In this work, we have determined the electron affinity of 85Rb by measuring the relative partial photodetachment cross section of the negative ion, leaving the residual atom in the 5p excited state. Resonance ionization spectroscopy allows for state selectivity and the ability to measure the Wigner s-wave threshold onset of the photodetachment process. The electron affinity of 85Rb was determined to be 485.887(6) meV.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"20 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141608491","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}
Pub Date : 2024-07-10DOI: 10.1088/1361-6455/ad5ee5
Jie Yan, Guanpeng Yan, Fengtao Jin, Yongjun Li, Cheng Gao, Jiaolong Zeng and Jianmin Yuan
Theoretical exploration of the population dynamics at fine-structure levels of Ar atoms interacting with ultrafast ultraintense x-ray free electron laser (XFEL) pulses is conducted. A time-dependent rate equation based on a detailed-level accounting approach is applied for tracking population levels, encompassing microscopic atomic processes such as photoexcitation, radiative decay, photoionization and Auger decay. A Monte Carlo algorithm is implemented to solve large-scale rate equations efficiently. The primary investigation centers on generating Ar17+ through resonant absorption by the second-harmonic radiation of the x-ray pulse. The calculated population ratios of Ar17+ to Ar16+ align well with the experimental measurements (LaForge et al 2021 Phys. Rev. Lett.127 213202). In comparison to the transition energy of the strongest line, of Ar16+, there is a distinct ∼25 eV red shift in the peak ratio, which is attributed to the presence of intricate resonant channels in the lower ionization stages. The results demonstrate the sensitivity of the population ratio Ar17+/Ar16+ to the laser pulse parameters such as x-ray pulse duration, bandwidth and the contribution of second-harmonic radiation, indicating their potential as diagnostic tools in future experiments.
对与超快超约束 X 射线自由电子激光（XFEL）脉冲相互作用的氩原子精细结构水平的种群动态进行了理论探索。基于细节级核算方法的随时间变化的速率方程被用于跟踪种群水平，包括光激发、辐射衰变、光离子化和奥格衰变等微观原子过程。采用蒙特卡洛算法有效求解大规模速率方程。主要研究集中在通过 X 射线脉冲二次谐波辐射的共振吸收产生 Ar17+。计算得出的 Ar17+ 与 Ar16+ 的种群比与实验测量结果（LaForge 等人，2021 年，Phys. Rev. Lett.127 213202）非常吻合。与 Ar16+ 的最强线的过渡能量相比，峰值比有明显的 ∼25 eV 红移，这归因于在较低的电离阶段存在错综复杂的共振通道。结果表明了 Ar17+/Ar16+ 的种群比对激光脉冲参数（如 X 射线脉冲持续时间、带宽和二次谐波辐射的贡献）的敏感性，表明它们在未来实验中作为诊断工具的潜力。
{"title":"Evolution of level population in Ar interacting with XFEL pulses: impact of resonant absorptions","authors":"Jie Yan, Guanpeng Yan, Fengtao Jin, Yongjun Li, Cheng Gao, Jiaolong Zeng and Jianmin Yuan","doi":"10.1088/1361-6455/ad5ee5","DOIUrl":"https://doi.org/10.1088/1361-6455/ad5ee5","url":null,"abstract":"Theoretical exploration of the population dynamics at fine-structure levels of Ar atoms interacting with ultrafast ultraintense x-ray free electron laser (XFEL) pulses is conducted. A time-dependent rate equation based on a detailed-level accounting approach is applied for tracking population levels, encompassing microscopic atomic processes such as photoexcitation, radiative decay, photoionization and Auger decay. A Monte Carlo algorithm is implemented to solve large-scale rate equations efficiently. The primary investigation centers on generating Ar17+ through resonant absorption by the second-harmonic radiation of the x-ray pulse. The calculated population ratios of Ar17+ to Ar16+ align well with the experimental measurements (LaForge et al 2021 Phys. Rev. Lett.127 213202). In comparison to the transition energy of the strongest line, of Ar16+, there is a distinct ∼25 eV red shift in the peak ratio, which is attributed to the presence of intricate resonant channels in the lower ionization stages. The results demonstrate the sensitivity of the population ratio Ar17+/Ar16+ to the laser pulse parameters such as x-ray pulse duration, bandwidth and the contribution of second-harmonic radiation, indicating their potential as diagnostic tools in future experiments.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"21 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141585122","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}
Pub Date : 2024-07-09DOI: 10.1088/1361-6455/ad5e21
Anwesha Panda, Sneha Dey, Yogishree Arabinda Panda, Aditya Anurag Dash, Aloke Jana and Nirmalya Ghosh
Spin–orbit interaction of light in a disordered anisotropic medium is known to yield spin split modes in the momentum domain because of the random spatial gradient of the geometric phase of light. Here, we have studied the statistics of such spin-split modes for beams carrying intrinsic orbital angular momentum through the quantification of momentum domain entropy and investigated its dependence on various beam parameters. The influence of the spatial structure of the beam and the phase vortex on the statistics of the spin split modes were separately investigated using input Laguerre–Gaussian and Perfect Vortex beams passing through a disordered anisotropic medium with controlled input disorder parameter, which was realized by modulating the pixels of a liquid crystal-based spatial light modulator. The results of systematic investigations on the impact of beam waist, spot size and topological charge of the vortex beam show that the influence of the spot size on the emergence of the random spin split modes is much more significant as compared to the other beam parameters.
{"title":"Influence of orbital angular momentum of light on random spin-split modes in disordered anisotropic optical media","authors":"Anwesha Panda, Sneha Dey, Yogishree Arabinda Panda, Aditya Anurag Dash, Aloke Jana and Nirmalya Ghosh","doi":"10.1088/1361-6455/ad5e21","DOIUrl":"https://doi.org/10.1088/1361-6455/ad5e21","url":null,"abstract":"Spin–orbit interaction of light in a disordered anisotropic medium is known to yield spin split modes in the momentum domain because of the random spatial gradient of the geometric phase of light. Here, we have studied the statistics of such spin-split modes for beams carrying intrinsic orbital angular momentum through the quantification of momentum domain entropy and investigated its dependence on various beam parameters. The influence of the spatial structure of the beam and the phase vortex on the statistics of the spin split modes were separately investigated using input Laguerre–Gaussian and Perfect Vortex beams passing through a disordered anisotropic medium with controlled input disorder parameter, which was realized by modulating the pixels of a liquid crystal-based spatial light modulator. The results of systematic investigations on the impact of beam waist, spot size and topological charge of the vortex beam show that the influence of the spot size on the emergence of the random spin split modes is much more significant as compared to the other beam parameters.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"7 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141570056","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}
Pub Date : 2024-07-09DOI: 10.1088/1361-6455/ad5c3e
Muskan Arora, Pranav Chokkara, Jasleen Lugani
Photonic integrated optical components, notably straight waveguides, serve as pivotal elements for on-chip generation and manipulation of quantum states of light. In this work, we focus on optimizing waveguides based on lithium niobate on insulator (LNOI) to generate photon pairs at telecom wavelengths using spontaneous parametric down-conversion (SPDC). Specifically, we investigate lateral leakage for all possible SPDC processes involving type 0, type I, and type II phase matching conditions in an X-cut lithium niobate waveguide and provide a recipe to avoid leakage loss for the interacting photons. Furthermore, focusing on type II phase matching, we engineer the waveguide in the single-mode regime such that it also satisfies group index matching for generating spectrally pure single photons with high purity (99.33%). We also address fabrication imperfections of the optimized design and find that the spectral purity of the generated photons is robust to fabrication errors. This work offers guidance for the suitable selection of morphological parameters to obtain lossless, single-mode LNOI waveguides for building linear optical circuits and photon pair generation at telecom wavelengths using desired phase-matching conditions.
光子集成光学元件，特别是直波导，是片上生成和操纵光量子态的关键元件。在这项工作中，我们重点优化基于绝缘体铌酸锂（LNOI）的波导，利用自发参量下转换（SPDC）在电信波长生成光子对。具体来说，我们研究了 X 切面铌酸锂波导中涉及 0 型、I 型和 II 型相位匹配条件的所有可能 SPDC 过程的横向泄漏，并提供了避免相互作用光子泄漏损耗的方法。此外，针对 II 型相位匹配，我们设计了单模波导，使其也能满足群指数匹配，从而产生光谱纯度高（99.33%）的单光子。我们还解决了优化设计的制造缺陷，并发现所产生光子的光谱纯度对制造误差很稳定。这项工作为适当选择形态参数提供了指导，从而获得无损耗、单模 LNOI 波导，用于在电信波长利用所需的相位匹配条件构建线性光路和产生光子对。
{"title":"Avoiding lateral mode leakage in thin film lithium niobate waveguides for the generation of spectrally pure photons at telecom wavelengths","authors":"Muskan Arora, Pranav Chokkara, Jasleen Lugani","doi":"10.1088/1361-6455/ad5c3e","DOIUrl":"https://doi.org/10.1088/1361-6455/ad5c3e","url":null,"abstract":"Photonic integrated optical components, notably straight waveguides, serve as pivotal elements for on-chip generation and manipulation of quantum states of light. In this work, we focus on optimizing waveguides based on lithium niobate on insulator (LNOI) to generate photon pairs at telecom wavelengths using spontaneous parametric down-conversion (SPDC). Specifically, we investigate lateral leakage for all possible SPDC processes involving type 0, type I, and type II phase matching conditions in an X-cut lithium niobate waveguide and provide a recipe to avoid leakage loss for the interacting photons. Furthermore, focusing on type II phase matching, we engineer the waveguide in the single-mode regime such that it also satisfies group index matching for generating spectrally pure single photons with high purity (99.33%). We also address fabrication imperfections of the optimized design and find that the spectral purity of the generated photons is robust to fabrication errors. This work offers guidance for the suitable selection of morphological parameters to obtain lossless, single-mode LNOI waveguides for building linear optical circuits and photon pair generation at telecom wavelengths using desired phase-matching conditions.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"163 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141570057","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}
Pub Date : 2024-07-03DOI: 10.1088/1361-6455/ad31ae
Kensei Kitajima, Takuya Majima and Hidetsugu Tsuchida
Fast heavy-ion collisions with molecules that constitute a liquid are fundamental to the field of radiation chemistry and its application to biology. However, although collision-induced physical and chemical processes in liquids have been extensively studied, the initial stages of such processes remain not fully understood because of their complex behaviors. Accordingly, our group has studied the initial reactions occurring in the vicinity of fast-ion trajectories in liquids by mass spectrometric analysis of the secondary ions ejected from microdroplet surfaces upon fast heavy-ion impacts. In this topical review, we present our recent experimental advances in secondary-ion mass spectrometry using microdroplets of water, alcohols, and amino acid solutions. Our findings demonstrate the complex physicochemical behaviors of positive and negative product ions and highlight the role of secondary electrons in the mechanisms of biomolecular damage triggered by fast heavy ions.
{"title":"Mass spectrometric study of fast heavy-ion induced products on microdroplet surfaces","authors":"Kensei Kitajima, Takuya Majima and Hidetsugu Tsuchida","doi":"10.1088/1361-6455/ad31ae","DOIUrl":"https://doi.org/10.1088/1361-6455/ad31ae","url":null,"abstract":"Fast heavy-ion collisions with molecules that constitute a liquid are fundamental to the field of radiation chemistry and its application to biology. However, although collision-induced physical and chemical processes in liquids have been extensively studied, the initial stages of such processes remain not fully understood because of their complex behaviors. Accordingly, our group has studied the initial reactions occurring in the vicinity of fast-ion trajectories in liquids by mass spectrometric analysis of the secondary ions ejected from microdroplet surfaces upon fast heavy-ion impacts. In this topical review, we present our recent experimental advances in secondary-ion mass spectrometry using microdroplets of water, alcohols, and amino acid solutions. Our findings demonstrate the complex physicochemical behaviors of positive and negative product ions and highlight the role of secondary electrons in the mechanisms of biomolecular damage triggered by fast heavy ions.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"34 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551949","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}
Pub Date : 2024-06-26DOI: 10.1088/1361-6455/ad5992
Michael Devereux
For nearly one hundred years most quantum-mechanics texts have depicted a continuous, spin-direction superposition of the wavefunction of the silver atom traversing a Stern–Gerlach (S–G) magnet. But there are sound scientific arguments which deny that understanding. Schrodinger’s equation for that continuous wavefunction development cannot describe the transfer of energy from the magnetic field to that atom. Modern micro-fabrication techniques now make it possible to implement a simple, accessible experiment testing whether a spin superposition does continue in the magnet. Because the S–G experiment is the prototype for quantum measurement, that observation is crucial to implementing a realistic quantum theory of measurement.
{"title":"A simple, practical experiment to investigate atomic wavefunction reduction within a Stern–Gerlach magnet","authors":"Michael Devereux","doi":"10.1088/1361-6455/ad5992","DOIUrl":"https://doi.org/10.1088/1361-6455/ad5992","url":null,"abstract":"For nearly one hundred years most quantum-mechanics texts have depicted a continuous, spin-direction superposition of the wavefunction of the silver atom traversing a Stern–Gerlach (S–G) magnet. But there are sound scientific arguments which deny that understanding. Schrodinger’s equation for that continuous wavefunction development cannot describe the transfer of energy from the magnetic field to that atom. Modern micro-fabrication techniques now make it possible to implement a simple, accessible experiment testing whether a spin superposition does continue in the magnet. Because the S–G experiment is the prototype for quantum measurement, that observation is crucial to implementing a realistic quantum theory of measurement.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"161 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-06-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141505623","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}
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