arXiv: Atomic Physics最新文献

{"title":"Multicharged-ion–water-molecule collisions in a classical-trajectory time-dependent mean-field theory","authors":"A. Jorge, M. Horbatsch, T. Kirchner","doi":"10.1103/physreva.102.012808","DOIUrl":"https://doi.org/10.1103/physreva.102.012808","url":null,"abstract":"A recently proposed classical-trajectory dynamical screening model for the description of multiple ionization and capture during ion-water molecule collisions is extended to incorporate dynamical screening on both the multi-center target potential and the projectile ion. Comparison with available experimental data for He$^{2+}$ + H$_2$O collisions at intermediate energies (10-150 keV/u) and Li$^{3+}$ + H$_2$O at higher energies (100-850 keV/u) demonstrates the importance of both screening mechanisms. The question of how to deal with the repartitioning of the capture flux into allowed capture channels is addressed. The model also provides insights for data on highly charged projectile ions (C$^{6+}$, O$^{8+}$, Si$^{13+}$) in the MeV/u range where the question of saturation effects in net ionization was raised in the literature.","PeriodicalId":8441,"journal":{"name":"arXiv: Atomic Physics","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76220279","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Influence of Laser Intensity Fluctuation on Single-Cesium Atom Trapping Lifetime in a 1064-nm Microscopic Optical Tweezer","authors":"R. Sun, Xin Wang, Kong Zhang, Jun He, Junmin Wang","doi":"10.3390/app10020659","DOIUrl":"https://doi.org/10.3390/app10020659","url":null,"abstract":"An optical tweezer composed of a strongly focused single-spatial-mode Gaussian beam of a red-detuned 1064-nm laser can confine a single-cesium (Cs) atom at the strongest point of the light intensity. We can use this for coherent manipulation of single-quantum bits and single-photon sources. The trapping lifetime of the atoms in the optical tweezers is very short due to the impact of the background atoms, the laser intensity fluctuation of optical tweezer and the residual thermal motion of the atoms. In this paper, we analyzed the influence of the background pressure, the trap frequency of optical tweezers and the parametric heating of the optical tweezer on the atomic trapping lifetime. Combined with the external feedback loop based on an acousto-optical modulator (AOM), the intensity fluctuation of the 1064-nm laser in the time domain was suppressed from $pm$ 3.360$%$ to $pm$ 0.064$%$, and the suppression bandwidth reached approximately 33 kHz. The trapping lifetime of a single Cs atom in the microscopic optical tweezer was extended from 4.04 s to 6.34 s.","PeriodicalId":8441,"journal":{"name":"arXiv: Atomic Physics","volume":"1 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2020-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"78891135","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nanosecond-timescale development of Faraday rotation in an ultracold gas","authors":"J. Gilbert, Mark Watkins, J. Roberts","doi":"10.1103/physreva.101.053848","DOIUrl":"https://doi.org/10.1103/physreva.101.053848","url":null,"abstract":"When a gas of ultracold atoms is suddenly illuminated by light that is nearly resonant with an atomic transition, the atoms cannot respond instantaneously. This non-instantaneous response means the gas is initially more transparent to the applied light than in steady-state. The timescale associated with the development of light absorption is set by the atomic excited state lifetime. Similarly, the index of refraction in the gas also requires time to reach a steady-state value, but the development of the associated phase response is expected to be slower than absorption effects. Faraday rotation is one manifestation of differing indices of refraction for orthogonal circular light polarization components. We have performed experiments measuring the time-dependent development of polarization rotation in an ultracold gas subjected to a magnetic field. Our measurements match theoretical predictions based on solving optical Bloch equations. We are able to identify how parameters such as steady-state optical thickness and applied magnetic field strength influence the development of Faraday rotation.","PeriodicalId":8441,"journal":{"name":"arXiv: Atomic Physics","volume":"43 4 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76116207","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Equation of motion for a bound system of charged particles","authors":"K. Pachucki, V. Yerokhin","doi":"10.1103/PhysRevA.100.062510","DOIUrl":"https://doi.org/10.1103/PhysRevA.100.062510","url":null,"abstract":"We consider a bound system of charged particles moving in an external electromagnetic field, including leading relativistic corrections. The difference from the point particle with a magnetic moment comes from the presence of polarizabilities. Due to the lack of separation of the total momentum from the internal degrees of freedom, the notion of polarizability of the bound state immersed in the continuum spectrum of the global motion is nontrivial. We introduce a bound-continuum perturbation theory and obtain a complete formula for the equation of motion for a polarizable bound system, such as atom, ion, or the nucleus. This formula may find applications when high precision is sought and small effects due polarizabilities are important.","PeriodicalId":8441,"journal":{"name":"arXiv: Atomic Physics","volume":"10 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84906019","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Interactions and chemical reactions in ionic alkali-metal and alkaline-earth-metal diatomic \u0000AB+\u0000 and triatomic \u0000A2B+\u0000 systems","authors":"Michal 'Smialkowski, M. Tomza","doi":"10.1103/physreva.101.012501","DOIUrl":"https://doi.org/10.1103/physreva.101.012501","url":null,"abstract":"We theoretically characterize interactions, energetics, and chemical reaction paths in ionic two-body and three-body systems of alkali-metal and alkaline-earth-metal atoms in the context of modern experiments with cold hybrid ion-atom mixtures. Using textit{ab initio} techniques of quantum chemistry such as the coupled-cluster method, we calculate ground-state electronic properties of all diatomic $AB^+$ and most of triatomic $A_2B^+$ molecular ions consisting of Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, and Yb atoms. Different geometries and wave-function symmetries of the ground state are found for different classes of molecular ions. We analyze intermolecular interactions in the investigated systems including additive two-body and nonadditive three-body ones. As an example we provide two-dimensional interaction potential energy surfaces for KRb$^+$+K and Rb$^+$+Sr$_2$ mixtures. We identify possible channels of chemical reactions based on the energetics of the reactants. The present results may be useful for investigating controlled chemical reactions and other applications of molecular ions formed in cold hybrid ion-atom systems.","PeriodicalId":8441,"journal":{"name":"arXiv: Atomic Physics","volume":"36 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-10-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85312779","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Observation of electric-dipole transitions in the laser-cooling candidate \u0000Th−\u0000 and its application for cooling antiprotons","authors":"R. Tang, R. Si, Zejie Fei, Xiaoxi Fu, Yuzhu Lu, T. Brage, Hongtao Liu, Chongyang Chen, C. Ning","doi":"10.1103/PHYSREVA.103.042817","DOIUrl":"https://doi.org/10.1103/PHYSREVA.103.042817","url":null,"abstract":"Despite the fact that the laser cooling method is a well-established technique to obtain ultra-cold neutral atoms and atomic cations, it has so far never been applied to atomic anions due to the lack of suitable electric-dipole transitions. Efforts of more than a decade currently has La$^-$ as the only promising candidate for laser cooling. Our previous work [Tang et al., Phys. Rev. Lett. 123, 203002(2019)] showed that Th$^-$ is also a potential candidate. Here we report on a combination of experimental and theoretical studies to determine the relevant transition frequencies, transition rates, and branching ratios in Th$^-$. The resonant frequency of the laser cooling transition is determined to be $nu/c$ = 4118.0 (10) cm$^{-1}$. The transition rate is calculated as A=1.17x10^4 s$^{-1}$. The branching fraction to dark states is very small, 1.47x10$^{-10}$, thus this represents an ideal closed cycle for laser cooling. Since Th has zero nuclear spin, it is an excellent candidate to be used to sympathetically cool antiprotons in a Penning trap.","PeriodicalId":8441,"journal":{"name":"arXiv: Atomic Physics","volume":"14 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89530435","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Tracing the origins of an asymmetric momentum distribution for polar molecules in strong linearly polarized laser fields","authors":"Shang Wang, J. Che, C. Chen, G. Xin, Yan-jun Chen","doi":"10.1103/physreva.102.053103","DOIUrl":"https://doi.org/10.1103/physreva.102.053103","url":null,"abstract":"We study the ionization dynamics of oriented HeH$^+$ in strong linearly-polarized laser fields by numerically solving the time-dependent Schr\"{o}dinger equation. The calculated photoelectron momentum distributions for parallel orientation show a striking asymmetric structure. With a developed model pertinent to polar molecules, we trace the electron motion in real time. We show that this asymmetric structure arises from the interplay of the Coulomb effect and the permanent dipole in strong laser fields. This structure can be used to probe the degree of orientation which is important in ultrafast experiments for polar molecules. we also check our results for other polar molecules such as CO and BF.","PeriodicalId":8441,"journal":{"name":"arXiv: Atomic Physics","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73662787","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Practical trapped-ion protocols for universal qudit-based quantum computing","authors":"Pei Jiang Low, Brendan M. White, Andrew Cox, Matthew L. Day, C. Senko","doi":"10.1103/PHYSREVRESEARCH.2.033128","DOIUrl":"https://doi.org/10.1103/PHYSREVRESEARCH.2.033128","url":null,"abstract":"The notion of universal quantum computation can be generalized to multi-level qudits, which offer advantages in resource usage and algorithmic efficiencies. Trapped ions, which are pristine and well-controlled quantum systems, offer an ideal platform to develop qudit-based quantum information processing. Previous work has not fully explored the practicality of implementing trapped-ion qudits accounting for known experimental error sources. Here, we describe a universal set of protocols for state preparation, single-qudit gates, a new generalization of the Mo{}lmer-So{}rensen gate for two-qudit gates, and a measurement scheme which utilizes shelving to a meta-stable state. We numerically simulate known sources of error from previous trapped ion experiments, and show that there are no fundamental limitations to achieving fidelities above (99%) for three-level qudits encoded in (^{137}mathrm{Ba}^+) ions. Our methods are extensible to higher-dimensional qudits, and our measurement and single-qudit gate protocols can achieve (99%) fidelities for five-level qudits. We identify avenues to further decrease errors in future work. Our results suggest that three-level trapped ion qudits will be a useful technology for quantum information processing.","PeriodicalId":8441,"journal":{"name":"arXiv: Atomic Physics","volume":"34 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85473836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Symmetric Bloch oscillations of matter waves","authors":"Z. Pagel, Weicheng Zhong, Richard H. Parker, Christopher T. Olund, N. Yao, H. Mueller","doi":"10.1103/physreva.102.053312","DOIUrl":"https://doi.org/10.1103/physreva.102.053312","url":null,"abstract":"Cold atoms in an optical lattice provide an ideal platform for studying Bloch oscillations. Here, we extend Bloch oscillations to two superposed optical lattices that are accelerated away from one another, and for the first time show that these symmetric Bloch oscillations can split, reflect and recombine matter waves coherently. Using the momentum parity-symmetry of the Hamiltonian, we map out the energy band structure of the process and show that superpositions of momentum states are created by adiabatically following the ground state of the Hamiltonian. The relative phase and velocity of the two lattices completely determines the trajectories of different branches of the matter wave. Experimentally, we demonstrate symmetric Bloch oscillations using cold Cesium atoms where we form interferometers with up to $240hbar k$ momentum splitting, one of the largest coherent momentum splittings achieved to date. This work has applications in macroscopic tests of quantum mechanics, measurements of fundamental constants, and searches for new physics.","PeriodicalId":8441,"journal":{"name":"arXiv: Atomic Physics","volume":"5 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-07-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"89012664","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Guidelines for developing optical clocks with 10-18 fractional frequency uncertainty","authors":"Moustafa Abdel-Hafiz, P. Ablewski, A. Al-Masoudi, H'ector 'Alvarez Mart'inez, P. Balling, G. Barwood, E. Benkler, M. Bober, M. Borkowski, W. Bowden, R. Ciuryło, H. Cybulski, A. Didier, Miroslav Dolevzal, S. Dorscher, S. Falke, R. Godun, R. Hamid, I. Hill, R. Hobson, N. Huntemann, Y. Coq, R. L. Targat, T. Legero, T. Lindvall, C. Lisdat, J. Lodewyck, H. Margolis, T. Mehlstaubler, E. Peik, L. Pelzer, M. Pizzocaro, B. Rauf, A. Rolland, N. Scharnhorst, M. Schioppo, P. Schmidt, R. Schwarz, cCaugri cSenel, N. Spethmann, U. Sterr, C. Tamm, J. Thomsen, A. Vianello, M. Zawada","doi":"10.15488/5553","DOIUrl":"https://doi.org/10.15488/5553","url":null,"abstract":"There has been tremendous progress in the performance of optical frequency standards since the first proposals to carry out precision spectroscopy on trapped, single ions in the 1970s. The estimated fractional frequency uncertainty of today's leading optical standards is currently in the $10^{-18}$ range, approximately two orders of magnitude better than that of the best caesium primary frequency standards. This exceptional accuracy and stability is resulting in a growing number of research groups developing optical clocks. While good review papers covering the topic already exist, more practical guidelines are needed as a complement. The purpose of this document is therefore to provide technical guidance for researchers starting in the field of optical clocks. The target audience includes national metrology institutes (NMIs) wanting to set up optical clocks (or subsystems thereof) and PhD students and postdocs entering the field. Another potential audience is academic groups with experience in atomic physics and atom or ion trapping, but with less experience of time and frequency metrology and optical clock requirements. These guidelines have arisen from the scope of the EMPIR project \"Optical clocks with $1 times 10^{-18}$ uncertainty\" (OC18). Therefore, the examples are from European laboratories even though similar work is carried out all over the world. The goal of OC18 was to push the development of optical clocks by improving each of the necessary subsystems: ultrastable lasers, neutral-atom and single-ion traps, and interrogation techniques. This document shares the knowledge acquired by the OC18 project consortium and gives practical guidance on each of these aspects.","PeriodicalId":8441,"journal":{"name":"arXiv: Atomic Physics","volume":"361 1","pages":""},"PeriodicalIF":0.0,"publicationDate":"2019-06-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76470291","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}