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

{"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}

{"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}

{"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}

{"title":"Nondipolar photoelectron angular distributions from fixed-in-space N2 molecules","authors":"D V Rezvan, A Pier, S Grundmann, N M Novikovskiy, N Anders, M Kircher, N Melzer, F Trinter, M S Schöffler, T Jahnke, R Dörner and Ph V Demekhin","doi":"10.1088/1361-6455/ad5893","DOIUrl":"https://doi.org/10.1088/1361-6455/ad5893","url":null,"abstract":"We investigate experimentally and theoretically the N 1s photoionization of fixed-in-space N2 molecules at a photon energy of 880 eV. In our experiment, we employed circularly polarized synchrotron radiation for the photoionization and coincident electron and fragment-ion detection using cold target recoil ion momentum spectroscopy. The accompanying angle-resolved calculations were carried out by the multichannel single-center method and code within the frozen-core Hartree–Fock approximation. The computed emission distributions exhibit two distinct features along the molecular axis, which are the results of a superposition of the direct and nearest-neighbor scattering amplitudes for the photoemission from two nitrogen atoms. In the electric-dipole approximation, these peaks are symmetric with respect to both nitrogen atoms. Including nondipole (retardation) effects in the calculations results in a simultaneous increase and decrease of the scattering peaks towards the nitrogen atoms pointing in the forward and backward directions along the light propagation, respectively. These theoretical findings are in agreement with our experimental findings.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"33 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141512343","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":"Controlling dark solitons on the healing length scale","authors":"Ling-Zheng Meng, Li-Chen Zhao, Thomas Busch and Yongping Zhang","doi":"10.1088/1361-6455/ad5895","DOIUrl":"https://doi.org/10.1088/1361-6455/ad5895","url":null,"abstract":"While usually the optical diffraction limit is setting a limit for the lengthscales on which a typical alkali Bose–Einstein condensate can be controlled, we show that in certain situations control via matter waves can achieve smaller resolutions. For this we consider a small number of impurity atoms which are trapped inside the density dip of a dark soliton state and show that any grey soliton state can be obtained by selectively driving the impurity atoms. This allows to fully control the position and velocity of the dark soliton, and also study controlled collisions between these non-linear objects.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"23 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141512344","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":"Boson bloom","authors":"G Baskaran and A R May","doi":"10.1088/1361-6455/ad3ff4","DOIUrl":"https://doi.org/10.1088/1361-6455/ad3ff4","url":null,"abstract":"The year 2024 marks the 100th anniversary of the first article on Bose statistics. Bose breathed life into the Planck distribution of radiation by a microscopic derivation (Bose 1924 Z. Phys.26 178), adding a new insight, namely indistinguishability into the then evolving quantum theory. Einstein recognized the importance of this article and got it published. Using Bose statistics Einstein wrote an article on the theory (Einstein 1924 Sutzungsber. Preuss. Akad. Wiss Phys.-Math Kl. 261) of an ideal Bose gas and Bose–Einstein condensation. The groundbreaking discovery of Bose, an unveiling of a secret of quantum mechanics, continues to reverberate after a century. Bose’s paper is considered the fourth important paper in old quantum theory, following Planck’s (1900) article (Planck 1900 Verh. Disch Phys. Ges.2 202), Einstein’s (1905) photoelectric effect (Einstein 1905 Ann. Phys., Lpz.17 132) and Bohr’s model (1913) of the atom (Bohr 1913 London, Edinburgh Dublin Phil. Mag. J. Sci.26 1). Dirac (1926 Proc. R. Soc. A 112 661) coined the name boson for one of the two families of indistinguishable particles, the other family being fermion. The edifice of modern quantum field theory, many-body quantum theory, quantum-information and quantum-computing are built on bosons, fermions and anyons. The ever-blooming quantum garden of bosons has photons, gluons, W-bosons, mesons, Higgs-bosons, gravitons, phonons, magnons, excitons, plasmons, polaritons and so on. We present a brief historical account of Bose’s life and his discovery, followed by a bird’s eye view of the impacts of bosons in modern science and technology: from Bose’s distribution of 3-degree background radiation reaching us in the form of cosmic microwave background from the big bang era to boson sampling, a novel quantum computing method. Bosogenesis before Baryogenesis?: And God said, Let there be light: and there was light (Genesis, 1:4)","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"24 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-06-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141505624","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":"Spatial calibration of high-density absorption imaging","authors":"T Vibel, M B Christensen, M A Kristensen, J J Thuesen, L N Stokholm, C A Weidner and J J Arlt","doi":"10.1088/1361-6455/ad53ae","DOIUrl":"https://doi.org/10.1088/1361-6455/ad53ae","url":null,"abstract":"The accurate determination of atom numbers is an ubiquitous problem in the field of ultracold atoms. For modest atom numbers, absolute calibration techniques are available, however, for large numbers and high densities, the available techniques neglect many-body scattering processes. Here, a spatial calibration technique for time-of-flight absorption images of ultracold atomic clouds is presented. The calibration is obtained from radially averaged absorption images and we provide a practical guide to the calibration process. It is shown that the calibration coefficient scales linearly with optical density and depends on the absorbed photon number for the experimental conditions explored here. This allows for the direct inclusion of a spatially dependent calibration in the image analysis. For typical ultracold atom clouds the spatial calibration technique leads to corrections in the detected atom number up to and temperature up to in comparison to previous calibration techniques. The technique presented here addresses a major difficulty in absorption imaging of ultracold atomic clouds and prompts further theoretical work to understand the scattering processes in ultracold dense clouds of atoms for accurate atom number calibration.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"186 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-06-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141512345","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":"Effects of p-wave interactions on Borromean Efimov trimers in heavy–light Fermi systems","authors":"Cai-Yun Zhao, Hui-Li Han, Ting-Yun Shi","doi":"10.1088/1361-6455/ad4fd2","DOIUrl":"https://doi.org/10.1088/1361-6455/ad4fd2","url":null,"abstract":"We investigate the effects of <italic toggle=\"yes\">p</italic>-wave interactions on Efimov trimers in systems comprising two identical heavy fermions and a light particle, with mass ratios larger than 13.6. Our focus lies on the Borromean regime where the ground-state trimer exists in the absence of dimers. Using pair-wise Lennard–Jones potentials and concentrating on the <inline-formula>\u0000<tex-math><?CDATA $L^{pi} = 1^{-}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mrow><mml:msup><mml:mi>L</mml:mi><mml:mrow><mml:mi>π</mml:mi></mml:mrow></mml:msup><mml:mo>=</mml:mo><mml:msup><mml:mn>1</mml:mn><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>\u0000<inline-graphic xlink:href=\"bad4fd2ieqn1.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> symmetry, we explore the critical value of the interspecies <italic toggle=\"yes\">s</italic>-wave scattering length <italic toggle=\"yes\">a</italic>\u0000_{\u0000<italic toggle=\"yes\">c</italic>\u0000} at which the Borromean state appears in several two-component particle systems. Our exploration encompasses the universal properties of <italic toggle=\"yes\">a</italic>\u0000_{\u0000<italic toggle=\"yes\">c</italic>\u0000} and the influence of <italic toggle=\"yes\">p</italic>-wave fermion–fermion interactions on its value. We find that, in the absence of <italic toggle=\"yes\">p</italic>-wave fermion–fermion interactions, <italic toggle=\"yes\">a</italic>\u0000_{\u0000<italic toggle=\"yes\">c</italic>\u0000} is determined universally by the van der Waals radius and mass ratio. However, the introduction of <italic toggle=\"yes\">p</italic>-wave fermion–fermion interactions unveiled a departure from this universality. Our calculations show that the critical interspecies scattering length <italic toggle=\"yes\">a</italic>\u0000_{\u0000<italic toggle=\"yes\">c</italic>\u0000} now depends on the details of the fermion–fermion <italic toggle=\"yes\">p</italic>-wave interaction. And, the presence of <italic toggle=\"yes\">p</italic>-wave fermion–fermion interactions favors the formation of the Borromean state. Additionally, our investigation reveals that Efimov effect in the <inline-formula>\u0000<tex-math><?CDATA $1^{-}$?></tex-math>\u0000<mml:math overflow=\"scroll\"><mml:mrow><mml:msup><mml:mn>1</mml:mn><mml:mrow><mml:mo>−</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>\u0000<inline-graphic xlink:href=\"bad4fd2ieqn2.gif\" xlink:type=\"simple\"></inline-graphic>\u0000</inline-formula> symmetry persist even when the fermion–fermion interaction reaches the <italic toggle=\"yes\">p</italic>-wave unitary limit.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"49 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-06-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141551950","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":"Introduction to theoretical and experimental aspects of quantum optimal control","authors":"Q Ansel, E Dionis, F Arrouas, B Peaudecerf, S Guérin, D Guéry-Odelin and D Sugny","doi":"10.1088/1361-6455/ad46a5","DOIUrl":"https://doi.org/10.1088/1361-6455/ad46a5","url":null,"abstract":"Quantum optimal control (QOC) is a set of methods for designing time-varying electromagnetic fields to perform operations in quantum technologies. This tutorial paper introduces the basic elements of this theory based on the Pontryagin maximum principle, in a physicist-friendly way. An analogy with classical Lagrangian and Hamiltonian mechanics is proposed to present the main results used in this field. Emphasis is placed on the different numerical algorithms to solve a QOC problem. Several examples ranging from the control of two-level quantum systems to that of Bose–Einstein condensates (BECs) in a one-dimensional optical lattice are studied in detail, using both analytical and numerical methods. Codes based on shooting method and gradient-based algorithms are provided. The connection between optimal processes and the quantum speed limit is also discussed in two-level quantum systems. In the case of BEC, the experimental implementation of optimal control protocols is described, both for two-level and many-level cases, with the current constraints and limitations of such platforms. This presentation is illustrated by the corresponding experimental results.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"72 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-06-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141258598","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":"R-Matrix calculations for opacities: II. Photoionization and oscillator strengths of iron ions Fe xvii, Fe xviii and Fe xix","authors":"S N Nahar, L Zhao, W Eissner and A K Pradhan","doi":"10.1088/1361-6455/ad4241","DOIUrl":"https://doi.org/10.1088/1361-6455/ad4241","url":null,"abstract":"Iron is the dominant heavy element that plays an important role in radiation transport in stellar interiors. Owing to its abundance and large number of bound levels and transitions, iron ions determine the opacity more than any other astrophysically abundant element. A few iron ions constitute the abundance and opacity of iron at the base of the convection zone (BCZ) at the boundary between the solar convection and radiative zones and are the focus of the present study. Together, Fe xvii, Fe xviii and Fe xix represent 85% of iron ion fractions, 20%, 39% and 26% respectively, at the BCZ physical conditions of temperature T ∼ K and electron density = c.c. We report the most extensive R-matrix atomic calculations for these ions for bound–bound and bound–free transitions, the two main processes of radiation absorption. We consider wavefunction expansions with 218 target or core ion fine structure levels of Fe xviii for Fe xvii, 276 levels of Fe xix for Fe xviii, in the Breit–Pauli R-matrix (BPRM) approximation, and 180 LS terms (equivalent to 415 fine structure levels) of Fe xx for Fe xix calculations. These large target expansions, which include core ion excitations to n = 2,3,4 complexes, enable accuracy and convergence of photoionization cross sections, as well as the inclusion of high lying resonances. The resulting R-matrix datasets include 454 bound levels for Fe xvii, 1,174 levels for Fe xviii, and 1,626 for Fe xix up to 10 and l = 0–9. Corresponding datasets of oscillator strengths for photoabsorption are: 20 951 transitions for Fe xvii, 141 869 for Fe xviii, and 289 291 for Fe xix. Photoionization cross sections have been obtained for all bound fine structure levels of Fe xvii and Fe xviii, and for 900 bound LS states of Fe xix. Selected results demonstrating prominent characteristic features of photoionization are presented, particularly the strong Seaton photoexcitation-of-core resonances formed via high-lying core excitations with that significantly impact bound–free opacity.","PeriodicalId":16826,"journal":{"name":"Journal of Physics B: Atomic, Molecular and Optical Physics","volume":"55 1","pages":""},"PeriodicalIF":1.6,"publicationDate":"2024-05-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"141061663","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}