States Of Rubidium Research Articles

Exploring the vibrational series of pure trilobite Rydberg molecules

In trilobite Rydberg molecules, an atom in the ground state is bound by electron-atom scattering to a Rydberg electron that is in a superposition of high angular momentum states. This results in a homonuclear molecule with a permanent electric dipole moment in the kilo-debye range. Trilobite molecules have previously been observed only with admixtures of low-l states. Here we report on the observation of two vibrational series of pure trilobite Rubidium-Rydberg molecules that are nearly equidistant. They are produced by three-photon photoassociation and lie energetically more than 15 GHz below the atomic 22F state of rubidium. We show that these states can be used to measure the electron-atom scattering length at low energies in order to benchmark current theoretical calculations. In addition to measuring their kilo-Debye dipole moments, we also show that the molecular lifetime is increased compared to the 22F state due to the high-l character. The observation of an equidistant series of vibrational states opens the way to observe coherent molecular wave packet dynamics.

Effect of Absorption and Polarization Potentials in The Distorted Wave Calculation of Positron Impact Excitation of Autoionizing State of Rubidium

This study focuses on the scattering of positrons and rubidium atoms. We utilized the distorted wave approach to compute the cross sections and alignment parameter from near excitation threshold up to 1500 eV. Our system employed Clementi and Roetti (1974) multi-zeta Roothan-Hatree-Fock wave. We employed a complex distortion potential comprising static, absorption, and polarization terms to calculate cross sections and the alignment parameter. Our results were compared with other available studies, and we found that including polarization and absorption potentials significantly affected the cross-sections and the alignment parameter, especially at low-impact energies. These two potentials enhanced the accuracy of both the cross-section and alignment parameter results.

Interaction of blackbody radiation with rubidium and caesium atoms in small-angular-momentum Rydberg states

We examine the possibilities of refining an asymptotic description and quantitative calculations of the effects induced by thermal blackbody radiation (BBR) of the environment on the Rydberg states of atoms. Numerical values are calculated and asymptotic expressions are proposed for simplified estimates of natural lifetimes and threshold photoionisation cross sections for Rydberg states of rubidium and caesium atoms with large values of the principal quantum number, n ⩾ 20, and small orbital momenta, l = 0, 1, 2, 3. Based on analytical expressions, we present numerical estimates for the contributions of photoionisation probabilities to the BBR-induced broadening of the Rydberg energy level, as well as the contributions of continuum integrals to thermally induced shifts in the Rydberg-state energy levels.

Electron-impact excitation of the 5varvec{^2textbf{S}_{1/2} rightarrow 5^2textbf{P}_{1/2}} and 5varvec{^2textbf{P}_{3/2}} transitions in rubidium by 40 eV electrons: theory and experiment

We report on a series of detailed Breit-Pauli and Dirac B-spline R-matrix (DBSR) differential cross section (DCS) calculations for excitation of the 5,^2textrm{S}_{1/2} rightarrow 5,^2textrm{P}_{1/2} and 5,^2textrm{S}_{1/2}rightarrow 5,^2textrm{P}_{3/2} states in rubidium by 40 eV incident electrons. The early BP computations shown here were carried out with both 5 states and 12 states, while the DBSR models coupled 150 and 325 states, respectively. We also report corresponding results from a limited set of DCS measurements on the unresolved 5,^2textrm{P}_{1/2,3/2} states, with the experimental data being restricted to the scattered electron angular range 2–10^circ . Typically, good agreement is found between our calculated and measured DCS for excitation of the unresolved 5,^2textrm{P}_{1/2,3/2} states, with best accord being found between the DBSR predictions and the measured data. The present theoretical and experimental results are also compared with predictions from earlier 40 eV calculations using the nonrelativistic Distorted-Wave Born Approximation and a Relativistic Distorted-Wave model.Graphic abstract

Long-range Rydberg-atom–ion molecules of Rb and Cs

We propose a novel type of Rydberg dimer, consisting of a Rydberg-state atom bound to a distant positive ion. The molecule is formed through long-range electric-multipole interaction between the Rydberg atom and the point-like ion. We present potential energy curves (PECs) that are asymptotically connected with Rydberg $nP$- or $nD$-states of rubidium or cesium. The PECs exhibit deep, long-range wells which support many vibrational states of Rydberg-atom-ion molecules (RAIMs). We consider photo-association of RAIMs in both the weak and the strong optical-coupling regimes between initial and Rydberg states of the neutral atom. Experimental considerations for the realization of RAIMs are discussed.

Atomic Receiver by Utilizing Multiple Radio-Frequency Coupling at Rydberg States of Rubidium

Rydberg atoms have been extensively utilized in microwave measurement with high sensitivity, which has great potential in the field of communication. In this study, we discuss the digital communication based on a Rydberg atomic receiver under simultaneously coupling by resonant and near detuning microwaves. In addition, we verify the feasibility of the Rydberg atom-based frequency division multiplexing (FDM) in microwave communication. We demonstrate the principle and performance of the atom-based FDM receiver by applying amplitude modulation (AM) and frequency modulation (FM), respectively. To demonstrate the actual communication performance at different data transfer rates, we consider monochromatic images as an example. The experimental results show that the maximum acceptable data transfer rate of both AM and FM is about 200 kbps, whereas their maximum bit error rates (BER) is less than 5%. When compared with the traditional electronic receiver, this atomic receiver, which is compatible with FDM, has numerous advantages, such as small size, low power consumption, and high sensitivity. Furthermore, this receiver has a strong ability of anti-electromagnetic interference, and the signals transmitted do not interfere with each other in different channels.

Interacting Floquet polaritons.

Ordinarily, photons do not interact with one another. However, atoms can be used to mediate photonic interactions1,2, raising the prospect of forming synthetic materials3 and quantum information systems4-7 from photons. One promising approach combines highly excited Rydberg atoms8-12 with the enhanced light-matter coupling of an optical cavity to convert photons into strongly interacting polaritons13-15. However, quantum materials made of optical photons have not yet been realized, because the experimental challenge of coupling a suitable atomic sample with a degenerate cavity has constrained cavity polaritons to a single spatial mode that is resonant with an atomic transition. Here we use Floquet engineering16,17-the periodic modulation of a quantum system-to enable strongly interacting polaritons to access multiple spatial modes of an optical cavity. First, we show that periodically modulating an excited state of rubidium splits its spectral weight to generate new lines-beyond those that are ordinarily characteristic of the atom-separated by multiples of the modulation frequency. Second, we use this capability to simultaneously generate spectral lines that are resonant with two chosen spatial modes of a non-degenerate optical cavity, enabling what we name 'Floquet polaritons' to exist in both modes. Because both spectral lines correspond to the same Floquet-engineered atomic state, adding a single-frequency field is sufficient to couple both modes to a Rydberg excitation. We demonstrate that the resulting polaritons interact strongly in both cavity modes simultaneously. The production of Floquet polaritons provides a promising new route to the realization of ordered states of strongly correlated photons, including crystals and topological fluids, as well as quantum information technologies such as multimode photon-by-photon switching.

Trapping of Rydberg atoms in tight magnetic microtraps

We explore the possibility to trap Rydberg atoms in tightly confining magnetic microtraps. The trapping frequencies for Rydberg atoms are expected to be influenced strongly by magnetic field gradients. We show that there are regimes where Rydberg atoms can be trapped. Moreover, we show that so-called magic trapping conditions can be found for certain states of rubidium, where both Rydberg atoms and ground state atoms have the same trapping frequencies. Magic trapping is highly beneficial for implementing quantum gate operations that require long operation times.

Determination of hyperfine structure constants of 5D5/2 and 7S1/2 states of rubidium in cascade atomic system

We present a method to precisely determine the hyperfine structure constants of the rubidium 5D5/2 and 7S1/2 states in a cascade atomic system. The probe laser is coupled to the 5S1/2→5P3/2 hyperfine transition, while the coupling laser is scanned over the 5P3/2→5D5/2(7S1/2) transition. The high-resolution double-resonance optical pumping spectra are obtained with two counter-propagating laser beams acting on rubidium vapor. The hyperfine splitting structures are accurately measured by an optical frequency ruler based on the acousto-optic modulator, thus, the magnetic dipole hyperfine coupling constant A and quadrupole coupling constant B are determined. It is of great significance for the atomic hyperfine structure and fundamental physics research.

Control of rubidium low-lying Rydberg states with trichromatic femtosecond π pulses for ultrafast quantum information processing

We propose an ultrafast femtosecond time scale trichromatic $\ensuremath{\pi}$-pulse illumination scheme for coherent excitation and manipulation of low-lying Rydberg states in rubidium. Selective population of ${nP}_{3/2}$ levels with principal quantum numbers $n\ensuremath{\lesssim}12$ using 75-fs laser pulses is achieved. The density-matrix equations of a four-level ladder system beyond the rotating-wave approximation have to be solved to clarify the balance between the principal quantum numbers, the duration of the laser pulses, and the associated ac-Stark effects for the fastest optimal excitation. The mechanism is robust for femtosecond control using different level configurations for applications in ultrafast quantum information processing and spectroscopy.

Ionization spectra of highly Stark-shifted rubidium Rydberg states

We report on the observation and numerical calculation of ionization spectra of highly Stark-shifted Rydberg states of rubidium beyond the classical ionization threshold. In the numerical calculations, a complex absorbing potential (CAP) allows us to predict the energy levels and ionization rates of Rydberg states in this regime. Our approach of adjusting the CAP to the external electric field reduces the number of free parameters from one per resonance to a single one. Furthermore, we have measured the ionization spectra of magneto-optically trapped rubidium atoms which are excited to principal quantum numbers of 43 and 70 at various electric fields. The emerging ions are detected using an ion optics. We find good agreement between the numerically and experimentally obtained spectra.

Effect of Exchange and Absorption Potential in the Distorted Wave Calculation of Electron Impact Excitation of Auto Ionizing State of Rubidium

A thesis is submitted in the partial fulfillment of the requirements for the award of the degree of Masters of Sciencein the School of Pure and Applied Sciences of Kenyatta University September, 2017

Spectrum, radial wave functions, and hyperfine splittings of the Rydberg states in heavy alkali-metal atoms

We calculate the bound state spectrum of the highly excited valence electron in the heavy alkali atoms solving the radial Schr\"odinger eigenvalue problem numerically with an accurate spectral collocation algorithm that applies also for a large principal quantum number $n\gg1$. As an effective single-particle potential we favor the reputable potential of Marinescu \emph{et al}., {[}Phys. Rev.A \textbf{49}, 982(1994){]}. Recent quasiclassical calculations of the quantum defect of the valence electron agree for orbital angular momentum $l=0,1,2,...$ overall remarkably well with the results of the numerical calculations, but for the Rydberg states of rubidium and also cesium with $l=3$ this agreement is less fair. The reason for this anomaly is that the potential acquires for $l=3$ deep inside the ionic core a tiny second classical region, thus invalidating a standard WKB calculation with two widely spaced turning points. Comparing then our numerical solutions of the radial Schr\"odinger eigenvalue problem with the uniform analytic WKB approximation of Langer we observe everywhere a remarkable agreement, apart from a tiny region around the inner turning point. With help of an ansatz proposed by Fock we obtain for the \emph{s}-states a second uniform analytic approximation to the radial wave function complementary to the WKB approximation of Langer, which is exact for $r\to0^{+}$. The value of the radial \emph{s}-wave function at $r=0$ is analytically found, thus validating the Fermi-Segr\`e formula for the magnetic dipole interaction constant $A_{n,j,0}^{\left(\mathrm{HFS}\right)}$.

Coupling of four-wave mixing and Raman scattering by ground-state atomic coherence

We demonstrate coupling of light resonant to transition between two excited states of rubidium and long-lived ground-state atomic coherence. In our proof-of-principle experiment a non-linear process of four-wave mixing is used to achieve light emission proportional to independently prepared ground-state atomic coherence. Strong correlations between stimulated Raman scattering light heralding generation of ground-state coherence and the four-wave mixing signal are measured and shown to survive the storage period, which is promising in terms of quantum memory applications. The process is characterized as a function of laser detunings.

Excitation and ionization of outer shells in Rb by electron impact

The relativistic distorted-wave and binary-encounter-dipole approximations were employed for calculating the electron-impact single ionization cross sections of the 5s, 4p6, 4s2, 3d10 shells and 4p6 excitation cross section for Rb atom taking into account both configuration interaction and relativistic effects. The capabilities of the most used theoretical approaches in describing the single ionization of Rb atom were considered by comparing the present and other available calculated data with the experimental total ionization and total direct single ionization cross sections over the electron-impact energy range from the 5s threshold to 600 eV. The best agreement within experimental uncertainty was obtained by using the non-relativistic binary-encounter-dipole approximation included in the LANL Atomic Physics Codes package. At present none of the used approximations (plane-wave Born or relativistic distorted wave) can satisfactorily describe the experimental excitation-autoionization cross section in rubidium because the efficient formation of the 4p6 core-excited negative-ion rubidium states at near-threshold impact energies is ignored in calculations.

Calculation of fine-structure splittings in high-lyingF2states of rubidium

We present relativistic many-body calculations of the fine-structure splittings of the $n\phantom{\rule{0.16em}{0ex}}{}^{2}F$ Rydberg states of Rb $(n=4$--16) using both order-by-order relativistic many-body perturbation theory (RMBPT), up to a subset of fourth-order corrections, and relativistic equation-of-motion coupled-cluster methods, including singles, doubles, and an approximate treatment of valence triples. Good overall agreement is found with the measurements of Brandenberger et al. [Phys. Rev. A 65, 042510 (2002); Phys. Rev. A 81, 032515 (2010)] to better than the 1% level, which is our expected level of theoretical uncertainty due to omitted higher-order correlation effects. It is shown that the RMBPT of the fine-structure splittings is complex and slowly convergent, and that relativistic effects are enhanced compared with the RMBPT of the ionization energy of the $^{2}\mathrm{F}$ states. We also analyze smaller field-theoretic contributions to the fine-structure splittings from retardation and the radiative self-energy and vacuum polarization, finding them to enter at the 0.1% level.

Electron impact excitation of 5p states of rubidium at 20 eV incident energy

The coupled-channel optical method (CCOM) is implemented in this work to study the scattering of electron on rubidium atom at 20 eV. In order to provide a realistic calculation, the continuum effect of the scattering system is accounted by incorporate an ab initio optical potential into the CCOM calculation. The differential cross sections (DCS), as well as the reduced Stokes parameters of 5p excitation are reported and compared to the available experimental and theoretical data.

Energy spectra of scattered electrons of rubidium atoms

The energy spectra of autoionizing and scattered electrons due to excitation of the 4p6 subshell of rubidium atoms by electron impact were measured. The experimental and theoretical analysis of the obtained spectra was performed. Three metastable states of rubidium atoms were found and their basic parameters were obtained. The excitation energies and classification were compared with the data of other authors. Keywords: atom, autoionization, excitation, energy-loss spectra.

Measurement of87Rb Rydberg-state hyperfine splitting in a room-temperature vapor cell

We present direct measurements of the hyperfine splitting of Rydberg states in rubidium 87 using Electromagnetically Induced Transparency (EIT) spectroscopy in a room-temperature vapour cell. With this method, and in spite of Doppler-broadening, line-widths of 3.7 MHz FWHM, i.e. significantly below the intermediate state natural linewidth are reached. This allows resolving hyperfine splittings for Rydberg s-states with n=20...24. With this method we are able to determine Rydberg state hyperfine splittings with an accuracy of approximately 100 kHz. Ultimately our method allows accuracies of order 5 kHz to be reached. Furthermore we present a direct measurement of hyperfine-resolved Rydberg state Stark-shifts. These results will be of great value for future experiments relying on excellent knowledge of Rydberg-state energies and

Rubidium on Helium Droplets: Analysis of an Exotic Rydberg Complex for n* < 20 and 0 ≤ l ≤ 3.

Rubidium atom Rydberg states perturbed by helium droplets of different sizes provide insight into the role of a nanosized dielectric on the Coulomb potential. The observation of droplet size-dependent shifts of excited states with respect to bare atom states is explained by a decreased quantum defect and a lowered ionization threshold. Within the scope of a Rydberg model, we demonstrate that quantum defects and ionization potentials are constant for each specific Rydberg series, which confirms the Rydberg character of excited Rubidium states on helium droplets. A set of six Rydberg series could be identified. Individual Rydberg states are observed with effective principal quantum numbers up to n* ≈ 19 and l ≤ 3, for which the expectation value of the electron orbital radius is about 10 times larger than the droplet radius.