Bulletin of the American Physical Society
47th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 61, Number 8
Monday–Friday, May 23–27, 2016; Providence, Rhode Island
Session T9: Rydberg Molecules and Dressing |
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Chair: Duncan Tate, Colby College Room: 556AB |
Friday, May 27, 2016 8:00AM - 8:12AM |
T9.00001: Ultracold Long-Range Rydberg Molecules with Complex Multichannel Spectra Matthew Eiles, Chris Greene A generalized class of exotic long-range Rydberg molecules consisting of a multichannel Rydberg atom bound to a distant ground state atom by the Rydberg electron is predicted. These molecules are characterized by the rich physics provided by the strongly perturbed multichannel Rydberg spectra of divalent atoms, in contrast to the regular Rydberg series of the alkali atoms used to form Rydberg molecules to date. These multichannel Rydberg molecules exhibit favorable properties for laser excitation, because states exist where the quantum defect varies strongly with the principal quantum number $n$. In particular, the $nd$ Rydberg state of calcium becomes nearly degenerate with states of high orbital angular momentum over the range $17 |
Friday, May 27, 2016 8:12AM - 8:24AM |
T9.00002: Direct excitation of butterfly states in Rydberg molecules Carsten Lippe, Thomas Niederpruem, Oliver Thomas, Tanita Eichert, Herwig Ott Since their first theoretical prediction Rydberg molecules have become an increasing field of research. These exotic states originate from the binding of a ground state atom in the electronic wave function of a highly-excited Rydberg atom mediated by a Fermi contact type interaction. A special class of long-range molecular states, the butterfly states, were first proposed by Greene et al.\footnote{Chris H. Greene, A. S. Dickinson, H. R. Sadeghpour, \textbf{PRL} 85, 2458}. These states arise from a shape resonance in the p-wave scattering channel of a ground state atom and a Rydberg electron and are characterized by an electron wavefunction whose density distribution resembles the shape of a butterfly. We report on the direct observation of deeply bound butterfly states of Rydberg molecules of $^{87}$Rb. The butterfly states are studied by high resolution spectroscopy of UV-excited Rydberg molecules. We find states bound up to $-50\:$GHz from the 25P$_{1/2}, F=1$ state, corresponding to binding lengths of $50\:a_0$ to $500\:a_0$ and with permanent electric dipole moments of up to $500\:$Debye. This distinguishes the observed butterfly states from the previously observed long range Rydberg molecules in rubidium. [Preview Abstract] |
Friday, May 27, 2016 8:24AM - 8:36AM |
T9.00003: Lifetimes of ultra-long-range strontium Rydberg molecules F. Camargo, J. D. Whalen, R. Ding, H. R. Sadeghpour, S. Yoshida, J. Burgdorfer, F. B. Dunning, T. C. Killian The lifetimes of the lower-lying vibrational states of ultralong-range strontium Rydberg molecules comprising one ground-state $5\textup{s}^2~ ^1 \textup{S}_0$ atom and one Rydberg atom in the $5\textup{s}38\textup{s}~ ^3\textup{S}_1$ state are reported. The molecules are created in an ultracold gas held in an optical dipole trap and their numbers determined using field ionization, the product electrons being detected by a microchannel plate. The measurements show that, in marked contrast to earlier measurements involving rubidium Rydberg molecules, the lifetimes of the low-lying molecular vibrational states are very similar to those of the parent Rydberg atoms. This results because the strong p-wave resonance in low-energy electron-rubidium scattering, which strongly influences the rubidium molecular lifetimes, is not present for strontium. The absence of this resonance offers advantages for experiments involving strontium Rydberg atoms as impurities in quantum gases and for testing theories of molecular formation and decay. [Preview Abstract] |
Friday, May 27, 2016 8:36AM - 8:48AM |
T9.00004: Molecular Spectra in an Ultracold Strontium Rydberg Gas Joseph D. Whalen, Francisco Camargo, Roger Ding, Germano Woehl Jr., F. Barry Dunning, Thomas C. Killian The interaction between a ground state atom and a highly excited Rydberg electron creates a potential that can support ultra-long-range bound molecular states comprising a Rydberg atom and several ground-state atoms. We excite these molecular states using two-photon spectroscopy in an ultracold gas of $^{84}$Sr. In a thermal gas, we observe a highly structured spectrum of many-body bound states with one Rydberg atom and as many as three ground-state atoms in various vibrational levels. We also describe the spectrum in a dense, quantum degenerate gas, which is sensitive to the properties of the polaron formed by the binding of many atoms in the quantum gas to the Rydberg impurity [1]. Because of the absence of a p-wave shape resonance in e-Sr scattering, the molecular spectrum in Sr provides a sensitive probe of the excitation dynamics in a quantum gas in a different regime than is accessible using Rb [2]. \\ $\left[1\right]$ R. Schmidt et al, arXiv: 1510.09183\\ $[2]$ M. Schlagmüller et al, arXiv: 1510.07003 [Preview Abstract] |
Friday, May 27, 2016 8:48AM - 9:00AM |
T9.00005: Cesium Ultra-Long-Range Rydberg Molecules and Many-Body Physics Jin Yang, Akbar Jahangiri, Seth Rittenhouse, Margarita Reschke, Donald Booth, Hossein Sadeghpour, James Shaffer Ultra-long-range Rydberg molecules have received increasing interest recently because of their novel properties such as the ability to serve as an electron trap, the potential to possess kilo-Debye dipole moments, and their unique binding mechanism. Recently, experiments focusing on Rydberg P-state and D-state molecules have revealed interesting new features of these novel molecules, like coupling between singlet and triplet scattering channels, p-wave scattering dominated states and their behavior in magnetic fields. In this presentation, we report our recent observation of Cesium D-state ultra-long-range Rydberg molecules and compare our observations to theoretical calculations. We also report our preliminary data on ``polymer'' molecules, which are formed by one Cs Rydberg atom but more than one Cs ground state atom. The transition from a few-body system to a many-body system can provide insight into many-body physics. [Preview Abstract] |
Friday, May 27, 2016 9:00AM - 9:12AM |
T9.00006: Anomalous broadening in driven dissipative Rydberg systems Thomas Boulier, Elizabeth Goldschmidt, Roger Brown, Silvio Koller, Jeremy Young, Alexey Gorshkov, Steven Rolston, James Porto Due to their strong, long-range, coherently-controllable interactions, Rydberg atoms have been proposed as a basis for quantum information processing and simulation of many-body physics. Using the coherent dynamics of such highly excited atomic states, however, requires addressing challenges posed by the dense spectrum of Rydberg levels, the detrimental effects of spontaneous emission, and strong interactions. We report the observation of interaction-induced broadening of the two-photon 5s-18s Rydberg transition in ultra-cold 87Rb atoms, trapped in a 3D optical lattice. The measured linewidth increases by nearly two orders of magnitude with increasing atomic density and excitation strength, with corresponding suppression of resonant scattering and enhancement of off-resonant scattering. We attribute the increased linewidth to resonant dipole-dipole interactions of 18s atoms with spontaneously created populations of nearby Rydberg p-states. This dephasing mechanism implies that the timescales available for the coherent addressing of such systems are dramatically shortened, hampering many recent proposals to use Rydberg-dressed atoms for quantum simulation. [Preview Abstract] |
Friday, May 27, 2016 9:12AM - 9:24AM |
T9.00007: Accessing Rydberg-dressed interactions using many-body Ramsey dynamics Rick Mukherjee, Thomas Killian, Kaden Hazzard We demonstrate that Ramsey spectroscopy can be used to observe Rydberg-dressed interactions in a many-body system. Our scheme operates comfortably within experimentally measured lifetimes, and accesses a regime where quantum superpositions are crucial. We build a spin-1/2 from one level that is Rydberg-dressed and another that is not. These levels may be hyperfine or long-lived electronic states. An Ising spin model governs the Ramsey dynamics, for which we derive an exact solution. Due to the structure of Rydberg interactions, the dynamics differs significantly from that in other spin systems. As one example, spin echo can \textit{increase} the rate at which coherence decays. The results are relevant for the current ongoing experiments, including those at Rice University. [Preview Abstract] |
Friday, May 27, 2016 9:24AM - 9:36AM |
T9.00008: Experimental demonstration of Rydberg dressing in a many-body system Johannes Zeiher, Peter Schauss, Sebastian Hild, Antonio Rubio-Abadal, Jae-yoon Choi, Rick van Bijnen, Thomas Pohl, Immanuel Bloch, Christian Gross Rydberg atoms offer the possibility to study long range interacting systems of ultracold atoms due to their strong van der Waals interactions. Admixture of a Rydberg state to a ground state, known as Rydberg dressing, allows for increased experimental tunability of these interactions and promises to study novel phases of matter.\\ Here we report on our results of the realization of Rydberg dressing in a many-body spin system. Starting from a two-dimensional spin-polarized Mott insulator of an ultracold gas of rubidium-87, we optically couple one spin component to a Rydberg p-state on a single photon ultra-violet transition at $297\,\mathrm{nm}$. Using microwave Ramsey interferometry in the ground state manifold, we measure the spin-spin correlations emerging due to the admixture of long range interactions to the ground state. To show the predicted versatility of Rydberg dressing, we tune the range and anisotropy of the interaction. We furthermore discuss loss processes affecting our dressed ensembles and present initial indications of improved lifetimes in our system. \\ Our results constitute an important step towards the realization of novel spin models with Rydberg dressed interactions. [Preview Abstract] |
Friday, May 27, 2016 9:36AM - 9:48AM |
T9.00009: Charge Transfer in Ultracold Rydberg-Ground State Atomic Collisions Samuel Markson, Hossein Sadeghpour In excited molecules, the interaction between the covalent Rydberg and ion-pair channels forms a unique class of excited Rydberg states, in which the infinite manifold of vibrational levels are the equivalent of atomic Rydberg states with a heavy electron mass. Here, we develop an analytical, asymptotic charge transfer model for the interaction between ultracold Rydberg molecular states, and employ this method to demonstrate the utility of off-resonant field control over the ultracold ion-pair formation, with near unity efficiency. [Preview Abstract] |
Friday, May 27, 2016 9:48AM - 10:00AM |
T9.00010: Formation rate for Rb${}_2^+$ molecular ions created in collisions of Rb Rydberg and ground-state atoms Jovica Stanojevic, Robin C\^ot\'e We calculate the formation rate of the molecular Rb${}_2^+$ ion in its various bound states produced in the associative ionization of a Rydberg and a ground-state atom. Before the formation takes place, the colliding atoms are accelerated by an attractive force between the collision partners. In this way the ground-state atom is first captured by the Rydberg electron and then guided towards the positive ion-core where a molecular ion is subsequently formed. As recently demonstrated [1], this process results in giant collisional cross sections for the molecular ion formation, with the cross sections essentially determined by the size of the Rydberg atom. For sufficient high principal quantum numbers and atomic densities, many ground-state atoms are already located inside the Rydberg atom [2] and ready to participate in the associative ionization. The same process can occur between a Rydberg and a ground-state atom that form a long-range Rydberg molecule, possibly contributing to the shortening of the lifetimes of Rydberg atoms and molecules. \\[1ex] [1] T. Niederpr\"um et al., Phys. Rev. Lett. {\bf 115}, 013003 (2015). \\{} [2] J. B. Balewski et al., Nature {\bf 502}, 664 (2013). [Preview Abstract] |
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