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Rydberg blockade, F?rster resonances, and quantum state measurements with different atomic species  [PDF]
I. I. Beterov,M. Saffman
Physics , 2015,
Abstract: We calculate interspecies Rydberg-Rydberg interaction strengths for the heavy alkalis Rb and Cs. The presence of strong F\"orster resonances makes interspecies coupling a promising approach for long range entanglement generation. We also provide an overview of the strongest F\"orster resonances for Rb-Rb and Cs-Cs using different principal quantum numbers for the two atoms. We show how interspecies coupling can be used for high fidelity quantum non demolition state measurements with low crosstalk in qubit arrays.
Effect of photoions on the line shapes of the F?rster resonance and microwave transitions in cold rubidium Rydberg atoms  [PDF]
D. B. Tretyakov,I. I. Beterov,V. M. Entin,E. A. Yakshina,I. I. Ryabtsev,S. F. Dyubko,E. A. Alekseev,N. L. Pogrebnyak,N. N. Bezuglov,E. Arimondo
Physics , 2012, DOI: 10.1134/S1063776111160102
Abstract: Experiments on the spectroscopy of the F\"orster resonance Rb(37P)+Rb(37P) -> Rb(37S)+Rb(38S) and microwave transitions nP -> n'S, n'D between Rydberg states of cold Rb atoms in a magneto-optical trap have been performed. Under ordinary conditions, all spectra exhibited a 2-3 MHz line width independently of the interaction time of atoms with each other or with microwave radiation, although the ultimate resonance width should be defined by the inverse interaction time. Analysis of the experimental conditions has shown that the main source of the line broadening was the inhomogeneous electric field of cold photoions appeared at the excitation of initial Rydberg nP states by broadband pulsed laser radiation. Using an additional pulse of the electric field, which rapidly removed the photoions after the laser pulse, lead to a substantial narrowing of the microwave and F\"orster resonances. An analysis of various sources of the line broadening in cold Rydberg atoms has been conducted.
Investigation of cold Rb Rydberg atoms in a magneto-optical trap  [PDF]
D. B. Tretyakov,I. I. Beterov,V. M. Entin,I. I. Ryabtsev,P. L. Chapovsky
Physics , 2008, DOI: 10.1134/S1063776109030029
Abstract: We present our results on the experiments with cold Rb Rydberg atoms in a magneto-optical trap (MOT). Characteristic features of our experiment were the excitation of Rydberg atoms in a small volume within the cold atom cloud and sorting of the measured signals and spectra over the number of registered Rydberg atoms. We have measured the effective lifetime of the Rydberg state 37P, as well as its polarizability in a weak electric field. The results are in good agreement with the theoretical calculations. We have shown that localization of the small excitation volume around the zero-magnetic-field point makes possible to increase the spectral resolution and to obtain narrow microwave resonances in Rydberg atoms without switching off the MOT quadrupole magnetic field. We have measured the dependence of the amplitude of the dipole-dipole interaction resonances on the number of Rydberg atoms, which has a linear character and agrees with the theory for weak dipole-dipole interaction.
Effects of molecular resonances on Rydberg blockade  [PDF]
Andrei Derevianko,Péter Kómár,Turker Topcu,Ronen M. Kroeze,Mikhail D. Lukin
Physics , 2015,
Abstract: We study the effect of resonances associated with complex molecular interaction of Rydberg atoms on Rydberg blockade. We show that densely-spaced molecular potentials between doubly-excited atomic pairs become unavoidably resonant with the optical excitation at short interatomic separations. Such molecular resonances limit the coherent control of individual excitations in Rydberg blockade. As an illustration, we compute the molecular interaction potentials of Rb atoms near the $100s$ states asymptote to characterize such detrimental molecular resonances, determine the resonant loss rate to molecules and inhomogeneous light shifts. Techniques to avoid the undesired effect of molecular resonances are discussed.
Highly resolved measurements of Stark-tuned F?rster resonances between Rydberg atoms  [PDF]
J. Nipper,J. B. Balewski,A. T. Krupp,B. Butscher,R. L?w,T. Pfau
Physics , 2012,
Abstract: We report on experiments exploring Stark-tuned F\"orster resonances between Rydberg atoms with unprecedented resolution in the F\"orster defect. The individual resonances are expected to exhibit different angular dependencies, opening the possibility to tune not only the interaction strength but also the angular dependence of the pair state potentials by an external electric field. We achieve a high resolution by optical Ramsey interferometry for Rydberg atoms combined with electric field pulses. The resonances are detected by a loss of visibility in the Ramsey fringes due to resonances in the interaction. We present measurements of the density dependence as well as of the coherence time at and close to F\"orster resonances.
Quasi-forbidden 2-body F?rster resonances in cold Cs Rydberg gas  [PDF]
Bruno Pelle,Riccardo Faoro,Juliette Billy,Ennio Arimondo,Pierre Pillet,Patrick Cheinet
Physics , 2015,
Abstract: Cold Rydberg atoms are known to display dipole-dipole interaction allowed resonances, also called F\"orster resonances, which lead to an efficient energy transfer when the proper electric field is used. This electric field also enables resonances which do not respect the dipole-dipole selection rules under zero field. A few of these quasi-forbidden resonances have been observed but they are often overlooked. Here we show that in cold $^{133}$Cs atoms there is a large number of these resonances that display a significant transfer efficiency due to their strong interactions, even at low electric field. We also develop a graphical method enabling to find all possible resonances simultaneously. The resulting dramatic increase in the total number of addressable resonant energy transfers at different electric fields could have implications in the search for few-body interactions or macro-molecules built from Rydberg atoms.
Dipole blockade through Rydberg Forster resonance energy transfer  [PDF]
Thibault Vogt,Matthieu Viteau,Jianming Zhao,Amodsen Chotia,Daniel Comparat,Pierre Pillet
Physics , 2006,
Abstract: High resolution laser excitation of np Rydberg states of cesium atoms shows a dipole blockade at F\"{o}rster resonances corresponding to the resonant dipole-dipole energy transfer of the np + np → ns + (n + 1)s reaction. The dipole-dipole interaction can be tuned on and off by the Stark effect, and such a process observed for relatively low n (25 ? 41) is promising for quantum gate devices. Both Penning ionization and saturation in the laser excitation can limit the range of observation of the dipole blockade
Ultralong-Range Rb-KRb Rydberg Molecules: Selected Aspects of Electronic Structure, Orientation and Alignment  [PDF]
Javier Aguilera-Fernández,H. R. Sadeghpour,Peter Schmelcher,Rosario González-Férez
Physics , 2015,
Abstract: We investigate the structure and features of an ultralong-range triatomic Rydberg molecule formed by a Rb Rydberg atom and a KRb diatomic molecule. In our numerical description, we perform a realistic treatment of the internal rotational motion of the diatomic molecule, and take into account the Rb($n, l\ge 3$) Rydberg degenerate manifold and the energetically closest neighboring levels with principal quantum numbers $n'>n$ and orbital quantum number $l\le2$. We focus here on the adiabatic electronic potentials evolving from the Rb($n, l\ge 3$) and Rb($n=26, l=2$) manifolds. The directional properties of the KRb diatomic molecule within the Rb-KRb triatomic Rydberg molecule are also analyzed in detail.
Enhancement of single-photon transistor by Stark-tuned F?rster resonances  [PDF]
H. Gorniaczyk,C. Tresp,P. Bienias,A. Paris-Mandoki,W. Li,I. Mirgorodskiy,H. P. Büchler,I. Lesanovsky,S. Hofferberth
Physics , 2015,
Abstract: We investigate the use of Stark-tuned F\"orster resonances to improve the efficiency of Rydberg-mediated single-photon transistors and the non-destructive detection of single Rydberg atoms. We show that our all-optical detection scheme enables high-resolution spectroscopy of two-state F\"orster resonances, revealing the fine structure splitting of high-n Rydberg states and the non-degeneracy of Rydberg Zeeman substates in finite fields. We show that the 50S_{1/2},48S_{1/2} <-> 49P_{1/2},48P_{1/2} resonance in 87Rb enables a transistor gain G > 100 and all-optical detection fidelity of single Rydberg atoms F > 0.8. Finally, we investigate the Rydberg transistor in coherent operation by reading out the gate photon after scattering source photons. We compare the observed reduction of readout efficiency to a model for the projection of the stored spin wave and phase imprinting by scattered and transmitted source photons and find very good agreement.
Spatially Resolved Excitation of Rydberg Atoms and Surface Effects on an Atom Chip  [PDF]
Atreju Tauschinsky,Rutger M. T. Thijssen,S. Whitlock,H. B. van Linden van den Heuvell,R. J. C. Spreeuw
Physics , 2010, DOI: 10.1103/PhysRevA.81.063411
Abstract: We demonstrate spatially resolved, coherent excitation of Rydberg atoms on an atom chip. Electromagnetically induced transparency (EIT) is used to investigate the properties of the Rydberg atoms near the gold coated chip surface. We measure distance dependent shifts (~10 MHz) of the Rydberg energy levels caused by a spatially inhomogeneous electric field. The measured field strength and distance dependence is in agreement with a simple model for the electric field produced by a localized patch of Rb adsorbates deposited on the chip surface during experiments. The EIT resonances remain narrow (< 4 MHz) and the observed widths are independent of atom-surface distance down to ~20 \mum, indicating relatively long lifetime of the Rydberg states. Our results open the way to studies of dipolar physics, collective excitations, quantum metrology and quantum information processing involving interacting Rydberg excited atoms on atom chips.
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