An experimental approach for investigating many-body phenomena in Rydberg-interacting quantum systems

Recent developments in the study of ultracold Rydberg gases demand an advanced level of experimental sophistication, in which high atomic and optical densities must be combined with excellent control of external fields and sensitive Rydberg atom detection. We describe a tailored experimental system used to produce and study Rydberg-interacting atoms excited from dense ultracold atomic gases. The experiment has been optimized for fast duty cycles using a high flux cold atom source and a three beam optical dipole trap. The latter enables tuning of the atomic density and temperature over several orders of magnitude, all the way to the Bose-Einstein condensation transition. An electrode structure surrounding the atoms allows for precise control over electric fields and single-particle sensitive field ionization detection of Rydberg atoms. We review two experiments which highlight the influence of strong Rydberg--Rydberg interactions on different many-body systems. First, the Rydberg blockade effect is used to pre-structure an atomic gas prior to its spontaneous evolution into an ultracold plasma. Second, hybrid states of photons and atoms called dark-state polaritons are studied. By looking at the statistical distribution of Rydberg excited atoms we reveal correlations between dark-state polaritons. These experiments will ultimately provide a deeper understanding of many-body phenomena in strongly-interacting regimes, including the study of strongly-coupled plasmas and interfaces between atoms and light at the quantum level.Comment: 14 pages, 11 figures; submitted to a special issue of 'Frontiers of Physics' dedicated to 'Quantum Foundation and Technology: Frontiers and Future

Design Studies of an Electrostatic Storage Ring

Electrostatic storage rings combine a number of very interesting characteristics that make them an attractive tool in the low energy range. In contrast to magnetic rings, all of the fields in an electrostatic storage ring are completely mass independent. At the same particle energy and charge state, ions from light protons to heavy biomolecules can in principal be stored with identical field setups. A small ring for ions of energies up to 50 keV is planned to be built up at Goethe University in Frankfurt. Different designs have been calculated and the results are presented in this contribution. Furthermore, prototypes of the necessary optical elements have been manufactured and are described as well

Coherent Population Trapping with Controlled Interparticle Interactions

We investigate Coherent Population Trapping in a strongly interacting ultracold Rydberg gas. Despite the strong van der Waals interactions and interparticle correlations, we observe the persistence of a resonance with subnatural linewidth at the single-particle resonance frequency as we tune the interaction strength. This narrow resonance cannot be understood within a meanfield description of the strong Rydberg--Rydberg interactions. Instead, a many-body density matrix approach, accounting for the dynamics of interparticle correlations, is shown to reproduce the observed spectral features

Full counting statistics of laser excited Rydberg aggregates in a one-dimensional geometry

We experimentally study the full counting statistics of few-body Rydberg aggregates excited from a quasi-one-dimensional Rydberg gas. We measure asymmetric excitation spectra and increased second and third order statistical moments of the Rydberg number distribution, from which we determine the average aggregate size. Direct comparisons with numerical simulations reveal the presence of liquid-like spatial correlations, and indicate sequential growth of the aggregates around an initial grain. These findings demonstrate the importance of dissipative effects in strongly correlated Rydberg gases and introduce a way to study spatio-temporal correlations in strongly-interacting many-body quantum systems without imaging.Comment: 6 pages plus supplemen

Interaction enhanced imaging of individual atoms embedded in dense atomic gases

We propose a new all-optical method to image individual atoms within dense atomic gases. The scheme exploits interaction induced shifts on highly polarizable excited states, which can be spatially resolved via an electromagnetically induced transparency resonance. We focus in particular on imaging strongly interacting many-body states of Rydberg atoms embedded in an ultracold gas of ground state atoms. Using a realistic model we show that it is possible to image individual impurity atoms with enhanced sensitivity and high resolution despite photon shot noise and atomic density fluctuations. This new imaging scheme is ideally suited to equilibrium and dynamical studies of complex many-body phenomena involving strongly interacting atoms. As an example we study blockade effects and correlations in the distribution of Rydberg atoms optically excited from a dense gas.Comment: 5 pages plus supplementary materia

Test of the REX-RFQ and status of the front part of the REX-ISOLDE linac

For REX-ISOLDE (Radioactive beam EXperiments at ISOLDE/CERN), a test beamline is built up at the Garching Accelerator Lab. to perform He$^{1+}$-experiments with the RFQ, the matching (rebunching) section between RFQ and IH-DT-linac, the IH-structure and several electrostatic lenses of the REX-ISOLDE-mass separator. In a first step, the beamline is conceived for tests with the RFQ. This paper presents the parameters and the status of the REX-RFQ, the experimental setup and the particle dynamics simulations with the COSY infinity code for beam injection and beam analysis. Furthermore it shows the design and status of the mass separator, the IH- structure and the buncher section. (5 refs)

HITRAP: A facility at GSI for highly charged ions

An overview and status report of the new trapping facility for highly charged ions at the Gesellschaft fuer Schwerionenforschung is presented. The construction of this facility started in 2005 and is expected to be completed in 2008. Once operational, highly charged ions will be loaded from the experimental storage ring ESR into the HITRAP facility, where they are decelerated and cooled. The kinetic energy of the initially fast ions is reduced by more than fourteen orders of magnitude and their thermal energy is cooled to cryogenic temperatures. The cold ions are then delivered to a broad range of atomic physics experiments.Comment: 8 pages, 11 figure

FIRE-the Frankfurt Ion stoRage Experiments

Abstract Existing electrostatic storage rings have proven to be a valuable tool for molecular and atomic physics in the low-energy regime. At the new Stern-Gerlach Center of Frankfurt University a small machine for ion energies up to 50 keV will be build up. It will serve as a tool to analyze the structure and dynamics of many particle systems from atoms to complex organic biomolecules. It will be possible to prepare the particle beams of interest in novel and unique ways. In direct comparison to traditional setups, the luminosity of the measurements will be improved by many orders of magnitude. In combination with the newest reaction microscopes, the F rankfurt Ion stoRage Experiments (FIRE) will allow analysis of many particle fragmentation processes of atoms and molecules with unrivaled resolution and completeness. In contrast to experiments with traps, an electrostatic storage ring has the advantage of being able to record the momenta of all neutral fragments. This paper gives an overview of the design parameters, the optical elements used and the project status.