Ultracold LiCs molecules in the absolute ground state X$^1\Sigma^+$, v"=0, J"=0 are formed via a single photo-association step starting from laser-cooled atoms. The selective production of J"=2 with 50-fold higher rate is also demonstrated. rotational and vibrational determined setup combining depletion spectroscopy resonant-enhanced multi-photon ionization time-of-flight spectroscopy. Using up to 5x10^3 molecules/s, we describe simple scheme which can provide large samples externally...

We report on the observation of ultralong range interactions in a gas cold rubidium Rydberg atoms. The van der Waals interaction between pair atoms separated as far 100 000 Bohr radii features two important effects: spectral broadening resonance lines and suppression excitation with increasing density. density dependence these effects is investigated detail for $S$- $P$-Rydberg states principal quantum numbers $\mathsf{n}\ensuremath{\sim}60$ $\mathsf{n}\ensuremath{\sim}80$ excited by...

Anion-molecule nucleophilic substitution (S(N)2) reactions are known for their rich reaction dynamics, caused by a complex potential energy surface with submerged barrier and weak coupling of the relevant rotational-vibrational quantum states. The dynamics S(N)2 Cl- + CH3I were uncovered in detail using crossed molecular beam imaging. As function collision energy, transition from complex-mediated mechanism to direct backward scattering I- product was observed experimentally. Chemical...

We observe two consecutive heteronuclear Efimov resonances in an ultracold Li-Cs mixture by measuring three-body loss coefficients as a function of magnetic field near Feshbach resonance. The first resonance is detected at scattering length a_((0))=-320(10)a_((0)), corresponding to ∼7(∼3) times the (Cs-Cs) van der Waals range. second appears 5.8(1.0)a_((0)), close unitarity-limited regime sample temperature 450 nK. Indication third found atom spectra. scaling positions predicted universal...

We use the resonant dipole-dipole interaction between Rydberg atoms and a periodic external microwave field to engineer XXZ spin Hamiltonians with tunable anisotropies. The are placed in 1D 2D arrays of optical tweezers, allowing us study iconic situations physics, such as implementation Heisenberg model square arrays, transport 1D. first benchmark Hamiltonian engineering for two atoms, then demonstrate freezing magnetization on an initially magnetized array. Finally, we explore dynamics...

We have calculated the long-range interaction potential curves of highly excited Rydberg atom pairs for combinations Li–Li, Na–Na, K–K, Rb–Rb and Cs–Cs in a perturbative approach. The dispersion C-coefficients are determined all symmetries molecular states that correlate to ns–ns, np–np nd–nd asymptotes. Fitted parameters given scaling as function principal quantum number n homonuclear alkali metal atoms.

We experimentally study the use of two-dimensional magneto-optical trapping (2D-MOT) for generation slow beams cold atoms out a vapor cell. A particularly high flux $9\ifmmode\times\else\texttimes\fi{}{10}^{9}$ rubidium atoms/s at mean velocity 8 m/s is obtained using combination in two dimensions and Doppler cooling third dimension $({2\mathrm{D}}^{+}\ensuremath{-}\mathrm{MOT}).$ The resulting width distribution 3.3 [full half maximum (FWHM)] with beam divergence 43 mrad (FWHM). investigate...

Electronically highly excited (Rydberg) atoms experience quantum state-changing interactions similar to Förster processes found in complex molecules, offering a model system study the nature of dipole-mediated energy transport under influence controlled environment. We demonstrate nondestructive imaging method monitor migration electronic excitations with high time and spatial resolution, using electromagnetically induced transparency on background gas acting as an amplifier. The continuous...

We present the experimental observation of antiblockade in an ultracold Rydberg gas recently proposed by Ates et al. [Phys. Rev. Lett. 98, 023002 (2007)]. Our approach allows control pair distribution and is based on a strong coupling one transition atomic three-level system, while introducing specific detunings other transition. When energy matches interaction long-range interactions, otherwise blocked excitation close pairs becomes possible. A time-resolved spectroscopic measurement...

We experimentally study the full counting statistics of few-body Rydberg aggregates excited from a quasi-one-dimensional atomic gas. measure asymmetric excitation spectra and increased second third order statistical moments number distribution, which we determine average aggregate size. Estimating rates for different processes conclude that grow sequentially around an initial grain. Direct comparison with numerical simulations confirms this conclusion reveals presence liquidlike spatial...

The highly exoergic nucleophilic substitution reaction F– + CH3I shows dynamics strikingly different from that of reactions larger halogen anions. Over a wide range collision energies, large fraction indirect scattering via long-lived hydrogen-bonded complex is found both in crossed-beam imaging experiments and direct chemical simulations. Our measured differential cross sections show large-angle low product velocities for all resulting efficient transfer the energy to internal CH3F product....

Controlling interactions is the key element for quantum engineering of many-body systems. Using time-periodic driving, a naturally given Hamiltonian closed system can be transformed into an effective target that exhibits vastly different dynamics. We demonstrate such Floquet with spins represented by Rydberg states in ultracold atomic gas. By applying sequence spin manipulations, we change symmetry properties Heisenberg XYZ Hamiltonian. As consequence, relaxation behavior total drastically...

Understanding the dynamics of strongly interacting disordered quantum systems is one most challenging problems in modern science, due to features such as breakdown thermalization and emergence glassy phases matter. We report on observation anomalous relaxation an isolated XXZ spin system realized by ultracold gas atoms initially prepared a superposition two-different Rydberg states. The total magnetization found exhibit sub-exponential analogous classical dynamics, but case this originates...

We observe Bragg diffraction of blue (422 nm) radiation from ultracold rubidium atoms bound in an infrared (780 optical lattice thus demonstrating the long range periodic order these atomic lattices. The light is reflected [201] planes a cubic body-centered at incidence angle 57\ifmmode^\circ\else\textdegree\fi{}. angular breadth resonance limited by size to less than 0.26 mrad. use combination with additional weak probe beam as novel tool selectively study motion deeply potential wells.

We present time-resolved spectroscopic measurements of Rydberg-Rydberg interactions in an ultracold gas, revealing the pair dynamics induced by long-range van der Waals between atoms. By detuning excitation laser, a specific distribution is prepared. Penning ionization on microsecond timescale serves as probe for under influence attractive forces. Comparison with Monte Carlo model not only explains all features but also gives quantitative information about interaction potentials. The results...

Ultracold collisions between Cs atoms and Cs2 dimers in the electronic ground state are observed an optically trapped gas of molecules. The molecules formed triplet by cw photoassociation through outer well 0-(g) (P3/2) excited state. Inelastic atom-molecule converting internal excitation into kinetic energy lead to a loss from dipole trap. Rate coefficients determined for involving either F=3 or F=4 hyperfine state, highly vibrationally states (nu'=32-47) low vibrational (nu'=4-6) a3...

The rapid development of experimental techniques to produce ultracold alkali molecules opens the ways manipulate them and control their dynamics using external electric fields. A prerequisite quantity for such studies is knowledge static dipole polarizability. In this paper, we computed variations with internuclear distance vibrational index polarizability components all homonuclear dimers including Fr2, heteronuclear involving Li Cs, in electronic ground state lowest triplet state. We use...

We present a scheme for stabilizing the difference frequency of two independent lasers. The is based on simple electronics and makes use frequency-dependent phase shift experienced by signal when it propagates through delay line coaxial cable. stabilized can be tuned over wide range. Difference frequencies in radio-frequency domain (100 MHz–10 GHz) controlled with long-term stability better than 1 MHz.

We simultaneously trap ultracold lithium and cesium atoms in an optical dipole formed by the focus of a CO2 laser study exchange thermal energy between gases. The optically cooled gas efficiently decreases temperature through sympathetic cooling. Equilibrium temperatures down to 25 microK have been reached. measured cross section for thermalizing 133Cs-7Li collisions is 8 x 10(-12) cm(2), both species unpolarized their lowest hyperfine ground state. Besides thermalization, we observe...

Ion imaging experiments and direct chemical dynamics simulations were performed to study the atomic-level for F− + CH3I → FCH3 I− SN2 nucleophilic substitution reaction at 0.32 eV collision energy. The reproduce product energy partitionings velocity scattering angle distribution measured in experiments. reveal that occurs by two mechanisms, is, rebound stripping, an indirect mechanism. Approximately 90% of events occur via a prereaction F−···HCH2I hydrogen-bonded complex. This mechanism may...

We demonstrate the coherent excitation of a mesoscopic ensemble about 100 ultracold atoms to Rydberg states by driving Rabi oscillations from atomic ground state. employ dedicated beam shaping and optical pumping scheme compensate for small transition matrix element. study in weakly interacting regime strong interactions. When increasing interaction strength pair state resonances, we observe an increased rate through coupling high angular momentum states. This effect is contrast proposed...

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