Phase transitions are ubiquitous in our three-dimensional world. By contrast, most conventional do not occur infinite uniform low-dimensional systems because of the increased role thermal fluctuations. The crossover between these situations constitutes an important issue, dramatically illustrated by Bose-Einstein condensation: a gas strongly confined along one direction space may condense this without exhibiting true long-range order perpendicular plane. Here we explore transverse...

We create supercurrents in annular two-dimensional Bose gases through a temperature quench of the normal-to-superfluid phase transition. detect amplitude and chirality these by measuring spiral patterns resulting from interference cloud with central reference disk. These measurements demonstrate stochastic nature supercurrents. further measure their distribution for different times compare it predictions based on Kibble-Zurek mechanism.

By illuminating an individual rubidium atom stored in a tight optical tweezer with short resonant light pulses, we created efficient triggered source of single photons well-defined polarization. The measured intensity correlation the emitted pulses exhibits almost perfect antibunching. Such high-rate, fully controlled single-photon has many potential applications for quantum information processing.

We propose a realistic scheme to detect topological edge states in an optical lattice subjected synthetic magnetic field, based on generalization of Bragg spectroscopy sensitive angular momentum. demonstrate that using well-designed laser probe, the spectra provide unambiguous signature establishes their chiral nature. This is present for variety boundaries, from hard wall smooth harmonic potential added top lattice. Experimentally, signal should be very weak. To make it detectable, we...

In superfluid systems several sound modes can be excited, such as, for example, first and second in liquid helium. Here, we excite running standing waves a uniform two-dimensional Bose gas characterize the propagation of both normal regimes. phase, measured speed is good agreement with prediction two-fluid hydrodynamic model, weak damping well explained by scattering thermal excitations. phase observe stronger damping, which attribute to departure from behavior.

We consider strong two-body losses in bosonic gases trapped one-dimensional optical lattices. exploit the separation of timescales typical a system many-body quantum Zeno regime to establish connection with theory time-dependent generalized Gibbs ensemble. Our main result is simple set rate equations that capture simultaneous action coherent evolution and losses. This treatment gives an accurate description dynamics gas prepared Mott insulating state shows its long-time behavior deviates...

At zero temperature, a Galilean-invariant Bose fluid is expected to be fully superfluid. Here we investigate theoretically and experimentally the quenching of superfluid density dilute Bose-Einstein condensate due breaking translational (and thus Galilean) invariance by an external 1D periodic potential. Both Leggett's bound fixed knowledge total anisotropy sound velocity provide consistent determination fraction. The use large-period lattice emphasizes important role two-body interactions...

The optical properties of randomly positioned, resonant scatterers is a fundamentally difficult problem to address across wide range densities and geometries. We investigate it experimentally using dense cloud rubidium atoms probed with near-resonant light. are confined in slab geometry sub-wavelength thickness. probe the response as its density hence strength light-induced dipole-dipole interactions increased. also describe theoretical study based on coupled dipole simulation which further...

Topological properties of crystals and quasicrystals is a subject recent growing interest. This Letter reports an experiment where, for certain quasicrystals, these can be directly retrieved from diffraction. We observe, using interferometric approach, all the topological invariants finite-length Fibonacci chains in their diffraction pattern. also quantitatively demonstrate stability with respect to structural disorder.Received 7 July 2017DOI:https://doi.org/10.1103/PhysRevLett.119.215304©...

A fluid is said to be \emph{scale-invariant} when its interaction and kinetic energies have the same scaling in a dilation operation. In association with more general conformal invariance, scale invariance provides dynamical symmetry which has profound consequences both on equilibrium properties of time evolution. Here we investigate experimentally far-from-equilibrium dynamics cold two-dimensional rubidium Bose gas. We operate regime where gas accurately described by classical field obeying...

Most experimental observations of solitons are limited to one-dimensional (1D) situations, where they naturally stable. For instance, in 1D cold Bose gases, exist for any attractive interaction strength $g$ and particle number $N$. By contrast, two dimensions, appear only discrete values $gN$, the so-called Townes soliton being most celebrated example. Here, we use a two-component gas prepare deterministically such soliton: Starting from uniform bath atoms given internal state, imprint wave...

We demonstrate the initialization, readout, and high-speed manipulation of a qubit stored in single $^{87}\mathrm{Rb}$ atom trapped submicrometer-sized optical tweezer. Single-qubit rotations are performed on time scale below $100\phantom{\rule{0.3em}{0ex}}\mathrm{ns}$ using two-photon Raman transitions. Using spin-echo technique, we measure an irreversible dephasing $34\phantom{\rule{0.3em}{0ex}}\mathrm{ms}$. The readout is at quantum projection noise limit when averaging up to 1000...

The experimental realization of 2D Bose gases with a tunable interaction strength is an important challenge for the study ultracold quantum matter. Here we report on optical accordion creating lattice potential spacing that can be dynamically tuned between 11$\,\mu$m and 2$\,\mu$m. We show load $^{87}$Rb atoms into single node this in large configuration then decrease nearly adiabatically to reach strong harmonic confinement frequencies larger than $\omega_z/2\pi=10\,$kHz. Atoms are trapped...

Controlled quantum systems such as ultracold atoms can provide powerful platforms to study non-equilibrium dynamics of closed many-body systems, especially since a complete theoretical description is generally challenging. In this Letter, we present detailed the rich out-of-equilibrium an adjustable number $N$ uncorrelated condensates after connecting them in ring-shaped optical trap. We observe formation long-lived supercurrents and confirm scaling their winding with agreement geodesic...

Out-of-equilibrium phenomena is a subject of considerable interest in many fields physics. Ultracold quantum gases, which are extremely clean, well-isolated and highly controllable systems, offer ideal platforms to investigate this topic. The recent progress tailoring trapping potentials now allows the experimental production homogeneous samples custom geometries, key advance for studies emergence coherence interacting systems. Here we review experiments temperature quenches have been...

We have induced adiabatic transitions in pairs of frozen Rydberg sodium atoms a supersonic beam. The diatomic $ns+ns\ensuremath{\rightarrow}np+(n\ensuremath{-}1)p$ transition takes place time-dependent electric field and originates from the change internal state pair by dipole-dipole interaction. This is experimentally achieved sweeping an across energy degeneracy $ns\text{ }ns\ensuremath{-}np(n\ensuremath{-}1)p$. Our results fully agree with two-level Landau-Zener model diatom system.

We demonstrate the arbitrary control of density profile a two-dimensional Bose gas by shaping optical potential applied to atoms. use digital micromirror device (DMD) directly imaged onto atomic cloud through high resolution imaging system. Our approach relies on averaging response many pixels DMD over diffraction spot system, which allows us create an with grey levels and micron-scale resolution. The obtained distribution is optimized feedback loop based measured absorption images cloud....

We report on high-resolution optical spectroscopy of interacting bosonic $^{174}$Yb atoms in deep lattices with negligible tunneling. prepare Mott insulator phases singly- and doubly-occupied isolated sites probe the using an ultra-narrow "clock" transition. Atoms singly-occupied undergo long-lived Rabi oscillations. are strongly affected by interatomic interactions, we measure their inelastic decay rates energy shifts. deduce from these measurements all relevant collisional parameters...

We describe Doppler spectroscopy of Bose-Einstein condensates ytterbium atoms using a narrow optical transition. address the clock transition around 578 nm between ${^1}S_0$ and ${^3}P_0$ states with laser system locked on high-finesse cavity. show how absolute frequency cavity modes can be determined within few tens kHz high-resolution molecular iodine. that spectra reflect velocity distribution expanding in free fall or after releasing them inside an waveguide. demonstrate sub-kHz spectral...