Lucas Béguin

Direct Measurement of the van der Waals Interaction between Two Rydberg Atoms

We report on the direct measurement of the van der Waals interaction between two isolated, single Rydberg atoms separated by a controlled distance of a few micrometers. By working in a regime where the single-atom Rabi frequency of the laser used for excitation to the Rydberg state is comparable to the interaction energy, we observe a \emph{partial} Rydberg blockade, whereby the time-dependent populations of the various two-atom states exhibit coherent oscillations with several frequencies. A quantitative comparison of the data with a simple model based on the optical Bloch equations allows us to extract the van der Waals energy, and to observe its characteristic

Demonstration of a strong Rydberg blockade in three-atom systems with anisotropic interactions.

C_6/R^6

Single-Atom Trapping in Holographic 2D Arrays of Microtraps with Arbitrary Geometries

dependence. The magnitude of the measured

An artificial Rb atom in a semiconductor with lifetime-limited linewidth

C_6

Single-atom addressing in microtraps for quantum-state engineering using Rydberg atoms

coefficient agrees well with an \emph{ab-initio} theoretical calculation, and we observe its dramatic increase with the principal quantum number

An atomic memory suitable for semiconductor quantum dot single photons

n

Coherent dipole-dipole coupling between two single Rydberg atoms at an electrically-tuned Forster resonance

of the Rydberg state. Our results not only allow to test an important physical law, but also demonstrate a degree of experimental control which opens new perspectives in quantum information processing and quantum simulation using long-range interactions between the atoms.

Simple Atomic Quantum Memory Suitable for Semiconductor Quantum Dot Single Photons

We study the Rydberg blockade in a system of three atoms arranged in different two-dimensional geometries (linear and triangular configurations). In the strong blockade regime, we observe high-contrast, coherent collective oscillations of the single excitation probability and an almost perfect van der Waals blockade. Our data are consistent with a total population in doubly and triply excited states below 2%. In the partial blockade regime, we directly observe the anisotropy of the van der Waals interactions between |nD> Rydberg states in the triangular configuration. A simple model that only uses independently measured two-body van der Waals interactions fully reproduces the dynamics of the system without any adjustable parameter. These results are extremely promising for scalable quantum information processing and quantum simulation with neutral atoms.

Coherent dipole-dipole coupling between two single atoms at a F\"orster resonance

We demonstrate single-atom trapping in two-dimensional arrays of microtraps with arbitrary geometries. We generate the arrays using a Spatial Light Modulator (SLM), with which we imprint an appropriate phase pattern on an optical dipole trap beam prior to focusing. We trap single

Measurement of the van der Waals Interaction between Two Rydberg Atoms

^{87}{\rm Rb}