Lattice Interferometer for Ultra-Cold Atoms

We demonstrate an atomic interferometer based on ultra-cold atoms released from an optical lattice. This technique yields a large improvement in signal to noise over a related interferometer previously demonstrated. The interferometer involves diffraction of the atoms using a pulsed optical lattice. For short pulses a simple analytical theory predicts the expected signal. We investigate the interferometer for both short pulses and longer pulses where the analytical theory break down. Longer pulses can improve the precision and signal size. For specific pulse lengths we observe a coherent signal at times that differs greatly from what is expected from the short pulse model. The interferometric signal also reveals information about the dynamics of the atoms in the lattice. We investigate the application of the interferometer for a measurement of $h/m_A$ that together with other well known constants constitutes a measurement of the fine structure constant

Measuring the local gravitational field using survival resonances in a dissipatively driven atom-optics system

We do a proof-of-principle demonstration of an atomic gravimeter based on survival resonances of dissipatively driven atoms. Exposing laser-cooled atoms to a sequence of near-resonant standing-wave light pulses reveals survival resonances when the standing-wave interference pattern accelerates. The resonant accelerations determine the local gravitational acceleration and we achieve a precision of 5 ppm with a drop distance less than 1 mm. The incisiveness of the resonances scales with the square of the drop time. Present results indicate that an appropriately designed atomic gravimeter based on survival resonances might be able to reach a precision of 1μGal with a 10-cm-high fountain. The relatively simple experimental construction of this technique may be of interest for a compact absolute atomic gravimeter

Thermally robust spin correlations between two Rb-85 atoms in an optical microtrap

The complex collisional properties of atoms fundamentally limit investigations into a range of processes in many-atom ensembles. In contrast, the bottom-up assembly of few- and manybody systems from individual atoms offers a controlled approach to isolating and studying such collisional processes. Here, we use optical tweezers to individually assemble pairs of trapped Rb-85 atoms, and study the spin dynamics of the two-body system in a thermal state. The spin-2 atoms show strong pair correlation between magnetic sublevels on timescales exceeding one second, with measured relative number fluctuations 11.9 +/- 0.3 dB below quantum shot noise, limited only by detection efficiency. Spin populations display relaxation dynamics consistent with simulations and theoretical predictions for Rb-85 spin interactions, and contrary to the coherent spin waves witnessed in finite-temperature many-body experiments and zero-temperature two-body experiments. Our experimental approach offers a versatile platform for studying two-body quantum dynamics and may provide a route to thermally robust entanglement generation

Counting atoms in a deep optical microtrap

We demonstrate a method to count small numbers of atoms held in a deep, microscopic optical dipole trap by collecting fluorescence from atoms exposed to a standing wave of light that is blue detuned from resonance. While scattering photons, the atoms are also cooled by a Sisyphus mechanism that results from the spatial variation in light intensity. The use of a small blue detuning limits the losses due to light assisted collisions, thereby making the method suitable for counting several atoms in a microscopic volume

Survival resonances in an atom-optics system driven by temporally and spatially periodic dissipation

We investigate laser-cooled atoms periodically driven by pulsed standing waves of light tuned close to an open atomic transition. This nonunitary system displays survival resonances for certain driving frequencies. The survival resonances emerge as a result of the matter-wave Talbot-Lau effect, similar to the Talbot effect causing quantum resonances in the atom optics δ-kicked rotor. Since the Talbot-Lau effect occurs for incoherent waves, the survival resonances can be observed using thermal atoms. A microlensing effect can enhance the height and incisiveness of the resonances. This may find applications in precision measurements