# Quantum Physics Seminar - Cyrille Solaro: A Trapped Atom Interferometer to Search for New Forces

### Time

Thursday 14 April 2016,  at 10:15 - 11:00

Quantum Physics Seminar

Speaker:  Cyrille Solaro, SYRTE, Observatoire de Paris, France

Title:  A Trapped Atom Interferometer to Search for New Forces.

Abstract:

We demonstrate a trapped atom interferometer of Rb87 in a vertical optical lattice. For shallow depths of the lattice, stimulated Raman transitions can be used to induce coherent transport between adjacent Wannier-Stark states, allowing us to perform atom interferometry and to measure with very high sensitivity, shifts in the Bloch frequency. A careful control of the trapping potential and a symmetrized interferometer configuration lead to a local force sensor with a state-of-the art relative sensitivity on the Bloch frequency, and thus on the gravity acceleration, of 1.8 10^{-6} at 1s.

We recently installed a crossed dipole trap in order to increase the number of atoms per well from a few to up to about one thousand thanks to evaporative cooling. Working with much denser atomic cloud allowed reducing coupling and phase inhomogeneities in the interferometer and increasing the coherence time by a factor 4. At densities of a few 10$^{12}$cm$^{-3}$, we observe counterintuitive behavior of the symmetrized interferometer configuration. We understand this phenomenon as a subtle competition between the widely used spin-echo technique and a very general mechanism based on identical rotation effect (ISRE). In trapped atomic clocks, ISRE, originating from particle indistinguishability, can enhance the clock's coherence via the so-called spin self-rephasing mechanism, up to several tens of seconds! We propose a model that reproduces well the experimental data and offers clear insight into this remarkable interplay between spin-echo and spin self-rephasing.

Coffee/tea and bread rolls will be served at 10:05