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Cold Sr Atoms in Optical Lattices for Precision Measurements

Guglielmo M. Tino

I will report on recent results of our experiments based on laser cooled Sr atoms trapped in optical lattices.

We report the realization of a quantum device for force sensing at the micrometric scale. We trapped an ultracold 88Sr atomic cloud with a vertical one-dimensional optical lattice. By observing the Bloch oscillations of atoms in the optical standing wave, we were able to measure the total force on the atoms along the lattice axis, with a spatial resolution of few micrometers. We placed the atomic sample close to a test surface using the same optical lattice as an elevator. We demonstrated precise positioning of the sample at the micrometer scale [1]. We studied coherent delocalization of atomic wave packets in driven lattice potentials also as a mean to improve gravity measurements at small spatial scales [2].

In another experiment, using a magnetically induced spectroscopy scheme, we observed the 0-0 intercombination transition signals in 88Sr with an apparatus based solely on semiconductor laser technology, and demonstrated a method for finding the clock transition that removes the need for extensive frequency metrology hardware. Moreover, the unexpected high contrast in the signal revealed evidence of density dependent collisions in 88Sr atoms [3]. Ongoing work in the frame of ESA SOC project to develop a prototype of a space-compatible Sr clock will be also reported.

[1] F. Sorrentino, A. Alberti, G. Ferrari, V. V. Ivanov, N. Poli, M. Schioppo, and G. M. Tino, Quantum sensor for atom-surface interactions below 10 μm, Phys. Rev. A 79, 013409 (2009)

[2] V.V. Ivanov, A. Alberti, M. Schioppo, G. Ferrari, M. Artoni, M. L. Chiofalo, and G. M. Tino, Coherent Delocalization of AtomicWave Packets in Driven Lattice Potentials, Phys. Rev. Lett. 100, 043602 (2008)

[3] N. Poli, M.G. Tarallo, M. Schioppo, C.W. Oates, G.M. Tino, A simplified optical lattice clock, Appl. Phys. B, in press (2009)

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