N. Poli

Sr Lattice Clock at 1 x 10-16 Fractional Uncertainty by Remote Optical Evaluation with a Ca Clock

Optical atomic clocks promise timekeeping at the highest precision and accuracy, owing to their high operating frequencies. Rigorous evaluations of these clocks require direct comparisons between them. We have realized a high-performance remote comparison of optical clocks over kilometer-scale urban distances, a key step for development, dissemination, and application of these optical standards. Through this remote comparison and a proper design of lattice-confined neutral atoms for clock operation, we evaluate the uncertainty of a strontium (Sr) optical lattice clock at the 1 × 10–16 fractional level, surpassing the current best evaluations of cesium (Cs) primary standards. We also report on the observation of density-dependent effects in the spin-polarized fermionic sample and discuss the current limiting effect of blackbody radiation–induced frequency shifts.

Long-lived bloch oscillations with bosonic Sr atoms and application to gravity measurement at the micrometer scale

We report on the observation of Bloch oscillations on the unprecedented time scale of several seconds. The experiment is carried out with ultracold bosonic 88Sr atoms loaded into a vertical optical standing wave. The negligible atom-atom elastic cross section and zero angular momentum in the ground state makes 88Sr an almost ideal Bose gas, insensitive to typical mechanisms of decoherence due to thermalization and external stray fields. The small size of the system enables precision measurements of forces at micrometer scale. This is a challenge in physics for studies of surfaces, Casimir effects, and searches for deviations from Newtonian gravity predicted by theories beyond the standard model.

Test of Einstein Equivalence Principle for 0-spin and half-integer-spin atoms: Search for spin-gravity coupling effects

We report on a conceptually new test of the equivalence principle performed by measuring the acceleration in Earths gravity field of two isotopes of strontium atoms, namely, the bosonic (88)Sr isotope which has no spin versus the fermionic (87)Sr isotope which has a half-integer spin. The effect of gravity on the two atomic species has been probed by means of a precision differential measurement of the Bloch frequency for the two atomic matter waves in a vertical optical lattice. We obtain the values η=(0.2±1.6)×10(-7) for the Eötvös parameter and k=(0.5±1.1)×10(-7) for the coupling between nuclear spin and gravity. This is the first reported experimental test of the equivalence principle for bosonic and fermionic particles and opens a new way to the search for the predicted spin-gravity coupling effects.

Frequency evaluation of the doubly forbidden 1S0–3P0 transition in bosonic 174Yb

We report an uncertainty evaluation of an optical lattice clock based on the

Precision frequency measurement of visible intercombination lines of strontium

^{1}{S}_{0}\ensuremath{\leftrightarrow}^{3}{P}_{0}

The space optical clocks project: Development of high-performance transportable and breadboard optical clocks and advanced subsystems

transition in the bosonic isotope

Quantum sensor for atom-surface interactions below10μm

^{174}\mathrm{Yb}

Cooling and trapping of ultracold strontium isotopic mixtures

by use of magnetically induced spectroscopy. The absolute frequency of the

A simplified optical lattice clock

^{1}{S}_{0}\ensuremath{\leftrightarrow}^{3}{P}_{0}

Laser Cooling and Trapping of Atomic Strontium for Ultracold Atoms Physics, High-Precision Spectroscopy and Quantum Sensors

transition has been determined through comparisons with optical and microwave standards at NIST. The weighted mean of the evaluations is