Sr optical lattice clock

The Sr optical clock is the most widespread optical frequency standard around the world, the most stable and the most accurate. Its clock frequency has shown a reproducibility of uncertainty at the level of 10−17. Frequency comparisons of Sr clocks have been already used to constrain gravitational theories and are foreseen to be used in relativistic geodesy. This is because of the relative ease to produce the necessary laser sources for laser-cooling its atoms down to microkelvin temperatures, and to probe the 1S03P0 clock transition at 698 nm. Following the pioneering experiments at Jila by Jan Hall (now Jun Ye) and at University of Tokyo by H. Katori, INRiM is now assembling its own Sr optical lattice clock. After almost two decades of development, the Sr optical standard at INRiM will present some original solutions to have both an ultra-stable and accurate apparatus. In particular, it will employ a 2D-MOT loaded atomic beam which ensures suppression of BBR shift from the atomic oven and an optical shutter of the Sr beam to suppress background collision shifts.

Furthermore, INRiM will design and develop within the European projects Q-Clocks (QuantERA) and USOQS (EMPIR 2017) a cavity-enhanced probing scheme to surpass the quantum projection noise limit and explore quantum-enhancement in optical clocks. We will also pursue new methods for cavity frequency stabilization and ultra-narrow diode laser for second harmonic generation of the clock light.

Sr Clock funded projects


  • Marco G. Tarallo, leader maximo

  • Matteo Barbiero, fido scudiero / QKD Scientific coordinator

  • Juan Pablo Salvatierra, apprendista stregone


Journal articles

  1. Optically loaded Strontium lattice clock with a single multi-wavelength reference cavity
    M Barbiero, D Calonico, F Levi, MG Tarallo, IEEE Transactions on Instrumentation and Measurement, vol. 71, pp. 1-9, 2022, Art no. 1501509 (2022)

  2. Sideband-Enhanced Cold Atomic Source for Optical Clocks
    M Barbiero, MG Tarallo, D Calonico, F Levi, G Lamporesi, G Ferrari, Physical Review Applied 13 (1), 014013 (2020)

Conference proceedings

  1. INRIM Sr Optical Clock: An Optically Loaded Apparatus for High-Stability Metrology
    M Barbiero, MG Tarallo, F Rullo, M Risaro, C Clivati, D Calonico, F Levi
    , 2021 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS), 2021, pp. 1-3, doi: 10.1109/EFTF/IFCS52194.2021.9604341

  2. Toward a quantum-enhanced strontium optical lattice clock at INRIM
    MG Tarallo, EPJ Web of Conferences 230, 00011, arXiv preprint arXiv:2006.10405, 2020

  3. A strontium optical lattice clock apparatus for precise frequency metrology and beyond
    MG Tarallo, D Calonico, F Levi, M Barbiero, G Lamporesi, G Ferrari, 2017 Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS), 2017, pp. 748-750, doi: 10.1109/FCS.2017.8089020.


  • Optical frequency stabilization to a doubly forbidden atomic transition for a strontiumoptical lattice clock
    J. P. Salvatierra, University of Turin
    M.Sc. Dissertation in Physics of Advanced Technologies, 2022

  • Theoretical modeling and simulation of the generation of spin-squeezed states for quantum enhanced atomic clocks
    A. Caprotti, University of Milan
    M.Sc. Dissertation in Physics, 2022

  • Laser Cooling and Trapping of Strontium for an Optical Lattice Clock
    F. Rullo, University of Turin
    M.Sc. Dissertation in Physics of Advanced Technologies, 2021

  • Tecniche di Imaging per la Diagnostica di Atomi di Stronzio Ultrafreddi
    D. Racca, University of Turin
    B.Sc. Dissertation in Physics, 2019

  • Novel techniques for a Strontium Optical Lattice Clock
    M. Barbiero, Politecnico Turin
    Ph.D Thesis in Metrology, 2019

Theses and positions available!

Contact us: m.tarallo[at]