Optical clocks ultimate limit in stability is given by the so-called Quantum Projection Noise. This limitation can be reduced in optical lattice clocks by increasing the number of atoms trapped in the lattice. Further, in optical clock measurements, highest precision requires a probing laser with very narrow linewidth and a stable frequency, to prevent additive noise. Scientists at the joint institute of the University of Colorado Boulder and the National Institute of Standards and Technology (JILA/NIST), in a collaboration with the National Metrology Institute of Germany (PTB, Germany), and the Max Planck Institute of Quantum Optics (MPQ, Germany), have demonstrated a stability of 4.8 x 10^-17 at one second measuring time for two independent strontium optical clocks, mastered by the team of Professor Jun Ye. Essential for this breakthrough is our Ultra-Low Noise Optical Frequency Comb technology.

The FC1500-ULN^plus serves as a clockwork to transfer the cryogenic silicon cavity-stabilized laser purity to the laser responsible to perform the clock transition spectroscopy on the strontium atoms. Within an averaging time of one hour, the stability of the clocks reaches the mid-10^-19 level, setting a precision-record for an optical atomic clock. This result has far-reaching consequences for quantum physics, opening new prospects in quantum sensing for exploring new physics and opening the path towards the hunt of Dark Matter. Eventually, this new class of optical standards will also permit the redefinition of the International Time Scale, featuring an optical timekeeping.

The publication: Oelker et al., Demonstration of 4.8 x 10^-17 stability at 1 s for two independent optical clocks,  Nature Photonics 13, 714-719 (2019).

More on: Derevianko, A., Accurate and stable timekeeping, Nature Reviews Physics 1, 478–479 (2019)