Ultrastable optical frequency transfer over deployed multicore fiber for optical clock comparison and synchronization

In this talk, I will present the first demonstration of ultrastable optical frequency transfer over deployed multicore fiber. We have achieved fractional frequency instability better than 3×10-19 over 25.2 km of deployed multicore fiber. This result shows that multicore fibers can support the transfer of world’s best optical clocks and opens the door for optical clock comparisons over long-haul optical fibers.