A high-performance optical lattice clock based on bosonic atoms

Optical lattice clocks with uncertainty and instability in the 10􀀀17-range and below have so far
been demonstrated exclusively using fermions. Here, we demonstrate a bosonic optical lattice clock
with 3 10􀀀18 instability and 2:0 10􀀀17 accuracy, both values improving on previous work by a
factor 30. This was enabled by probing the clock transition with an ultra-long interrogation time of
4 s, using the long coherence time provided by a cryogenic silicon resonator, by careful stabilization
of relevant operating parameters, and by operating at low atom density. This work demonstrates
that bosonic clocks, in combination with highly coherent interrogation lasers, are suitable for highaccuracy
applications with particular requirements, such as high reliability, transportability, operation
in space, or suitability for particular fundamental physics topics. As an example, we determine
the 88Sr { 87Sr isotope shift with 12 mHz uncertainty.