Frequency comparison of optical lattice clocks

摘要

We demonstrate the frequency comparison of two optical lattice clocks at the relative stabilities close to the quantum projection noise (QPN) limit of optical lattice clocks. This stable frequency comparison is accomplished by synchronous interrogations of two clocks by a common probe laser, which allows us to cancel out the probe laser's frequency noise. We perform the frequency comparison of a one-dimensional (ID) optical lattice clock with spin-polarized fermions ~(87)Sr and a three-dimensional (3D) optical lattice clock with unity-occupation bosons ~(88)Sr and achieve the Allan standard deviation of σ_y(τ)=4 × 10~(-16) τ~(-1/2), which corresponds to the QPN limited stability for N=1,000 atoms and the spectrum linewidth 7=8 Hz. The relative stability reaches 1 × 10~(17) with an averaging time of 1,600 s. Finally, we discuss the prospects to realize 10~(-18) fractional inaccuracies and the possible application of frequency comparison with synchronous interrogations to remote clocks' comparison for relativistic geodesy.