A Network of Optical Lattice Clocks for Ultralight Dark Matter and Relativistic Geodesy: Coupling Reach Computed from Clock Instability

Twelve optical lattice clocks, each with fractional instability 1e-16 per root second averaging to a 3e-19 floor, are designed as a correlated network. The 66 pairwise comparisons suppress uncorrelated clock noise, giving a detectable oscillating fractional-frequency amplitude of 3.69e-20 for an ultralight scalar field of mass 1e-17 eV over its 4.14e+08 second coherence time, corresponding under the stated field model to a coupling reach of order 3.6e-07. The same comparisons resolve gravitational-potential differences equivalent to 0.3 cm of height. The network totals 260 tonnes and 336 kW. All figures are computed from the stated instability model; the design is simulated, not measured.