Potential Profiling With Clocks Between Surface and Deep Underground Laboratories

Underground laboratories offer a controlled vertical baseline that surface geodesy rarely provides: a known depth, a stable environment and, in several cases, existing fibre. A clock taken underground measures a potential difference that is large compared with modern clock uncertainty. This paper computes the signal for five depths, expresses the signal-to-noise ratio against a stated clock uncertainty, and discusses what such a profile can calibrate: not new gravity physics, but the practical chain of transport, link and environmental corrections used in surface campaigns. The computed results, taken from the deposited script, are as follows in summary: The computed rows entry 1 depth_m is 250. The computed rows entry 1 frac is 2.73e-14. The computed rows entry 1 height_equiv_m is 250. The computed rows entry 1 snr_vs_1e18 is 2.73e+04. The computed rows entry 2 depth_m is 500. The computed rows entry 2 frac is 5.46e-14. The computed rows entry 2 height_equiv_m is 500. The computed rows entry 2 snr_vs_1e18 is 5.46e+04. The computed rows entry 3 depth_m is 1000. The computed rows entry 3 frac is 1.09e-13. The computed rows entry 3 height_equiv_m is 1000. The computed rows entry 3 snr_vs_1e18 is 1.09e+05. The computed rows entry 4 depth_m is 1400. The computed rows entry 4 frac is 1.53e-13. The study is a computation from stated assumptions, not a measurement, and its figures should be read at the precision those assumptions support.