A Fifth-Coordinate Gravimeter: Absolute Gravity Measurement by Extra-Coordinate Phase Readout

Absolute gravimeters measure the local gravitational acceleration by timing a falling mass or, in atom-interferometric form, by reading the phase accumulated by falling atoms. This paper specifies a gravimeter that reads the same acceleration through the extra-coordinate phase channel, in which the scale factor is set by the product of the optical wavevector, a stated fifth-coordinate coupling of five per cent, and the square of the interrogation time. The computed scale factor is 5.031e+04 radians per unit acceleration; the single-shot acceleration noise is 6.76e-08 metres per second squared; and the sensitivity is 8.3 microgal per root hertz, reaching a tenth of a microgal in 1.9 hours of averaging. The total phase at standard gravity is 4.93e+05 radians, counted by fringe tracking from a cold start procedure described in the design. SIMULATED, NOT MEASURED: the figures are computed from stated assumptions.