Fig. 2: Experimental data.
Measured acceleration as a function of the source mass temperature T s. A quartic dependence on T s is observed for the acceleration experienced by caesium atoms towards the source mass. a, Data from 63 thermal cycles, about 2–5 h each, are binned in temperature with N bin = 65 measurements per bin. The black dots represent the weighted mean of each bin. Vertical error bars show the 1-sigma statistical uncertainty on the weighted mean. Systematic effects have been considered in detail and show no significant contributions to the error bars; see the Methods section. Horizontal bars show the temperature spread of the N bin measurements in the bin. The red dotted line presents a calculation of the average acceleration imparted to the atoms during interferometry. The error for this theoretical prediction is dominated by the approximately 10% uncertainty of the source mass emissivity. The gravitational pull of the cylinder gives the room-temperature offset of the acceleration, indicated by the black dotted line at a grav = −66 nm s−2. b, Residuals from the bulk acceleration data (cyan) to the zero-parameter theory model. c, A histogram of the bulk residuals is well described by a normal distribution. A Gaussian fit to the histogram (black dot–dashed curve) has mean compatible with zero within the standard error of 29 nm s−2.
