Fig. 4: Comparison of spectral lineshapes between transversely cold and hot anti-atoms within the same series in the cooling experiment.

a, Comparison of the spectral lineshapes between equally sized subsamples of the ‘stack and cool’ series data. The lineshape for the subsample with the transverse energy greater (smaller) than its median value is shown with a solid line (dashed line filled under the curve). b–h, Analogous comparisons are given for the cooling (b), no-laser (c) and heating (d) series, and the corresponding simulations (e–h). The error bars represent 1 s.d. counting statistics. In all cases, the curves are drawn to guide the eye. These correlations indicate that in the laser-cooling series (a, b), transversely colder atoms are also longitudinally colder, while the correlation is reversed for the heating series (d). See text and Methods.