Fig. 5

Force measurements close to the thermal limit. a Histogram of positional fluctuations of a magnetic bead around its field-dependent steady-state position. The reported value corresponds to the standard deviation of the Gaussian fit. b Harmonic potential fitted through the data in Fig. 4e and extrapolated across the stagnation point. The actual measured experimental data are shown in red, while mirrored data are marked in grey. The measured fluctuation in a amounts to ca. 3 times the thermal energy at room temperature