Extended Data Fig. 6: Angular dependence of quadrupolar interactions.

Trajectories are colour-coded with the time elapsed since the release of the platelets from the laser traps, and the duration of interaction is t_max − t_min ≈ 100 s. The insets are micrographs of platelets repelling each other when the separation vector that points from the centre of one particle to that of the other is roughly parallel or perpendicular to n₀. The images were taken using parallel polarizers shown by the white double arrows. By contrast, the platelets attract when the separation vector is at an angle with respect to n₀, as shown by the trajectory in the middle; the corresponding distance-versus-time dependence is shown in Fig. 4e.