Spinners on an air table as an inertial chiral fluid

Conventionally, studies of active matter are concerned with overdamped objects. Recently, researchers have gradually picked up interest in the less studied underdamped active matter and have found interesting effects caused by the delay of speed gain, such as the mitigated phase separation. Previous experimental studies on inertial active matter have tried to increase the mass of the driven objects to increase the inertia. On the contrary, in our study, we increase the inertia by significantly decreasing the damping. To do so, we float rotationally-driven disks (spinners) on an air table. Each spinner is an acrylic disk with 6 cm in diameter and is powered by two blowers blowing in opposite directions at the ends of a diameter. The damping is so small that a spinner takes a few seconds to reach the terminal angular speed from zero. Gears are added to the rims of the spinners to promote the conversion between translational and rotational energy upon collisions. The difference between collisions of the same-handedness and opposite-handedness spinner pairs creates different emergent spin rate distributions and spatial currents depending on the ratio between the left-handed and right-handed spinners.