Keywords: low temperature physics

The dripping behavior of superfluid helium-4 has been found to be consistently discretized, even when flow rates vary. This unexpected phenomenon suggests that the superfluid dripping system exhibits time crystallinity by spontaneously breaking continuous time translation symmetry. The condition for the emergence of this continuous time crystal is that the edges of the pendant droplets, which hang from the underside of the cup, can move freely—a characteristic specific to superfluid dripping. This free motion leads to volume-independent oscillation periods for the droplets, effectively eliminating the influence of fluctuations in the flow rates.