Keywords: Superfluid
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Superfluid dripping: a new analog for continuous time crystals
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.
Shota Takamatsu, Ryota Yamane, Tomoyuki Tani, Yuri Ishimoto, Keito Miyake, Yuki Aoki, and Ryuji Nomura
Lack of Oscillatory Motion of Superfluid ⁴He During its Dripping from a Needle
Although pendant droplets commonly exist in our daily lives, their dynamics are not fully understood. To obtain further understanding of its physics, we observed superfluid helium dripping from a thin needle by a high-speed camera. Superfluidity is an inviscid liquid state only happening in helium at low temperatures. The present study where we used a thin needle to eliminate the droplet’s remnant volume clearly demonstrated that the dissipation-less large oscillation observed in the previous experiments was crucial for the discretization of the dripping period which is novel phenomenon reflecting the anomalous fluid properties of superfluid helium.
Tomoyuki Tani, Keigo Sawada, Keito Miyake, Shota Takamatsu, Ryota Yamane, Yuri Ishimoto, Ryuta Matsukawa, Yuki Aoki, and Ryuji Nomura