Brillouin Spectroscopy of Metastable Superfluid Helium-4

We report measurements of the Brillouin frequencies of acoustically driven metastable states of superfluid He-4 at T similar to 1 K. This is done using a stimulated Brillouin gain spectrometer operating on a confined spatiotemporal domain (similar to 40 mu m, 200 ns). Our work questions previous experimental results regarding the metastable states of liquid He-4 and suggests that thermal effects or vortices can play a significant role in the cavitation process. Thanks to our time-resolved measurements, we also find that it is possible to probe metastable superfluid He-4 beyond the commonly defined cavitation threshold.

Automated summary

We measured the Brillouin frequencies of acoustically driven metastable states of superfluid He-4 at T similar to 1 K and found that thermal effects or vortices can play a significant role in the cavitation process.