Chasing signs of the Kelvin-wave cascade on a single vortex using nanoscale mechanical resonators*

It is believed that Kelvin waves propagating on a quantum vortex provide a fundamental channel of dissipation of superfluid turbulence, driven by the Kelvin-wave cascade. In spite of decades of theoretical work, no conclusive experimental evidence on the existence of such cascade has been presented. In our experiments we use nanoscale mechanical resonators operating at about 1MHz, immersed in superfluid ⁴He [1]. These probes are sensitive enough to probe single vortices. A vortex can be attached to the resonator by creating turbulence using a nearby tuning fork. This allows measuring the restoring force and the dissipation the vortex imposes on the resonator as a function of time, until the vortex is disconnected. We compare the observations with the theoretical expectation [2], and discuss possible future experiments.

[1] PRB 100, 020506(R) (2019) [2] PRB 84, 064516 (2011)