Nanoscale Real-Time Detection of Quantum Vortices at Millikelvin Temperatures

TL;DR

This paper demonstrates real-time, nanoscale detection of quantum vortices in superfluid helium at millikelvin temperatures, enabling new insights into quantum turbulence through non-invasive, high-resolution measurements.

Contribution

It introduces a novel nanoscale resonant beam technique for real-time detection of quantum vortices, allowing probing of turbulence at micron scales.

Findings

Successful real-time detection of quantum vortices using a nanoscale resonant beam.

Controlled vortex trapping and release observed via frequency shifts.

Capability to probe turbulence at micron length scales.

Abstract

Since we still lack a theory of classical turbulence, attention has focused on the conceptually simpler turbulence in quantum fluids. Can such systems of identical singly-quantized vortices provide a physically accessible "toy model" of the classical counterpart? That said, we have hitherto lacked detectors capable of the real-time, non-invasive probing of the wide range of length scales involved in quantum turbulence. However, we demonstrate here the real-time detection of quantum vortices by a nanoscale resonant beam in superfluid $^4$He at 10 mK. The basic idea is that we can trap a single vortex along the length of a nanobeam and observe the transitions as a vortex is either trapped or released, which we observe through the shift in the resonant frequency of the beam. With a tuning fork source, we can control the ambient vorticity density and follow its influence on the vortex capture and release rates. But, most important, we show that these devices are capable of probing turbulence on the micron scale.