  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.
