Figure 3
A comparison of the frequency response of the NEMS oscillators with superconducting NbTi vibrating wires41, 42 and a quartz tuning “space” fork43 operated in the superfluid. (a) The frequency shift as a function of temperature. The lightness and small geometrical sizes of the NEMS resonators give a higher sensitivity to the normal fluid component of the 4He than the other commonly used beam-like devices. (b) Temperature dependence of the reduced Q-factor for various beam-like resonators. The response of the NEMS devices in the liquid is similar to that of the other devices and promises excellent prospects for their use as detectors in quantum fluids. Inset: The temperature dependencies of the Q-factors for all resonators around the superfluid transition. Since the Q-factors are determined by the conventional Stokes′ drag, they are almost independent of temperature above the lambda-point transition T λ = 2.178 K, but begin to increase significantly with the reduction of the temperature below T λ from the reduction in the density of the normal component.
