Fully suspended nano-beams for quantum fluids

Abstract

Non-invasive probes are keystones of fundamental research. Their size, and maneuverability (in terms of e.g. speed, dissipated power) define their applicability range for a specific use. As such, solid state physics possesses e.g. Atomic Force Microscopy (AFM), Scanning Tunneling Microscopy (STM), or Scanning SQUID Microscopy. In comparison, quantum fluids (superfluid ${}^3$He, ${}^4$He) are still lacking probes able to sense them (in a fully controllable manner) down to their smallest relevant lengthscales, namely the coherence length ${\xi }_0$. In this work we report on the fabrication and cryogenic characterization of fully suspended (hanging over an open window, with no substrate underneath) Si${}_3$N${}_4$ nano-beams, of width down to 50 nm and quality factor up to $10^5$. As a benchmark experiment we used them to investigate the Knudsen boundary layer of a rarefied gas: ${}^4$He at very low pressures. The absence of the rarefaction effect due to the nearby chip surface discussed in Gazizulin et al. [1] is attested, while we report on the effect of the probe size itself.

References in corpus (16)

• Topological Superconductivity and Superfluidity
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• Generalized Knudsen Number for Unsteady Fluid Flow
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• Probing superfluid ${}^4\mathrm{He}$ with high-frequency nanomechanical resonators down to $\mathrm{mK}$ temperatures
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• Probing Bogoliubov quasiparticles in superfluid ${}^3$He with a 'vibrating-wire like' MEMS device
• Detecting the "phonon wind" in superfluid ${}^4\mathrm{He}$ by a nanomechanical resonator
• Surface-induced near-field scaling in the Knudsen layer of a rarefied gas
• On the Transition from Potential Flow to Turbulence Around a Microsphere Oscillating in Superfluid ^4He
• Multimode probing of superfluid ${}^4\mathbf{He}$ by tuning forks

Cited by in corpus (1)

• Nano-beam clamping revisited