Enhancement of the thermal conductivity of nanotube‑based materials
In this paper, we report the results of analytical and computational
investigation of the heat transfer in carbon nanotube (CNT) ‑ based
materials, such as CNT mats, films, and "buckypaper". The use of a novel
mesoscopic dynamic model allows us to reproduce, for the first time, a
self‑organization of individual CNTs into an interconnected network of
bundles, typical for CNT materials. We find that the values of the thermal
conductivity in the networks of bundles significantly, by almost an order
of magnitude, exceed the values predicted for the random arrangements of
individual nanotubes. This increase is explained by an efficient heat
transfer along the bundles, with each bundle serving as a "highway" for the
thermal transport in the continuous network of bundles. The strong
structural dependence of the thermal transport properties of the CNT
networks explains the large variability of the experimental data reported
for CNT films and mats and points to the feasibility of targeted design of
CNT‑based materials for controlling and directing the heat flow at nano‑
and micro‑scale.
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BPJ1107
Amplifying quantum signal using classical physics
We report a demonstration of significant sensitivity enhancement for a superfluid interferometer by allowing the matter waves to interact with classical resonant features of the experimental apparatus.
When constant pressure and/or temperature differentials are applied across nanoscale apertures separating two reservoirs of superfluid, the fluid within the apertures counterintuitively exhibits oscillation. If we place two such arrays in a torus filled with superfluid, the signal becomes the sum of two oscillations (from two arrays) with an overall amplitude dictated by the phase difference between the two "matter waves." This forms the core of a superfluid-based matter wave interferometer.
In an experiment reported here, we show that we can amplify the interference signal (governed by pure quantum mechanics) by classical means. We adjust the frequency of quantum oscillations to match the classical resonance of the apparatus and harness significant amplification. The capability to employ this type of technique that bridges quantum and classical physics is remarkable and it is rooted in the fact that with ~10^(23) atoms involved in superfluidity, quantum mechanics results in fluid flow that is macroscopic.
With a thirty-fold sensitivity enhancement achieved here, the reported technique makes superfluid-based interferometers great candidates for applications such as geodesy, seismology, inertial navigation etc. as well as a unique tool for fundamental physics.
