QFS 2016 Book of Abstracts

Abstracts

O4.12 Superfluid behavior of quasi-1D parahydrogen inside carbon nanotube Rossi Maurizio(1), Ancilotto Francesco(2) (1) Scuola Normale Superiore di Pisa, Pisa (Italy) (2) Dipartimento di Fisica dell’ Universita’ di Padova, Padova (Italy) We study, by using Quantum Monte Carlo simulations at T=0, para-hydrogen (pH2) confined in carbon nanotubes (CNT) of different radii. The radial density profiles show solid-like concentric shells and eventually a central column, which can be considered an effective 1D fluid whose properties are well described by the Tomonaga-Luttinger theory. For the central column in a (10,10) CNT, we found an ample density range in which the Luttinger liquid is a superfluid stable against a weak disordered external potential, as the one expected in real CNT’s. Our results suggest that pH2 in CNTs could be a practical realization of the long sought-after, elusive superfluid phase of para-hydrogen. P4.1 Nanomechanical Resonators in Superfluid Helium-4 Bradley D. I.(1), Haley R. P.(1), Kafanov S(1), Pashkin Yu. A.(1), Pickett G. R.(1), Poole M.(1), Sarsby M.(1), Tsepelin V.(1), Wilcox T.(1) 1) Department of Physics, Lancaster University, Lancaster, LA1 4YB, UK We have successfully probed the properties of helium-4 using a doubly clamped nanomechanical beam for temperatures from the superfluid transition at 2.2K down to 1.5K at saturated vapour pressure. The beam used was 100nm wide, 100nm thick and 15 μ m long, with a resonance frequency of 8.6MHz and Q-factor of roughly 21000. Observations of resonance frequency shift and damping match well to predictions derived using hydrodynamic contributions from the two fluid model, confirming that the variations seen are due to changes in the fluid properties. The resonances of the beam are observed to be linear at low measurement powers, becoming Duffing-like for measurement powers above 0.1pW.

112