Zero- and one-dimensional 4He Bose fluids realized in nanometer pores Original Research Article

To realize helium quantum fluids in clusters and in one-dimensions, we have studied 4He and 3He adsorbed in nanometer diameter pores of zeolite and FSM-16. In each cage 13 Å in diameter of Na-Y zeolite covered with helium solid layer, a few helium atoms are suggested to be Bose and Fermi clusters for 4He and 3He atoms, respectively, of which symmetry difference results in completely different eigenstates and low temperature heat capacities. In the one-dimensional (1D) pores of 18 and 28 Å in FSM-16, 4He fluid nanotubes are formed on the pore walls preplated with solid-like helium layers. Absolute 1D Bose fluid is realized at sufficiently low temperatures and appropriate coverages, where the transverse motion in the fluid tube is in a ground state. We observed a temperature-linear term of the heat capacity probably due to the 1D phonon heat capacity of the 1D interacting Bose fluids.