Localization and Tunability of ⁴He Inside Pre-plated Nanopores

Low dimensional quantum fluids, where one can probe the effects of enhanced thermal and quantum fluctuations on macroscopic quantum wavefunctions, can be experimentally realized through transverse confinement of superfluid helium on scales smaller than the coherence length. Reaching this scale is difficult, requiring physical confinement in single or multiple pores with nanometer radii. Porous silicates such as MCM-41 have a pore radius larger than the coherence length of ⁴He, and in this work we systematically explore the possibility of pre-plating pores with other elements to reduce the pore size without localizing the confined superfluid. Through a direct solution of the few-body Schrodinger equation combined with quantum Monte Carlo, we explore a wide range of pre-plating elements, including rare gases and alkali metals. For rare gases, we find that the density of a helium core inside the pore is nearly constant, but a Cs coating prevents localization near the walls and presents a platform to realize a tunable one-dimensional quantum liquid.