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Superfluidity and BEC in Nanoporous Media

In this talk I will present our recent research on 4He adsorbed in nanoporous media using path- integral Monte Carlo simulations. Cylindrical nanopore models with and without disorder are considered, with the goal to determine the effective dimensionality of the quantum liquid as a function of the pore diameter and the impact of disorder on both superflow and BEC. The 4He superfluid transition is moved to lower temperatures as the radius of the pore is reduced, in accordance with the experiments. Disorder further supresses the superfluidity. We observe the regime where the tail of the one-body density matrix along the pore axis is flat, characteristic of 3D liquid, as well as the range of temperatures where it decays algebraically, suggesting 2D behaviour. Upon further increase of temperature the tail of the one-body density matrix crosses over to exponential decay characteristic of normal liquid 4He.

Superfuidity; BEC; disorder; porous media; quantum Monte Carlo

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