Any superfluid can theoretically act as a quantum solvent, however in practice the only viable superfluid medium that can currently be used is helium-4, and it has been successfully accomplished in controlled conditions.
Any superfluid can theoretically act as a quantum solvent, ie: any quantum liquid is capable of solvating other chemical species. In practice however, the only viable superfluid medium that can currently be used is helium-4, and it has been successfully accomplished in controlled conditions.