Superfluid transition of 4He confined in porous glasses

Recent results of superfluid density and heat capacity measurements of 4He confined in porous Vycor and aerogel glasses of very high porosity are reviewed. These measurements support the interpretation that the superfluid transition of 4He confined in Vycor belongs to the same universality class as that of bulk 4He. The superfluid density of 4He in aerogol glass can be described by a simple power law to a reduced temperature of 10-4 K; however, the resultant critical exponent and heat capacity behavior are found to be distinctly different from that of bulk. (orig.)