Anomalous suppression of superfluidity in 4He confined in a nonporous glass -: art. no. 075302

We explore the superfluidity of He-4 confined in a porous glass, which has nanopores of 2.5 nm in diameter, at pressures up to 5 MPa. With increasing pressure, the superfluidity is drastically suppressed, and the superfluid transition temperature approaches 0 K at some critical pressure, P(c)similar to3.4 MPa. The feature suggests that the extreme confinement of He-4 into the nanopores induces a quantum phase transition from a superfluid to a nonsuperfluid at 0 K and at P-c.