Anomalous suppression of superfluidity in⁴he confined in a nanoporous glass

The superfluidity of ⁴He confined in a porous glass at a pressure up to 5 MPa is discussed. The increasing pressure supressed the superfluidity and the superfluid transition temperature approaches 0 K at critical pressure of approximately 3.4 Mpa. The extreme confinement of ⁴He in to the nanopores induces a quantum phase transition from a superfluid to a nonsuperfluid at 0 K and at P_c. The results show a strong supression of ₄He superfluidity by extreme confinement in to the nanopores.