Superfluidity and BEC of liquid 4He confined in a nanometer-size channel

We have studied the heat capacity and superfluidity of liquid 4He confined in a uniform and straight nanometer-size channel. The heat capacity of liquid 4He in the channel has a bend at a certain temperature TB; below this temperature a small amount of the superfluid fraction appears. This means that 4He atoms enter a BEC-like low-entropy state below TB. Additionally, the superfluid fraction showed a second growth far below TB under low pressure, accompanied by the dissipation. This two-stage growth is possibly a feature of the quasi-one-dimensional system