On the Bose-Einstein Condensation of Rotons

TL;DR

This paper revisits the possibility of Bose-Einstein condensation of rotons in helium, suggesting it can occur at lower velocities than previously thought if the temperature is sufficiently low.

Contribution

It proposes that roton condensation can happen at velocities below the Landau critical velocity when the temperature is sufficiently reduced.

Findings

Roton condensation is possible at velocities below the Landau critical velocity.

Lower temperatures facilitate the Bose-Einstein condensation of rotons.

The critical velocity for condensation decreases with temperature.

Abstract

Bose-Einstein condensation of rotons in helium was considered long ago. It was shown that the relative velocity of the normal motion in this state must be equal to the Landau critical velocity. We argue that the condensation can be attained at a smaller velocity if the temperature is low enough.