  In this paper, we will give a short review on \textit{quantum spring}, which
is a Casimir effect from the helix boundary condition that proposed in our
earlier works. The Casimir force parallel to the axis of the helix behaves very
much like the force on a spring that obeys the Hooke's law when the ratio $r$
of the pitch to the circumference of the helix is small, but in this case, the
force comes from a quantum effect, so we would like to call it \textit{quantum
spring}. On the other hand, the force perpendicular to the axis decreases
monotonically with the increasing of the ratio $r$. Both forces are attractive
and their behaviors are the same in two and three dimensions.
