  A magnetic helix can be wound into a classical Heisenberg chain by fixing one
end while rotating the other one. We show that in quantum Heisenberg chains
\new{of finite length}, the magnetization slips back to the trivial state
beyond a finite turning angle. Avoided level crossings thus undermine classical
topological protection. Yet, for special values of the axial Heisenberg
anisotropy, stable spin helices form again, which are non-locally entangled.
Away from these sweet spots, spin helices can be stabilized dynamically or by
dissipation. For half-integer spin chains of odd length, a spin slippage state
and its Kramers partner define a qubit with a non-trivial Berry connection.
