  The analysis of nonclassical rotational response of superfluids and
superconductors was performed by Onsager (in 1949) \cite{Onsager} and London
(in 1950) \cite{London} and crucially advanced by Feynman (in 1955)
\cite{Feynman}. It was established that, in thermodynamic limit, neutral
superfluids rotate by forming---without any threshold---a vortex lattice. In
contrast, the rotation of superconductors at angular frequency ${\bf
\Omega}$---supported by uniform magnetic field ${\bf B}_L\propto {\bf \Omega}$
due to surface currents---is of the rigid-body type (London Law). Here we show
that, neglecting the centrifugal effects, the behavior of a rotating
superconductor is identical to that of a superconductor placed in a uniform
fictitious external magnetic filed $\tilde{\bf H}=- {\bf B}_L$. In particular,
the isomorphism immediately implies the existence of two critical rotational
frequencies in type-2 superconductors.
