  The paper studies the properties of an oscillator whose Hamiltonian is
$[(1+q^2)(1+p^2)]^{1/2}-1$. It can be deduced from the nonlinear theory of
electrodynamics originally proposed by Max Born in 1934. The quantization of
such oscillator represents a possible regularization of the Barry and Keating's
Hamiltonian, which has been proposed in the framework of the theory of
non-trivial zeros of the Riemann's $\zeta$ function.
