  We give a detailed presentation of a recently proposed mechanism of
generating the energy scale of inflation by loop effects in quantum cosmology.
We discuss the quantum origin of the early inflationary Universe from the
no-boundary and tunneling quantum states and present a universal effective
action algorithm for the distribution function of chaotic inflationary
cosmologies in both of these states. The energy scale of inflation is
calculated by finding a sharp probability peak in this distribution function
for a tunneling model driven by the inflaton field with large negative constant
$\xi$ of non-minimal interaction. The sub-Planckian parameters of this peak
(the mean value of the corresponding Hubble constant $H\simeq 10^{-5}m_P$, its
quantum width $\Delta H/H\simeq 10^{-5}$ and the number of inflationary
e-foldings $N\geq 60$) are found to be in good correspondence with the
observational status of inflation theory, provided the coupling constants of
the theory are constrained by a condition which is likely to be enforced by the
(quasi) supersymmetric nature of the sub-Planckian particle physics model.
