  We analyze through the expectation value of the energy density the spatial
nonlocality of single photons emitted by the spontaneous decay of a Hydrogen
atom. By using a minimal coupling between the quantized electromagnetic field
and the atom, we compute the state of the photon under the assumption that only
a single-photon is produced. The calculations are thus performed in the
subspace of single-photon states which is essentially equivalent to the
rotating wave approximation. We obtain a characterization of the spatial decay
of the energy density. We compute the asymptotic limit of large distances from
the atom at each given time, and find an algebraic behavior of $1/r^6$. This
result confirms that the energy density of single-photon states is nonlocal and
the algebraic decay is far from the maximal quasiexponential localization
predicted by the theory.
