  A detailed theoretical analysis of the spatiotemporal mode of a single photon
prepared via conditional measurements on a photon pair generated in the process
of parametric down-conversion is presented. The maximum efficiency of coupling
the photon into a transform-limited classical optical mode is calculated and
ways for its optimization are determined. An experimentally feasible technique
of generating the optimally matching classical mode is proposed. The theory is
applied to a recent experiment on pulsed homodyne tomography of the
single-photon Fock state (A. I. Lvovsky et al., Phys Rev. Lett. 87, 050402
(2001) - preprint at quant-ph/0101051)
