  The frequency comb of a multimode interferometer offers exceptional
scalability potential for field-encoded quantum information. However, the
staple field detection method, homodyne detection, cannot access quantum
information in the whole comb because some spectral quadratures (and their
asymmetries with respect to the LO) are out of reach. We present here the first
general approach to make arbitrary, one-shot measurements of a multimode
quantum optical source, something that is required for photonic quantum
computing and is not possible when using homodyne detection with a pulse-shaped
LO. This approach uses spectral mode-matching, which can be understood as
interferometry with a memory effect. We derive a complete formalism and propose
an implementation by microcavity arrays.
