  The ability to entangle distant quantum nodes is essential for the
construction of quantum networks and for quantum information processing. For
solid-state quantum emitters used as qubits, it can be achieved by photon
interference. When the emitter is subject to spectral diffusion, this process
can become highly inefficient, impeding the achievement of scalable quantum
technologies. We study two-photon interference in the context of a
Hong-Ou-Mandel (HOM)-type experiment for two separate quantum emitters, with
different detunings with respect to a specific target frequency. We evaluate
the second order coherences that characterize photon indistinguishability
between the two emitters. We find that the two-photon interference operation
that is inefficient in the absence of a control protocol, when the two
detunings are different and spectral overlap is lessened, can be highly
improved by a periodic sequence of $\pi$ pulses at a set target frequency.
Photon indistinguishability in solid state and other quantum emitters subject
to spectral diffusion can thus be enhanced by the proposed pulse sequence and
similar external control protocols despite the fluctuations in the environment.
