  Solid-state single-photon emitters are attractive for realization of
integrated quantum systems due to their experimental convenience and
scalability. Unfortunately, however, their complex mesoscopic environments
cause photons from different emitters to be spectrally distinguishable. Here we
demonstrate spectral alignment of two solid-state single-photon emitters by
utilizing the strain gradient. Multiple germanium vacancy (GeV) color centers
in diamond are created in fabricated diamond microcantilevers using focused ion
beam implantation. The strain response of the electronic energy levels of the
GeV is measured by inducing an electrically controlled strain in the device.
Leveraging the large strain gradient, we tune two GeVs in the spot to emit at
the same optical wavelength. Simultaneous resonant excitation of two spectrally
aligned GeVs is demonstrated using a narrow linewidth laser. This strain
gradient tuning can be used to realize spectrally identical quantum emitters
for on-chip integrated quantum systems.
