  Scalable spin-to-photon interfaces require quantum emitters with strong
optical transition dipole moment and low coupling to phonons and stray electric
fields. It is known that particularly for coupling to stray electric fields,
these conditions can be simultaneously satisfied for emitters that show
inversion symmetry. Here, we show that inversion symmetry is not a prerequisite
criterion for a spectrally stable quantum emitter. We find that identical
electron density in ground and excited states can eliminate the coupling to the
stray electric fields. Further, a strong optical transition dipole moment is
achieved in systems with altering sign of the ground and excited wavefunctions.
We use density functional perturbation theory to investigate an optical center
that lacks of inversion symmetry. Our results show that this system close to
ideally satisfies the criteria for an ideal quantum emitter. Our study opens a
novel rationale in seeking promising materials and point defects towards the
realisation of robust spin-to-photon interfaces.
