The only thing I can imagine an work in theory, is by exploiting the mixing of gravitons and photons in an external electromagnetic field, see here. You then produce ordinary laser light and this gets partially converted to coherent gravitational radiation. This is analogous to the Primakoff effect where photons could be converted to hypothetical axions in an external field. So-called "light shining through walls experiments" are being performed, where experimentalists let laserlight move through a strong magnetic field, shine that onto a wall, and then attempt to detect axions on the other side of the wall by applying a strong magnetic field which would convert the axions back to photons. One then exploits the fact that these photons would be in precise coherence with the laserlight on the other side of the wall to set strong limits on the properties of axions.

The only thing I can imagine can work in theory, is by exploiting the mixing of gravitons and photons in an external electromagnetic field, see here. You then produce ordinary laser light and this gets partially converted to coherent gravitational radiation. This is analogous to the Primakoff effect where photons could be converted to hypothetical axions in an external field. So-called "light shining through walls experiments" are being performed, where experimentalists let laserlight move through a strong magnetic field, shine that onto a wall, and then attempt to detect axions on the other side of the wall by applying a strong magnetic field which would convert the axions back to photons. One then exploits the fact that these photons would be in precise coherence with the laserlight on the other side of the wall to set strong limits on the properties of axions.