Graviton-Photon Oscillations as a Probe of Quantum Gravity

The Gertsenshtein effect could in principle be used to detect a single graviton by firing it through a region filled with a constant magnetic field that enables its conversion to a photon, which can be efficiently detected via standard techniques. The quantization of the gravitational field could then be inferred indirectly. We show that for currently available single-photon detector technology, the Gertsenshtein detector is generically inefficient, meaning that the probability of detection is $\ll 1$. The Gertsenshtein detector can become efficient on astrophysical scales for futuristic single-photon detectors sensitive to frequencies in the Hz to kHz range. It is not clear whether such devices are in principle possible.