How gravitational waves change photon orbital angular momentum quantum states

We explore the evolution of vortex light in the presence of gravitational waves (GWs) and demonstrate that the quantized orbital angular momentum (OAM) states can make transitions to other states due to the GWs. The interaction is calculated based on the framework of the wave propagation in linearized gravity theory and canonical quantization of the light field in curved spacetime. It is found that when a photon possessing OAM of $l$ interacts with GWs, the OAM modes of $l\pm1$ and $l\pm2$ may be excited with probabilities of $P_{l\pm1}\sim 10^{-17}$ and $P_{l\pm2}\sim 10^{-20}$, respectively. Higher probabilities of the transitions can be achieved when the photon radial wave vector or the propagation distance is increased, or when the photons encounter GWs with stronger amplitudes or smaller frequencies. Thus, a new GW detection technique is proposed, which may exhibit good performance in a wide range of GW frequencies. Furthermore, the detector is insensitive to seismic noise and is more advantageous for determining the distance of the source compared to current interferometer detectors.