Recent proposals are emerging for the experimental detection of entanglement mediated by classical gravity, carrying significant theoretical and observational implications. In fact, the detection of gravitational waves (GWs) in LIGO provides an alternative laboratory for testing various gravity-related properties. By employing LIGO's arms as oscillators interacting with gravitational waves (GWs), our study demonstrates the potential for generating quantum entanglement between two mutually orthogonal modes of simple harmonic oscillators. Our findings reveal unique entanglement dynamics, including periodic ``collapse and revival" influenced by GW oscillations, alongside a distinct ``quantum memory effect." We believe that these forecasts may hold significance for both theoretically probing and experimentally verifying the quantumness of gravitational waves.