Good question.
Currently, Orch OR (Orchestrated Objective Reduction), proposed by Roger Penrose and Stuart Hameroff, stands as one of the most prominent scientific theories of consciousness.
Available evidence for its core claims includes indirect supportive findings, such as coherent quantum vibrations, superradiance, and exciton migration in microtubules at physiological temperatures, along with selective disruption by anesthetics that correlates with loss of consciousness. There are also some behavioral correlations (e.g., microtubule stabilization delaying anesthesia onset in rats). However, it still lacks any direct demonstration that quantum gravity-induced objective reductions (OR) produce subjective qualia.
This unfortunately means we lack a conclusive way to prove or disprove subjective experience even in humans, let alone in artificial systems.