The fundamental quantum mechanical features forbid non-orthogonal quantum states to be distinguished accurately through a single-shot measurement. Using parity-time ( \(\mathcal{P}\mathcal{T}\) ) quantum mechanics, however, a perfect state discrimination with certainty can be implemented. Here, we experimentally implement quantum state discrimination for photonic single-qubit states by executing post-selected gates and loss-based non-unitary evolutions in the \(\mathcal{P}\mathcal{T}\) -symmetric system, providing a relatively superior strategy for state discrimination in non-Hermitian systems. We also unveil the origin of \(\mathcal{P}\mathcal{T}\) quantum state discrimination by embedding the \(\mathcal{P}\mathcal{T}\) dynamics into a higher-level system under unitary dynamics. This experimental work demonstrates the key principle of \(\mathcal{P}\mathcal{T}\) quantum state discrimination and opens a door of other effective approaches in the \(\mathcal{P}\mathcal{T}\) -symmetric quantum mechanics.
