Enhancing Minimum-Consumption Discrimination of Two-Qubit Quantum States via Entangling Measurements (Invited)

Reducing the average number of copies consumed in quantum state discrimination under a given error rate is referred to as minimum-consumption quantum state discrimination. Minimum-consumption quantum state discrimination allows the saved resources to be utilized for subsequent quantum tasks, and it holds significant practical value in tasks such as quantum cryptography. In this paper, we investigate minimum-consumption quantum state discrimination of two-qubit quantum states. The theoretical results indicate that even when two-qubit quantum states only possess classical correlations and no quantum entanglement, entangled measurements still far outperform the effects of performing local measurements on the two qubits individually. Experimental results confirm that when the error rate requirement is low enough, the average number of copies consumed by entangled measurement device is only one-twelfth of that consumed by local measurements, while still meeting the error rate requirement. Our research results highlight the role of entangled measurements in minimum-consuption quantum state discrimination, demonstrating the importance of entanglement in quantum measurements.