Final answer:
Device-independent testing is not directly applicable to test quantum discord, An open question remains regarding the applicability of device-independent testing to quantum discord.
Step-by-step explanation:
Device-independent testing is a powerful technique used to characterize quantum resources without relying on trust in the measurement devices. While device-independent tests can be used to verify non-local correlations like entanglement, they are not directly applicable to test quantum discord.
Quantum discord is a measure of quantum correlations that is based on the discrepancy between classical and quantum versions of a joint measurement. Since device-independent testing focuses on non-local correlations, which can be tested without detailed knowledge of the devices used, it does not directly address the concept of quantum discord.
While device-independent testing is an active area of research in quantum information, the applicability of this technique to specifically test quantum discord has not been extensively explored. Therefore, it remains an open question whether quantum discord can be fully captured by device-independent testing.