Unconditionally secure device-independent quantum key distribution with only two devices
This work addresses a key scalability issue in DIQKD for secure communication, though it is incremental as it builds on existing security frameworks with a focus on reducing device requirements.
The paper tackles the practical limitation in device-independent quantum key distribution (DIQKD) of requiring separate isolated devices for each entangled pair by introducing a protocol that requires only one device per user, achieving unconditional security against an adversarial supplier under local signaling constraints.
Device-independent quantum key distribution is the task of using uncharacterized quantum devices to establish a shared key between two users. If a protocol is secure regardless of the device behaviour, it can be used to generate a shared key even if the supplier of the devices is malicious. To date, all device-independent quantum key distribution protocols that are known to be secure require separate isolated devices for each entangled pair, which is a significant practical limitation. We introduce a protocol that requires Alice and Bob to have only one device each. Although inefficient, our protocol is unconditionally secure against an adversarial supplier limited only by locally enforced signalling constraints.