Fully device-independent quantum key distribution

Umesh V. Vazirani, Thomas Vidick

Quantum cryptography promises levels of security that are impossible to attain in a classical world. Can this security be guaranteed to classical users of a quantum protocol, who may not even trust the quantum devices used to implement the protocol? This central question dates back to the early 1990s when the challenge of achieving Device-Independent Quantum Key Distribution (DIQKD) was first formulated. We answer the challenge by rigorously proving the device-independent security of an entanglement-based protocol building on Ekert's original proposal for quantum key distribution. The proof of security builds on techniques from the classical theory of pseudo-randomness to achieve a new quantitative understanding of the non-local nature of quantum correlations.

Esther Hänggi, Renato Renner, Stefan Wolf

Kumar Nilesh

Eva M. González-Ruiz, Javier Rivera-Dean, Marina F. B. Cenni +3 more

Device-independent quantum key distribution (DIQKD) aims at generating secret keys between distant parties without the parties trusting their devices. We investigate a proposal for performing fully photonic DIQKD, based on single photon sources and heralding measurements at a central station placed between the two parties. We derive conditions to attain non-zero secret-key rates in terms of the photon efficiency, indistinguishability and the second order autocorrelation function of the single-photon sources. Exploiting new results on the security bound of such protocols allows us to reduce the requirements on the physical parameters of the setup. Our analysis shows that in the considered schemes, key rates of several hundreds of secret bits per second are within reach at distances of several tens of kilometers.

Lluís Masanes, Stefano Pironio, Antonio Acín

Hong-Wei Li, Zhen−Qiang Yin, Wei Chen +3 more

In this paper, we propose a quantum key distribution (QKD) protocol based on only a two-dimensional Hilbert space encoding a quantum system and independent devices between the equipment for state preparation and measurement. Our protocol is inspired by the fully device-independent quantum key distribution (FDI-QKD) protocol and the measurement-device-independent quantum key distribution (MDI-QKD) protocol. Our protocol only requires the state to be prepared in the two-dimensional Hilbert space, which weakens the state preparation assumption in the original MDI-QKD protocol. More interestingly, our protocol can overcome the detection loophole problem in the FDI-QKD protocol, which greatly limits the application of FDI-QKD. Hence our protocol can be implemented with practical optical components.