Intrinsic Quantum Correlations of Weak Coherent States for Quantum Communication

TL;DR

This paper demonstrates a novel detection scheme revealing intrinsic quantum correlations in weak coherent states, enhancing security in quantum key distribution over 10 km fiber links.

Contribution

Introduces a new detection method to observe quantum correlations in weak coherent states, supplementing existing QKD protocols with potential for increased security.

Findings

Successfully generated bipartite correlations using homodyne detection.

Demonstrated secure correlations over 10 km fiber transmission.

Proposed scheme adds a physical security layer to QKD protocols.

Abstract

Intrinsic quantum correlations of weak coherent states are observed between two parties through a novel detection scheme, which can be used as a supplement to the existence decoy-state BB84 and differential phase-shift quantum key distribution (DPS-QKD) protocols. In a proof-of-principle experiment, we generate bi-partite correlations of weak coherent states using weak local oscillator fields in two spatially separated balanced homodyne detections. We employ nonlinearity of post-measurement method to obtain the bi-partite correlations from two single-field interferences at individual homodyne measurement. This scheme is then used to demonstrate bits correlations between two parties over a distance of 10 km through a transmission fiber. We believe that the scheme can add another physical layer of security to these protocols for quantum key distribution.