Intrinsic-Correlation Quantum Key Generation

TL;DR

This paper introduces a quantum key generation scheme using intrinsic quantum correlations of single photons, enhancing security and distance over traditional protocols by encoding key bits directly into correlation functions.

Contribution

The scheme utilizes intrinsic bipartite correlations of single photons and a middle laser source to improve security and doubling the raw key rate compared to existing protocols.

Findings

Robust against intercept-resend attacks due to correlation-based key encoding.

Can estimate information leakage through error analysis.

Doubles communication distance and increases key rate over weak coherent protocols.

Abstract

A new conceptual key generation scheme is presented by using intrinsic quantum correlations of single photons between Alice and Bob. The intrinsic bi-partite correlation functions allow key bit to be generated through high level communication language i.e. a key bit is directly encoded to shared correlation functions not to the state and detection of a photon at Bob does not mean key bit. These make the scheme robust against intercept-resend attack because Alice and Bob can always check the errors in their measurements and reveal the presence of Eve in their channel without leaking any key bit information. The laser source is located in the middle of Alice and Bob, consists of two modes (x,y), relatively random phase-modulated $(\pm \frac{\pi}{2})$ weak coherent states combined in a perfect 50/50 beam splitter. The scheme is strictly relied on the perfect beam splitter and mean photon number less than 1, where more than one photon in a coherent pulse will introduce more errors in Bob even without the presence of Eve. From the percentage of errors in Bob, we can estimate the amount of information will be leaked to Eve in the photon-number splitting attack. This scheme can preserve the randomness of phase-randomized light source for doubling the communication distance as in original Ekert's protocol and providing the raw key generation rate a factor of 2 higher than weak coherent light protocols.