Entanglement-Enhanced Quantum Key Distribution

TL;DR

This paper introduces a quantum key distribution protocol utilizing entangled N-qubit states, enhancing security by limiting eavesdropper access and reducing potential information gain compared to BB84.

Contribution

It proposes a novel entanglement-based QKD protocol that improves security bounds over traditional single-qubit schemes like BB84.

Findings

Eavesdropper's information can be minimized to less than 30% of BB84 for N=2.

The protocol's security is at least comparable to BB84.

Limiting eavesdropper access to individual qubits enhances security.

Abstract

We present and analyze a quantum key distribution protocol based on sending entangled N-qubit states instead of single-qubit ones as in the trail-blazing scheme by Bennett and Brassard (BB84). Since the qubits are sent individually, an eavesdropper is limited to accessing them one by one. In an intercept-resend attack, this fundamental restriction allows one to make the eavesdropper's information on the transmitted key vanish if even one of the qubits is not intercepted. The implied upper bound 1/(2N) for Eve's information is further shown not to be the lowest since in the case N = 2, the information can be reduced to less than 30% of that in BB84. In general, the protocol is at least as secure as BB84.