Entangled Quantum Key Distribution with a Biased Basis Choice

TL;DR

This paper explores a biased basis choice in entangled quantum key distribution to enhance efficiency, analyzing optimal bias, error correction, and finite key effects, and demonstrates a 79% increase in key rate in a practical system.

Contribution

It introduces a practical implementation of biased basis choice in entangled QKD, showing significant efficiency improvements over unbiased schemes.

Findings

Achieved a 79% increase in secure key rate with biased basis.

Demonstrated stable operation over 6 hours with high bias.

Validated theoretical predictions with experimental results.

Abstract

We investigate a quantum key distribution (QKD) scheme which utilizes a biased basis choice in order to increase the efficiency of the scheme. The optimal bias between the two measurement bases, a more refined error analysis, and finite key size effects are all studied in order to assure the security of the final key generated with the system. We then implement the scheme in a local entangled QKD system that uses polarization entangled photon pairs to securely distribute the key. A 50/50 non-polarizing beamsplitter with different optical attenuators is used to simulate a variable beamsplitter in order to allow us to study the operation of the system for different biases. Over 6 hours of continuous operation with a total bias of 0.9837/0.0163 (Z/X), we were able to generate 0.4567 secure key bits per raw key bit as compared to 0.2550 secure key bits per raw key bit for the unbiased case. This represents an increase in the efficiency of the key generation rate by 79%.