Cracking the Curious Case of the Cascade Protocol

Abstract

With the nature-powered quantum revolution gaining momentum, Quantum Computation and Quantum Information are all set to transform the landscape of all areas of science and technology. Quantum Cryptography is one such field which has witnessed tremendous progress in theory as well as in its practical implementation. Quantum Key Distribution is one of its integral parts and it necessarily requires the usage of an information reconciliation protocol to correct the errors present in the key bits transmitted via the physical system involved. Cascade is one such protocol which enjoys popularity among such system developers due to its simplicity and high error-correction efficiency. In this work, we identify, improve, interpret, and implement key optimizations from a practical viewpoint and give an algorithmic implementation of the Cascade protocol which would serve to increase its overall efficiency without changing its foundational structure. We also dig deep into the math and physical interpretation behind the values and expressions of key parameters and quantities of Cascade, which effectively make use of the cascade of errors unearthed by it so as to not only ensure an exponentially decreasing probability of any errors in the key bits with the passes of Cascade but also ensure that only the minimum possible information is leaked to a potential eavesdropper. Finally, we also give a visual walk-through of Cascade in action and support it with explanations at every step. By doing so, we aim to equip researchers and developers with an insight driven error correction tool which is sure to be useful in practice.

Keywords

• Cascade protocol
• error correction
• information reconciliation
• quantum communication
• quantum cryptography
• quantum key distribution (QKD)