Optimal dimensionality for quantum cryptography

On the Optimal Mean Photon Number for Quantum Cryptography

The optimal mean photon number (μ) for quantum cryptography is the average photon number per transmitted pulse that results in the highest delivery rate of distilled cryptographic key bits, given a specific system scenario and set of assumptions about Eve’s capabilities. Although many experimental systems have employed a mean photon number (μ) of 0.1 in practice, several research teams have poi...

Optimal receiver for quantum cryptography with two coherent states

From the conceptual point of view, the simplest quantum protocol for establishing a cryptographic key is a transmission of a random sequence of two non-orthogonal states [1]. What makes this protocol secure, is the impossibility of discriminating between these two states with certainty. Thus, any attempt of eavesdropping inevitably generates noise in the transmission channel, which can be detec...

Quantum relays for long distance quantum cryptography

Quantum cryptography is on the verge of commercial application. One of its greatest limitations is over long distance—secret key rates are low and the longest fibre over which any key has been exchanged is currently 100 km. We investigate the quantum relay, which can increase the maximum distance at which quantum cryptography is possible. The relay splits the channel into sections and sends a d...

Quantum Cryptography

Quantum cryptography

This is a chapter on quantum cryptography for the book “A Multidisciplinary Introduction to Information Security” to be published by CRC Press in 2011/2012. The chapter aims to introduce the topic to undergraduate-level and continuing-education students specializing in information and communication technology.