The quantum one-time pad in the presence of an eavesdropper

TL;DR

This paper derives the optimal rate at which two parties can securely communicate using a quantum one-time pad in the presence of an eavesdropper, extending classical cryptographic principles to quantum settings.

Contribution

It provides the first single-letter formula for the quantum one-time pad rate under eavesdropping conditions, advancing quantum cryptography theory.

Findings

Derived the single-letter formula for quantum one-time pad rate

Established security conditions against eavesdroppers in quantum communication

Extended classical one-time pad concepts to quantum scenarios

Abstract

A classical one-time pad allows two parties to send private messages over a public classical channel -- an eavesdropper who intercepts the communication learns nothing about the message. A quantum one-time pad is a shared quantum state which allows two parties to send private messages or private quantum states over a public quantum channel. If the eavesdropper intercepts the quantum communication she learns nothing about the message. In the classical case, a one-time pad can be created using shared and partially private correlations. Here we consider the quantum case in the presence of an eavesdropper, and find the single letter formula for the rate at which the two parties can send messages using a quantum one-time pad.