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

Understand

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.