Quantum information

Information that is held in the state of a [quantum system]?. The most popular unit of quantum information is the qubit, a two-state quantum system.

Quantum information differs from classical information in several respects, among which we note the following:

• it cannot generally be read or duplicated without disturbance;
• it can exist in superpositions of different values;

The ability to manipulate quantum information enables us to perform tasks that would be unachievable in a classical context, such as unconditionally secure transmission of information. Quantum information processing is the most general field that is concerned with quantum information.