Quantum Information Theory

Marked 'Not for examination', this closing enrichment section previews quantum information theory as another fast-developing research area, one focused on improving how information is stored using quantum computers. The book draws a direct contrast with today's computers: present-day computers store information in the form of 'bits', where a classical bit is strictly either 0 or 1. Quantum computers instead store information in the form of 'qubits' -- 'qubit' being short for quantum bit, and the basic unit of quantum information. A qubit is not restricted to being simply 0 or 1; it can also exist in a linear superposition of 0 and 1 at once. This extra freedom is what the book credits with reducing calculation time exponentially compared …