Glossary of terminology and terms

No-cloning theorem

The no-cloning theorem states that it is impossible to create an identical copy of an arbitrary unknown quantum state.

State space

A state space is the set of all possible states of a system.

Quantum decoherence

Quantum decoherence is the loss of quantum coherence. Which is to say a quantum state returns to a classical state.

Quantum entanglement

Quantum entanglement is when two or more particles are generated, interacting, or sharing spatial proximity in such a way that the quantum state of each particle cannot be described independently from the others.

Quantum system

A quantum system, such as a quantum clock, whose primary function is to generate a quantum state and utilise this state for a purpose (E.g. magnetic field sensing).

Systems which utilise quantum technologies

These are systems which are designed to perform a function and merely use a quantum system as a subsystem to achieve the overall objective (e.g. a navigation system).

Qubit

A qubit is the basic unit of quantum information and can exist in superpositions of the |0⟩ and |1⟩ states. Qubits are analogous to classical bits used in classical computers.