Quantum Computers – Why Do They Pose A Threat To Digital Security?

What is Quantum Computing?

The International Patent Classification (IPC)¹ includes a category related to quantum computing titled: "G06N 10/00 Quantum computing, i.e. information processing based on quantum-mechanical phenomena".

The quantum-mechanical phenomena that make a computer a quantum computer are "qubits".

Qubits are quantum analogues of a classical bit (a qubit is a quantum bit)². In classical computers information is encoded in bits which can have values of zero or one. Qubits have two basis states of 0 and 1, but, using the principle of superposition, qubits can also be in a state which is a linear combination of the two basis states. It is it this quantum principle of superposition that differentiates a qubit from a bit.