Quantum mechanics
Quantum mechanics is a field of physics that describes the behaviour of matter and energy on the smallest scale. It looks at atoms and subatomic particles as well as phenomena such as superposition (the simultaneous existence of several states) and entanglement (location-independent coupling of particles).
Qubit
A qubit is the basic unit of information in a quantum computer. In contrast to a classical bit, a qubit can be 0 and 1 at the same time thanks to the superposition principle. This allows quantum computers to perform many calculations in parallel, giving them a potentially much higher computing power than classical computers.