Quantum physics describes the world of the smallest particles, such as neutrons, protons, electrons, or photons. The term “quant” refers to a discrete value of a physical quantity. A quant can only be created or destroyed as a whole; these quanta ultimately give the quantum computer its name.

A quant in a quantum computer can be an atom, an ion, or an electron.

Computers and smartphones operate using bits. A bit can only assume two states: either [1] or [0]. Drawing on this concept of bits, the states that a quantum can assume in quantum computing are referred to as qubits, or quantum bits. Unlike classical bits, a qubit can exist in virtually any number of states.

However, there is a hurdle to overcome in the implementation of qubits, as the systems are very sensitive and unstable. To prepare qubits, it is therefore necessary to cool the system to the point where thermal motion has no disruptive effect.

This is achieved at temperatures near absolute zero, at −273.15 °C.