Algorithmic cooling
A qubit (or quantum bit) is a unit of information that can be in a superposition of two states, denoted as formula_1 and formula_2. The general superposition can be written as formula_3where formula_4 and formula_5. If one measures the state of the qubit in the orthonormal basis composed of formula_1 and formula_2, one gets the result formula_1 with probability formula_9 and the result formula_2 with probability formula_11.
Quantum computing
An example of an implementation of qubits of a quantum computer could start with the use of particles with two spin states: "down" and "up" (typically written formula_6 and formula_7, or formula_8 and formula_9). This is true because any such system can be mapped onto an effective spin-1/2 system.