Physical and logical qubits
In quantum computing, a qubit is a unit of information analogous to a bit (binary digit) in classical computing, but it is affected by quantum mechanical properties such as superposition and entanglement which allow qubits to be in some ways more powerful than classical bits for some tasks. Qubits are used in quantum circuits and quantum algorithms composed of quantum logic gates to solve computational problems, where they are used for input/output and intermediate computations.
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.