Qubit

Basic unit of quantum information

In quantum computing, a qubit or quantum bit is a basic unit of quantum information, the quantum version of the classic binary bit. A qubit can be physically realized with a two-state (or two-level) quantum-mechanical system, one of the simplest quantum systems displaying the peculiarity of quantum mechanics. Examples include the spin of the electron in which the two levels can be taken as spin up and spin down; or the polarization of a single photon in which the two spin states (left-handed and the right-handed circular polarization) can also be measured as horizontal and vertical linear polarization.

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