Two-state quantum system

• abstract: In quantum mechanics, a two-state system (also known as a two-level system or TLS) is a system which has two possible quantum states. An example of a two-state system is the spin of a spin-1/2 particle such as an electron, whose spin can have values +ħ/2 or −ħ/2, where ħ is the reduced Planck constant.

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