Bell states

Last updated Jun 23, 2022

• Type note
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These are four maximally entangled states ¹ : $$\displaylines{
\ket{\phi^+} = \frac{1}{\sqrt 2}(\ket{00} + \ket{11}), \newline
\ket{\phi^-} = \frac{1}{\sqrt 2}(\ket{00} - \ket{11}), \newline
\ket{\Psi^+} = \frac{1}{\sqrt 2}(\ket{01} + \ket{10}), \newline
\ket{\Psi^-} = \frac{1}{\sqrt 2}(\ket{01} - \ket{10}). \newline
}$$