Bell state

English

Etymology

Named after John Stewart Bell (1928–1990), Irish physicist.

Noun

Bell state (plural Bell states)

1. (quantum information science) One of a set of four entangled states, namely ${\displaystyle |\Phi ^{+}\rangle ={1 \over {\sqrt {2}}}(|00\rangle +|11\rangle )}$, ${\displaystyle |\Phi ^{-}\rangle ={1 \over {\sqrt {2}}}(|00\rangle -|11\rangle )}$,    ${\displaystyle |\Psi ^{+}\rangle ={1 \over {\sqrt {2}}}(|01\rangle +|10\rangle )}$, and ${\displaystyle |\Psi ^{-}\rangle ={1 \over {\sqrt {2}}}(|01\rangle -|10\rangle )}$, where ${\displaystyle |xy\rangle :=|x\rangle \otimes |y\rangle }$; these are the simplest examples of entangled states.