W state

The W state is an entangledquantum state of three qubits which in the bra-ket notation has the following shape

${\displaystyle |\mathrm {W} angle ={\frac {1}{\sqrt {3}}}(|001 angle +|010 angle +|100 angle )}$

and which is remarkable for representing a specific type of multipartite entanglement and for occurring in several applications in quantum information theory. Particles prepared in this state reproduce the properties of Bell's theorem, which states that no classical theory of local hidden variables can produce the predictions of quantum mechanics. The state is named after Wolfgang Dür, who first reported the state together with Guifré Vidal, and Ignacio Cirac in 2000.