Schrödinger–HJW theorem
Concept in quantum information theory / From Wikipedia, the free encyclopedia
In quantum information theory and quantum optics, the Schrödinger–HJW theorem is a result about the realization of a mixed state of a quantum system as an ensemble of pure quantum states and the relation between the corresponding purifications of the density operators. The theorem is named after physicists and mathematicians Erwin Schrödinger,[1] Lane P. Hughston, Richard Jozsa and William Wootters.[2] The result was also found independently (albeit partially) by Nicolas Gisin,[3] and by Nicolas Hadjisavvas building upon work by Ed Jaynes,[4][5] while a significant part of it was likewise independently discovered by N. David Mermin.[6] Thanks to its complicated history, it is also known by various other names such as the GHJW theorem,[7] the HJW theorem, and the purification theorem.