Properties of multi-partite dark states

Kok, Pieter; Nemoto, Kae; Munro, William J.

Properties of multi-partite dark states

Authors

Kok, Pieter

Nemoto, Kae

Munro, William J.

Description

We investigate and define dark and semi-dark states for multiple qudit systems. For two-level systems, semi-dark and dark states are equivalent. We show that the semi-dark states are equivalent to the singlet states of the rotation group. They exist for many multiple qudit systems, whereas dark states are quite rare. We then show that when a dark state is collapsed onto another dark state of fewer parties, the resulting state is again dark. Furthermore, one can use two orthogonal multi-qudit dark states to construct a decoherence-free qudit.
5 pages, Revtex4