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Properties of multi-partite dark states

Pieter Kok·Kae Nemoto·William J. Munro
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Abstract

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.

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Pieter Kok, Kae Nemoto, William J. Munro. 2002-01-29. Properties of multi-partite dark states. https://arxiv.org/abs/quant-ph/0201138

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