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Alternative representation of N \times N density matrix

Stanislaw Kryszewski·Mateusz Zachcial
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Abstract

We use polarization operators known from quantum theory of angular momentum to expand the $N \times N$ dimensional density operators. Thereby, we construct generalized Bloch vectors representing density matrices. We study their properties and derive positivity conditions for any $N$. We also apply the procedure to study Bloch vector space for a qubit and a qutrit.

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Stanislaw Kryszewski, Mateusz Zachcial. 2006-02-06. Alternative representation of N \times N density matrix. https://arxiv.org/abs/quant-ph/0602065

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