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A New Strategy of Quantum-State Estimation for Achieving the Cramer-Rao Bound

Koji Usami·Yoshihiro Nambu·Yoshiyuki Tsuda·Keiji Matsumoto·Kazuo Nakamura
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Abstract

We experimentally analyzed the statistical errors in quantum-state estimation and examined whether their lower bound, which is derived from the Cramer-Rao inequality, can be truly attained or not. In the experiments, polarization states of bi-photons produced via spontaneous parametric down-conversion were estimated employing tomographic measurements. Using a new estimation strategy based on Akaike's information criterion, we demonstrated that the errors actually approach the lower bound, while they fail to approach it using the conventional estimation strategy.

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Koji Usami, Yoshihiro Nambu, Yoshiyuki Tsuda, Keiji Matsumoto, Kazuo Nakamura. 2002-09-11. A New Strategy of Quantum-State Estimation for Achieving the Cramer-Rao Bound. https://doi.org/10.1103/physreva.68.022314

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