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Updated: Feb 27, 2026

A Photonic System for Generating Unconditional Polarization-Entangled Photons Based on Multiple Quantum Interference
Published on: September 5, 2019
On Local Unitary Equivalence of Two and Three-qubit States
Bao-Zhi Sun1, Shao-Ming Fei2, Zhi-Xi Wang2
1School of Mathematics, Qufu Normal University, JiNing, Shandong, 273165, China. sun_bao_zhi@163.com.
Abstract:
We study the local unitary equivalence for two and three-qubit mixed states by investigating the invariants under local unitary transformations. For two-qubit system, we prove that the determination of the local unitary equivalence of 2-qubits states only needs 14 or less invariants for arbitrary two-qubit states. Using the same method, we construct invariants for three-qubit mixed states. We prove that these invariants are sufficient to guarantee the LU equivalence of certain kind of three-qubit states. Also, we make a comparison with earlier works.
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