Morelli, S., Eltschka, C., Huber, M., & Siewert, J. (2024). Correlation constraints and the Bloch geometry of two qubits. Physical Review A, 109(1), Article 012423. https://doi.org/10.1103/PhysRevA.109.012423
E141-08 - Forschungsbereich Quantum Optics and Quantum Information
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Journal:
Physical Review A
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ISSN:
2469-9926
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Date (published):
19-Jan-2024
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Publisher:
AMER PHYSICAL SOC
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Peer reviewed:
Yes
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Keywords:
bipartite states; two-qubit states; local Bloch vectors; three-dimensional; quantum states
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Abstract:
We present an inequality on the purity of a bipartite state depending solely on the length difference of the local Bloch vectors. For two qubits this inequality is tight for all marginal states and so extends the previously known solution for the two-qubit marginal problem. With this inequality we construct a three-dimensional Bloch model of the two-qubit quantum state space in terms of Bloch lengths, providing a pleasing visualization of this high-dimensional state space. This allows to characterize quantum states by a strongly reduced set of parameters and to investigate the interplay between local properties of the marginal systems and global properties encoded in the correlations.
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Project title:
Control and complexity in quantum statistical mechanics: 101043705 (European Commission) HyperSpace: 101070168 (European Commission)
