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arXiv · 2301.13285

Correspondence between entangled states and entangled bases under local transformations

Florian Pimpel·Martin J. Renner·Armin Tavakoli
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Abstract

We investigate whether pure entangled states can be associated to a measurement basis in which all vectors are local unitary transformations of the original state. We prove that for bipartite states with a local dimension that is either $2, 4$ or $8$, every state corresponds to a basis. Via numerics we strongly evidence the same conclusion also for two qutrits and three qubits. However, for some states of four qubits we are unable to find a basis, leading us to conjecture that not all quantum states admit a corresponding measurement. Furthermore, we investigate whether there can exist a set of local unitaries that transform \textit{any} state into a basis. While we show that such a state-independent construction cannot exist for general quantum states, we prove that it does exist for real-valued $n$-qubit states if and only if $n=2,3$, and that such constructions are impossible for any multipartite system of an odd local dimension. Our results suggest a rich relationship between entangled states and iso-entangled measurements with a strong dependence on both particle numbers and dimension.

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Florian Pimpel, Martin J. Renner, Armin Tavakoli. 2023-06-29. Correspondence between entangled states and entangled bases under local transformations. https://doi.org/10.1103/physreva.108.022220

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