Analyzing Quantum Entanglement with the Schmidt Decomposition in Operator Space
Phys. Rev. Lett. 133, 040203 – Published 26 July, 2024
DOI: https://doi.org/10.1103/PhysRevLett.133.040203
Abstract
Characterizing entanglement is central for quantum information science. Special observables which indicate entanglement, so-called entanglement witnesses, are a widely used tool for this task. The construction of these witnesses typically relies on the observation that quantum states with a high fidelity to some entangled target state are entangled, too. We introduce a general method to construct entanglement witnesses based on the Schmidt decomposition of observables. The method works for two-particle and multiparticle systems and is strictly stronger than fidelity-based constructions. The resulting witnesses can also be used to quantify entanglement and to characterize its dimensionality. Finally, we present experimentally relevant examples, where our approach improves entanglement detection significantly.
