Detecting Entanglement in Unfaithful States

Zhan, Yong-Tao; Lo, Hoi-Kwong

doi:10.48550/arxiv.2010.06054

Cited by 3 publications

(4 citation statements)

References 38 publications

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“…It tolerates white noise up to p = 0.47 (Fig. 2b), which is as performant as witnesses that use non-local operators [21].…”

Section: Application Of the Methods To Tripartite Qubit Statesmentioning

confidence: 77%

“…What is noteworthy, though, is the witness derived for the W state, a non-stabilizer state. For such a state, it is not possible to find stabilizing operators that are the tensor products of single-qubit operations [14,21]. Therefore, witnesses derived in previous works for the W state required non-local measurements.…”

Section: Application Of the Methods To Tripartite Qubit Statesmentioning

confidence: 99%

See 1 more Smart Citation

Machine Learning-Derived Entanglement Witnesses

Zhu¹,

Wu²,

Li³

2021

Preprint

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“…It tolerates white noise up to p = 0.47 (Fig. 2b), which is as performant as witnesses that use non-local operators [21].…”

Section: Application Of the Methods To Tripartite Qubit Statesmentioning

confidence: 77%

Section: Application Of the Methods To Tripartite Qubit Statesmentioning

confidence: 99%

Machine Learning-Derived Entanglement Witnesses

Zhu¹,

Wu²,

Li³

2021

Preprint

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“…Recent theoretical and experimental advances signify the urgent need to identify experiment-friendly entanglement detection protocols which can also certify unfaithful entanglement. In the short time since the discovery of unfaithful entanglement, advances have already been made to study its structure and detection (Gühne et al, 2020;Zhan and Lo, 2020). Here we recast the entanglement detection problem into a quantum preparation game (Weilenmann et al, 2020a), and use the solution of the resulting optimisation problem as experiment-friendly witnesses capable of certifying the entanglement dimension of bipartite highdimensional states.…”

Section: Discussionmentioning

confidence: 99%

Optimized Detection of High-Dimensional Entanglement

Xing

Guo

et al. 2021

Phys. Rev. Lett.

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Entanglement detection is one of the most conventional tasks in quantum information processing. While most experimental demonstrations of high-dimensional entanglement rely on fidelity-based witnesses, these are powerless to detect entanglement within a large class of entangled quantum states, the so-called unfaithful states. In this paper, we introduce a highly flexible automated method to construct optimal tests for entanglement detection given a bipartite target state of arbitrary dimension, faithful or unfaithful, and a set of local measurement operators. By restricting the number or complexity of the considered measurement settings, our method outputs the most convenient protocol to test the entanglement of the target state in the lab. Using the 3-setting protocols generated by our method, we experimentally certify 2-and 3-dimensional entanglement in 4-dimensional unfaithful states. I. INTRODUCTIONEntanglement is the bedrock of most quantum information processing protocols (Gühne and Tóth, 2009; Horodecki et al., 2009). It is a key resource in quantum teleportation (Bennett et al., 1993), entanglement-based quantum key distribution (QKD) (Yin et al., 2017) and quantum communication complexity (Buhrman et al., 2010). Generating high-quality entangled states and detecting them reliably is a crucial prerequisite to conduct any quantum communication task.

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“…Still, this method for entanglement detection is limited by the minimum value that α can have, and will thus have the drawback (common to every entanglement witness approach) of not being able to detect all entangled states. The term unfaithful has been applied to the set of states that cannot be detected by any construction of a fidelity witness [2][3][4]. Recently, an analytical method for determining the faithfulness of any two-qubit state was provided [3].…”

Section: Introductionmentioning

confidence: 99%

Exploring the relationship between the faithfulness and entanglement of two qubits

Riccardi,

Jones,

et al. 2021

Preprint

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A conceptually simple and experimentally prevalent class of entanglement witnesses, known as fidelity witnesses, detect entanglement via a state's fidelity with a pure reference state. While existence proofs guarantee that a suitable witness can be constructed for every entangled state, such assurances do not apply to fidelity witnesses. Recent results have found that entangled states that cannot be detected by a fidelity witness, known as unfaithful states, are exceedingly common among bipartite states. In this paper, we show that even among two-qubit states, the simplest of all entangled states, unfaithful states can be created through a suitable application of decoherence and filtering to a Bell state. We also show that the faithfulness is not monotonic to entanglement, as measured by the concurrence. Finally, we experimentally verify our predictions using polarizationentangled photons and specifically demonstrate a situation where an unfaithful state is brought to faithfulness at the expense of further reducing the entanglement of the state.

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Detecting Entanglement in Unfaithful States

Cited by 3 publications

References 38 publications

Machine Learning-Derived Entanglement Witnesses

Machine Learning-Derived Entanglement Witnesses

Optimized Detection of High-Dimensional Entanglement

Exploring the relationship between the faithfulness and entanglement of two qubits

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