Exploring the relationship between the faithfulness and entanglement of two qubits
arXiv:2102.10121 · doi:10.1103/PhysRevA.103.042417
Abstract
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 polarization-entangled 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.
9 pages, 6 figures
References in corpus (9)
- Entanglement detection
- High-dimensional quantum communication: benefits, progress, and future challenges
- Loss of polarization entanglement in a fiber-optic system with polarization mode dispersion in one optical path
- Sudden Death of Entanglement induced by Polarization Mode Dispersion
- Nonlocal PMD compensation in the transmission of non-stationary streams of polarization entangled photons
- Geometry of faithful entanglement
- Quantum-Inspired Hierarchy for Rank-Constrained Optimization
- Exploring classical correlations in noise to recover quantum information using local filtering
- Detecting Entanglement in Unfaithful States