Related papers: Spin entanglement, decoherence and Bohm's EPR para…
Entanglement is one of the most fascinating concepts of modern physics. In striking contrast to its abstract, mathematical foundation, its practical side is, however, remarkably underdeveloped. Even for systems of just two orbitals or sites…
We discuss the conclusions that can be drawn on a recent experimental micro-macro entanglement test [F. De Martini, F. Sciarrino, and C. Vitelli, Phys. Rev. Lett. 100, 253601 (2008). The system under investigation is generated through…
Optical lossless beam splitters are frequently encountered in fundamental physics experiments regarding the nature of light, including "which-way" determination of light particles, N. Bohr's complementarity principle, or the EPR paradox and…
Traditionally, quantum entanglement has played a central role in foundational discussions of quantum mechanics. The measurement of correlations between entangled particles can exhibit results at odds with classical behavior. These…
We address the experimental determination of entanglement for systems made of a pair of polarization qubits. We exploit quantum estimation theory to derive optimal estimators, which are then implemented to achieve ultimate bound to…
We present a novel approach to look for the existence of maximum entanglement in a system of two identical quantum dots coupled by the Forster process and interacting with a classical laser field. Our approach is not only able to explain…
In order to assess inelastic effects on two fermion entanglement production, we address an exactly solvable two-particle scattering problem where the target is an excitable scatterer. Useful entanglement, as measured by the two particle…
Photonic graph states, quantum light states where multiple photons are mutually entangled, are key resources for optical quantum technologies. They are notably at the core of error-corrected measurement-based optical quantum computing and…
We establish a quantitative relation between local spin polarization and quantum entanglement in two-qubit systems by deriving an upper bound on the concurrence at fixed local polarizations, showing that increasing polarization constrains…
We consider a class of entangled states of a quantum system (S) and a second system (A) where pure states of the former are correlated with mixed states of the latter, and work out the entanglement measure with reference to the nearest…
We present an entanglement criterion for two mode squeezed states which relies on particle counting only. The proposed inequality is optimal for the state under consideration and robust against particle losses up to 2/3. As it does not…
Understanding the resource consumption in distributed scenarios is one of the main goals of quantum information theory. A prominent example for such a scenario is the task of quantum state merging where two parties aim to merge their parts…
We discuss anomalous decoherence effects at zero and finite temperatures in driven coupled quantum spin systems. By numerical simulations of the quantum master equation, it is found that the entanglement of two coupled spin qubits exhibits…
Particle decays do not constitute a spin ``measurement'' in the quantum-mechanical sense, but still modify the spin state, in particular for an entangled system. We show that for a spin-entangled pair of particles the entanglement of the…
An entangled quantum state is considered by applying a local photon excitation to each mode of an entangled coherent state. The entanglement property is investigated in terms of the entropy of entanglement. It is shown that applying a…
We investigate theoretically the use of non-ideal ferromagnetic contacts as a mean to detect quantum entanglement of electron spins in transport experiments. We use a designated entanglement witness and find a minimal spin polarization of…
Manipulation of spin states at the single-atom scale underlies spin-based quantum information processing and spintronic devices. Such applications require protection of the spin states against quantum decoherence due to interactions with…
We analyse decoherence properties of entangled coherent states (ECSs) due to channel losses, and compare to the performance of bi-photon Bell states. By employing the concept of "entanglement of formation" (EOF), the degradation of fidelity…
We formulate an entanglement criterion using Peres-Horodecki positive partial transpose operations combined with the Schr\"odinger-Robertson uncertainty relation. We show that any pure entangled bipartite and tripartite state can be…
In the paper, the EPR paradox is explored by the approach of quantum supervaluationism that leads to a "gappy" semantics with the propositions giving rise to truth-value gaps. Within this approach, the statement, which asserts that in the…