Nonlocal Young tests with Einstein-Podolsky-Rosen-correlated particle pairs

Abstract

We evaluate the nonlocal spatial interference displayed by Einstein-Podolsky-Rosen entangled particle pairs after they pass through a double-grating arrangement. An entanglement criterion is derived which serves to certify the underlying entanglement only from the observed spatial correlations. We discuss the robustness of the scheme along with a number of possible realizations with matter waves.

Generating and detecting entangled cat states in dissipatively coupled degenerate optical parametric oscillators

“…To certify the presence of entanglement in the generated states, we apply an entanglement criterion which is formulated in terms of modular variables [47][48][49][50][51]. By virtue of these, the criterion is sensitive to periodic structures in the states, which comprises entangled cat states as the two-component case.…”

“…To this end, we first specify the theoretical model and justify in some detail the generic expectation that entangled cat states can be produced in this setup. Then we recapitulate the entanglement criterion applied in the article, which, by construction, detects entanglement in two-mode entangled cat states [47][48][49][50][51]. Subsequently, we determine the threshold parameters under which entangled cat states (or states that are sufficiently close to these) are detectably present in the system.…”

Proposal for a macroscopic test of local realism with phase-space measurements

“…Therefore, obtaining | p 1 , p 2 |Ψ θφ | 2 is sufficient for evaluating X (θ) ⊗X(φ) = dp 1 dp 2 cos(p 1 L/ ) cos(p 2 L/ ) | p 1 , p 2 |Ψ θφ | 2 . It is known that in the far-field approximation [10]…”

“…This is closer in spirit to the original EPR argument which uses phase space description, a natural concept in the classical world, to better address the reality and locality problems of quantum mechanics. Notably, the Wigner function associated with the entangled state used in the EPR argument, the so called EPR state, is non-negative everywhere [10]. That is why, Bell argued that EPR states do not lead to a violation of the inequalities derived from locality and hidden variable assumptions [11].…”

“…We then proceed with identification of the relevant entangled state, explicitly showing the violation. Finally, in Sections IV and V we show how the entire test can be implemented in a double (multi-slit) grating setup [10]. Grating techniques have been used to experimentally demonstrate quantum matter waves [27].…”