Entanglement harvesting of three Unruh-DeWitt detectors

Abstract

We analyze a tripartite entanglement harvesting protocol with three Unruh-DeWitt detectors adiabatically interacting with a quantum scalar field. We consider linear, equilateral triangular, and scalene triangular configurations for the detectors. We find that, under the same parameters, more entanglement can be extracted in the linear configuration than the equilateral one, consistent with single instantaneous switching results. No bipartite entanglement is required to harvest tripartite entanglement. Furthermore, we find that tripartite entanglement can be harvested even if one detector is at larger spacelike separations from the other two than in the corresponding bipartite case. We also find that for small detector separations bipartite correlations become larger than tripartite ones, leading to an apparent violation of the Coffman-Kundu-Wootters (CKW) inequality. We show that this is not a consequence of our perturbative expansion but that it instead occurs because the harvesting qubits are in a mixed state.

Characterization of non-perturbative qubit channel induced by a quantum field

“…For two-qubit systems, in particular, where two-party communication is most naturally set in, there has been quite a few known results in the non-perturbative regimes in flat spacetimes (see, e.g., the thorough work in [10,11,27]), though this has changed recently to include curved backgrounds exploiting the sort of generalities we consider here [13-15, 29, 62]. The three-qubit system calculation has been only confined to entanglement and mutual information harvesting in flat space [26,97,98], and there is also an example on sabotaging of correlations where they consider arbitrary number of detectors were considered in flat space) [25]. It is actually not difficult to show that there are ways to organize these calculations in the same spirit as this work in curved spacetimes.…”