Extraction of genuine tripartite entanglement from the vacuum

Abstract

We demonstrate and characterize the extraction of genuine tripartite entanglement from the vacuum of a periodic cavity field. That is, three probe quantum systems (detectors) can become both bipartitely and tripartitely entangled without coming into causal contact, by means of interaction with a common quantum field. We do this by using an oscillator-detector model that forgoes the need for perturbation theory and which instead is solved exactly. We find that the extraction of tripartite entanglement is considerably easier than that of bipartite. As a secondary result, we also compare a periodic cavity with one that has Dirichlet boundary conditions. We find that the extraction of both bipartite and tripartite entanglement is more easily achieved using the former case.

Effect of acceleration on localized fermionic Gaussian states: From vacuum entanglement to maximally entangled states

“…That is, the particles that are produced due to the Unruh effect are correlated across the acceleration horizon. Interestingly, the vacuum entanglement has an operational meaning, as it can, in principle, be extracted by suitable detectors [10,11].…”

“…In these models, a two-level system is linearly coupled to a scalar field and the effect of finite time interactions is studied [9]. In particular, it was shown that entanglement can be extracted from vacuum correlations [10,11]. The process of extracting entanglement from the vacuum sometimes is referred to as "entanglement harvesting" [12].…”

Zero mode suppression of superluminal signals in light-matter interactions

“…In some contexts, such as UDW model coupled via derivative coupling, its effect can indeed be made negligible at the level of detector responses in appropriate limits [16], but in some other contexts it has significant impact on detector dynamics and entanglement [16,17,23,24]. There are also cases when the zero mode has been excluded by assumption from a setup with periodic boundary conditions (e.g., in [25][26][27][28][29]), thus it is of interest to further study the impact that the removal of the zero mode may have on the relativistic nature of the interaction, and in particular in the causality of the whole particle detector model.…”

Spatial entanglement of nonvacuum Gaussian states

“…After inserting the above into Eq. (22) and expanding the S nl blocks, we compute the covariance matrix of the reduced state of the lowest mode on the left and on the right side of the mirror. It has the form σ out | 11 of Eq.…”

“…Recently, however, a thorough analysis of vacuum entanglement was performed for massive fields [20], where sudden death of vacuum entanglement as a function of the distance between the modes was observed. It has also been shown that vacuum entanglement can be used to violate Bell's inequalities [5][6][7][8]15], can be multipartite [21,22], and that for massless fields, it persists between timelike separated regions [23]. It can also be resonantly enhanced with the use of a moving cavity [24].…”