Pure State Entanglement Harvesting in Quantum Field Theory

TL;DR

This paper introduces a high-efficiency protocol for extracting pure state entanglement from quantum fields, overcoming previous limitations by avoiding mixed states and ultraviolet divergence, and establishing a trade-off with energy cost.

Contribution

The authors propose a novel protocol that extracts pure state entanglement from quantum fields using bi-linear interactions, achieving infinite entanglement without ultraviolet divergence.

Findings

Protocol enables extraction of large entanglement amounts.

Extracted entanglement remains finite despite ultraviolet cutoff.

Trade-off exists between entanglement amount and energy cost.

Abstract

Quantum fields in vacuum states carry an infinite amount of quantum entanglement, and its entanglement entropy has the ultraviolet divergence. Harvesting protocols of the vacuum entanglement had been investigated, but its efficiency is very low to date. The main reason of the low efficiency originates from the fact that the extracted entanglement is embedded in a mixed state of two external devices. We propose a general protocol with high efficiency by extracting pure state entanglement from the field. We only use bi-linear interactions between the fields and external devices. Even though the ultraviolet cutoff remains finite, the protocol is capable of extracting a huge amount of entanglement. Hence the infinite amount of entanglement extraction is attained without the ultraviolet divergence of the field entanglement entropy in a continuum limit. There exists a trade-off relation between the extracted entanglement and its energy cost.