Entanglement Generation and Decoherence in a Two-Qubit System Mediated by Relativistic Quantum Field

TL;DR

This paper investigates how two qubits become entangled through a relativistic quantum field, analyzing decoherence, causality, and quantum correlations using the closed-time path formalism.

Contribution

It provides a detailed analysis of entanglement generation and decoherence in a relativistic quantum field-mediated two-qubit system, highlighting causality constraints.

Findings

Entanglement is only generated when both spins are causally connected.

Spin correlations can exist without entanglement.

Decoherence arises from particle creation into the environment.

Abstract

Motivated by the Bose et al.-Matletto-Vedral (BMV) proposal for detecting quantum superposition of spacetime geometries, we study a toy model of a quantum entanglement generation between two spins (qubits) mediated by a relativistic free scalar field. After time evolution, spin correlation is generated through the interactions with the field. Because of the associated particle creation into an open system, the quantum state of spins is partially decohered. In this paper, we give a comprehensive study of the model based on the closed-time path formalism, focussing on relativistic causality and quantum mechanical complementarity. We calculate various quantities such as spin correlations, entanglement entropies, mutual information and negativity, and study their behaviors in various limiting situations. In particular, we calculate the mutual information of the two spins and compare it with spin correlation functions. We also discuss why no quantum entanglement can be generated unless both spins are causally affected by one another while spin correlations are generated.