Entanglement Dynamics of Two Qubits in a Common Bath

TL;DR

This paper develops an exact hierarchical equation approach to study the entanglement dynamics of two qubits in a common bath, revealing significant differences from previous approximate models and highlighting the impact of counter-rotating terms.

Contribution

It introduces a hierarchy equation method that avoids common approximations, providing more accurate insights into qubit entanglement dynamics in a shared environment.

Findings

Counter-rotating terms significantly affect entanglement evolution.

Exact solutions differ markedly from approximate models.

Double excitations influence entanglement behavior.

Abstract

We derive a set of hierarchical equations for qubits interacting with a Lorentz-broadened cavity mode at zero temperature, without using the rotating-wave, Born, and Markovian approximations. We use this exact method to reexamine the entanglement dynamics of two qubits interacting with a common bath, which was previously solved only under the rotating-wave and single-excitation approximations. With the exact hierarchy equation method used here, we observe significant differences in the resulting physics, compared to the previous results with various approximations. Double excitations due to counter-rotating-wave terms are also found to have remarkable effects on the dynamics of entanglement.