Generation of two-giant-atom entanglement in waveguide-QED systems

TL;DR

This paper investigates how two giant atoms coupled to a waveguide can generate and control quantum entanglement, revealing the impact of coupling configurations, phase shifts, and initial states on entanglement dynamics.

Contribution

It introduces a detailed analysis of entanglement generation in giant-atom waveguide-QED systems across different coupling configurations and initial states, highlighting the conditions for maximal and steady-state entanglement.

Findings

Steady-state entanglement exists for single-excitation states due to dark states.

Entanglement sudden birth can be achieved by phase shift adjustment.

Nested coupling yields the largest maximal entanglement, about ten times more than other configurations.

Abstract

We study the generation of quantum entanglement between two giant atoms coupled to a one-dimensional waveguide. Since each giant atom interacts with the waveguide at two separate coupling points, there exist three different coupling configurations in the two-atom waveguide system: separated, braided, and nested couplings. Within the Wigner-Weisskopf framework for single coupling points, the quantum master equations governing the evolution of the two giant atoms are obtained. For each coupling configuration, the entanglement dynamics of the two giant atoms is studied, including the cases of two different atomic initial states: single- and double-excitation states. It is shown that the generated entanglement depends on the coupling configuration, phase shift, and atomic initial state. For the single-excitation initial state, there exists steady-state entanglement for these three couplings due to the appearance of the dark state. For the double-excitation initial state, an entanglement sudden birth is observed via adjusting the phase shift. In particular, the maximal entanglement for the nested coupling is about one order of magnitude larger than those of separate and braided couplings. In addition, the influence of the atomic frequency detuning on the entanglement generation is studied. This work can be utilized for the generation and control of atomic entanglement in quantum networks based on giant-atom waveguide-QED systems, which have wide potential applications in quantum information processing.