High fidelity quantum state transfer in electromechanical systems with intermediate coupling

TL;DR

This paper proposes a scheme for high fidelity quantum state transfer in a hybrid electromechanical system with intermediate coupling, demonstrating that optimal transfer occurs when the coupling strengths are comparable.

Contribution

It introduces a novel intermediate coupling regime for high fidelity quantum state transfer in hybrid systems, challenging the conventional focus on weak or strong coupling regimes.

Findings

High fidelity transfer is achievable in the intermediate coupling regime.

Both small and large coupling regimes are insufficient for high fidelity transfer.

Numerical analysis includes decoherence effects to validate results.

Abstract

Hybrid quantum systems usually consist of two or more subsystems, which may take the advantages of the different systems. Recently, the hybrid system consisting of circuit electromechanical subsystems have attracted great attention due to its advanced fabrication and scalable integrated photonic circuit techniques. Here, we propose a scheme for high fidelity quantum state transfer between a superconducting qubit and a nitrogen-vacancy center in diamond, which are coupled to a superconducting transmission-line resonator with coupling strength $g_1$ and a nanomechanical resonator with coupling strength $g_2$, respectively. Meanwhile, the two resonators are parametrically coupled with coupling strength $J$. The system dynamics, including the decoherence effects, is numerical investigated. It is found that both the small ($J \ll \{g_1, g_2\}$) and large ($J \gg \{g_1, g_2\}$) coupling regimes of this hybrid system can not support high fidelity quantum state transfer before significant technique advances. However, in the intermediate coupling regime ($J \sim g_1 \sim g_2$), in contrast to a conventional wisdom, high fidelity quantum information transfer can be implemented, providing a promising route towards high fidelity quantum state transfer in similar coupled resonators systems.