美国加州理工学院Andrei Faraon团队研究了具有自旋的单光子级可扩展微波到光学换能器。2025年4月22日出版的《自然—物理学》杂志发表了这项成果。
单光子的微波光转导将在未来超导量子器件的互连中发挥重要作用。已经开发了各种换能器，通过利用普克尔效应等非线性现象以及机电、压电
和光机耦合的组合来耦合微波和光学模式。然而，这些非线性的有限强度需要使用高质量因子谐振器，这可能需要复杂的纳米制造方法。稀土离子掺杂晶体具有高质量的原子共振，导致有效的二阶非线性，比传统材料中的非线性强许多数量级。
研究组使用掺杂在YVO4晶体中的镱-171离子来实现片上微波到光学换能器。如果没有工程光学腔，他们可以在输入低至1.24（9）个光子的情况下，通过增加噪声来实现百分比级效率。研究组演示了来自两个同时工作的换能器的光子的干涉，这是由原子跃迁的固有匹配频率实现的。该研究结果将稀土离子基器件确立为具有竞争力的转导平台，并为超导量子机器的远程换能器辅助纠缠铺平了道路。
附：英文原文
Title: Scalable microwave-to-optical transducers at the single-photon level with spins
Author: Xie, Tian, Fukumori, Rikuto, Li, Jiahui, Faraon, Andrei
Issue&Volume: 2025-04-22
Abstract: Microwave-to-optical transduction of single photons will play an essential role in interconnecting future superconducting quantum devices. Various transducers have been developed that couple microwave and optical modes by utilizing nonlinear phenomena such as the Pockels effect and a combination of electromechanical, piezoelectric and optomechanical couplings. However, the limited strength of these nonlinearities necessitates the use of high-quality-factor resonators that can require sophisticated nanofabrication methods. Rare-earth-ion-doped crystals have high-quality atomic resonances that result in effective second-order nonlinearities that are many orders of magnitude stronger than those in conventional materials. Here we use ytterbium-171 ions doped in an YVO4 crystal to implement an on-chip microwave-to-optical transducer. Without an engineered optical cavity, we achieve per-cent-level efficiencies with an added noise referred to the input as low as 1.24(9) photons. We demonstrate the interference of photons originating from two simultaneously operated transducers, enabled by the inherently matching frequencies of the atomic transitions. Our results establish rare-earth-ion-based devices as a competitive platform for transduction and pave the way towards the remote transducer-assisted entanglement of superconducting quantum machines.
DOI: 10.1038/s41567-025-02884-y
Source: https://www.nature.com/articles/s41567-025-02884-y