近日，美国斯坦福大学的Amir H.Safavi-Naeini及其研究小组取得一项新进展。经过不懈努力，他们发现了光学预示的微波光子添加现象。相关研究成果已于2023年7月20日在国际知名学术期刊《自然—物理学》上发表。

该研究团队成功实现并演示了一个能够产生相关光学和微波光子的传感器。通过检测一个光学光子，研究人员成功产生了一个附加的微波光子，转换效率高达约35%。他们的装置采用千兆赫纳米机械共振器作为中介，通过强光机械和压电相互作用，有效地将光学和微波信号耦合在一起。

该研究展示了该换能器以5%的频率转换效率连续工作，输入参考附加噪声约为100。脉冲微波光子以15Hz的预示率产生，而器件中的光吸收产生的热噪声小于两个微波光子。通过提高系统效率和器件性能，实现远距离微波频率量子节点之间高纠缠率的目标是完全可行的。这一研究为量子信息处理和传输领域的进一步发展提供了有力支持。

据悉，光学频率高达几百太赫兹的光子可能成为远距离传播量子信息的关键途径。而实现大规模量子计算的有前途的方法之一是采用超导量子比特，在低得多的微波频率上操作，频率相较于光子低了4万倍。然而，为了实现这些量子系统在相当远的距离上的联网，必须解决这一频率差距的挑战。

附：英文原文

Title: Optically heralded microwave photon addition

Author: Jiang, Wentao, Mayor, Felix M., Malik, Sultan, Van Laer, Raphal, McKenna, Timothy P., Patel, Rishi N., Witmer, Jeremy D., Safavi-Naeini, Amir H.

Issue&Volume: 2023-07-20

Abstract: Photons with optical frequencies of a few hundred terahertz are perhaps the only way to distribute quantum information over long distances. Superconducting qubits, which are one of the most promising approaches for realizing large-scale quantum machines, operate on microwave photons at frequencies that are ~40,000 times lower. To network these quantum machines across appreciable distances, we must bridge this frequency gap. Here we implement and demonstrate a transducer that can generate correlated optical and microwave photons. We use it to show that by detecting an optical photon we generate an added microwave photon with an efficiency of ~35%. Our device uses a gigahertz nanomechanical resonance as an intermediary, which efficiently couples to optical and microwave channels through strong optomechanical and piezoelectric interactions. We show continuous operation of the transducer with 5% frequency conversion efficiency, input-referred added noise of ~100, and pulsed microwave photon generation at a heralding rate of 15Hz. Optical absorption in the device generates thermal noise of less than two microwave photons. Improvements of the system efficiencies and device performance are necessary to realize a high rate of entanglement generation between distant microwave-frequency quantum nodes, but these enhancements are within reach.

DOI: 10.1038/s41567-023-02129-w

Source: https://www.nature.com/articles/s41567-023-02129-w