近日，瑞士洛桑联邦理工学院的Tobias J. Kippenberg&Johann Riemensberger及其研究团队取得一项新进展。他们对电光光子集成电路中的基本电荷噪声进行了研究。相关研究成果已于2025年1月15日在国际知名学术期刊《自然—物理学》上发表。

据悉，理解热力学测量噪声对于电气和光学精密测量至关重要。这涉及到从半导体传感器（其中载流子的布朗运动构成了限制）到原子钟，或引力波检测中的光学参考腔（受限于热折射噪声和热弹性噪声）等各个领域。

该研究团队发现，载流子密度波动会在电光光子集成电路中引起一种噪声过程。研究表明，铌酸锂和钽酸锂光子集成微谐振器所表现出的噪声频率幂次为1.2，这与热折射噪声理论存在偏差。这种噪声与热力学电荷噪声相符，后者会导致电场波动，并通过电光材料的强普克尔效应进行转换。

这项研究结果确立了电约翰逊-奈奎斯特噪声作为电光集成光子的基本限制，这对于确定经典和量子器件的性能极限至关重要。

附：英文原文

Title: Fundamental charge noise in electro-optic photonic integrated circuits

Author: Zhang, Junyin, Li, Zihan, Riemensberger, Johann, Lihachev, Grigory, Huang, Guanhao, Kippenberg, Tobias J.

Issue&Volume: 2025-01-15

Abstract: Understanding thermodynamical measurement noise is of central importance for electrical and optical precision measurements. These range from semiconductor sensors, in which the Brownian motion of charge carriers poses limits, to optical reference cavities for atomic clocks or gravitational wave detection, which are limited by thermo-refractive and thermo-elastic noise. Here we find that charge-carrier density fluctuations give rise to a noise process in electro-optic photonic integrated circuits. We show that the noise exhibited by lithium niobate and lithium tantalate photonic integrated microresonators feature a frequency scaling to the power of 1.2, deviating from thermo-refractive noise theory. This noise is consistent with thermodynamical charge noise, which leads to electrical field fluctuations that are transduced via the strong Pockels effects of electro-optic materials. Our results establish electrical Johnson–Nyquist noise as the fundamental limitation for electro-optic integrated photonics, crucial for determining performance limits for both classical and quantum devices.

DOI: 10.1038/s41567-024-02739-y

Source: https://www.nature.com/articles/s41567-024-02739-y