低频标准真空涨落的测量  

Measurement of standard vacuum noise at low frequencies

作　　者：薛佳[1] 秦际良 张玉驰[2] 李刚[1] 张鹏飞[1] 张天才[1] 彭堃墀[1] 

机构地区：[1]山西大学光电研究所,量子光学与光量子器件国家重点实验室,极端光学协同创新中心,太原030006 [2]山西大学物理电子工程学院,太原030006

出　　处：《物理学报》2016年第4期148-154,共7页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:91336107;61227902;61275210);山西省自然科学基金(批准号:2014021011-2)资助的课题~~

摘　　要：采用自平衡零拍方案,对低频段的标准量子真空涨落进行了测量.实验确定了该系统的饱和光功率约为3.2 mW.在10 Hz—400 kHz的频率范围内,系统的共模抑制比平均为55 dB,在100 Hz处高达63 dB,对激光经典技术噪声具有很强的抑制作用.当入射光功率为400μW时,真空涨落噪声达到11 dB.此低频量子真空噪声探测系统可广泛应用于量子计量和量子光学等研究领域.Vacuum fluctuation at audio frequencies is very important and interesting in many research fields, such as the gravitational wave detection, ultra-weak magnetic field measurement, and the research of quantum metrology, etc. Since the generation of squeezed light in 1985, most of the squeezed light have been generated and measured at radio frequencies （～MHz） as there has not been much technical noise at higher frequencies. In the Michelson-interferometer- based gravitational wave detection, the detection band has frequencies from a few to tens of thousands Hz. Measuring vacuum noise at such low frequencies is a challenge since we have to stabilize and control all the audio noises and the interferences from a variety of mechanical and electronic noises, therefore a very high classical noise suppression is needed when the measurement time increases. In order to measure the squeezed light of low frequencies, the standard vacuum noise at audio frequencies must be measured. In this paper, a balanced homodyne detection system for measuring the low-frequency quantum vacuum noises is reported. It is not trivial to extend the detected frequency to very low analysis frequencies. Through a self-made self-subtraction balanced homodyne configuration, which can eliminate the DC component of each photocurrent from the photodiode and the classical common-mode technical noise, the standard vacuum noise has been detected. The linearity of the vacuum noise power has been validated by varying the local oscillator power, showing that the saturation power of light incidence is about 3.2 mW. When the incident-light power is 400 μW, the standard vacuum noise is 11 dB higher than the electronic noise at 80 Hz. In the regime of about 80 Hz to 400 kHz, the linearity of the standard noise power as a function of incident laser power is verified. However, when the measurement is carried out at even lower frequencies, for example, 50 Hz, we may encounter some excess and non- stationary noises and find that the measured noise power is not

关 键 词：低频 量子噪声 平衡零拍探测 共模抑制比 

分 类 号：O431.2[机械工程—光学工程]