Hashisaka Masayuki, Ota Tomoaki, Yamagishi Masakazu, Fujisawa Toshimasa, Muraki Koji
Department of Physics, Tokyo Institute of Technology, 2-12-1-H81 Ookayama, Meguro, Tokyo 152-8551, Japan.
NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato-Wakamiya, Atsugi, Kanagawa 243-0198, Japan.
Rev Sci Instrum. 2014 May;85(5):054704. doi: 10.1063/1.4875588.
We report a cross-correlation measurement system, based on a new approach, which can be used to measure shot noise in a mesoscopic conductor at milliKelvin temperatures. In contrast to other measurement systems in which high-speed low-noise voltage amplifiers are commonly used, our system employs homemade transimpedance amplifiers (TAs). The low input impedance of the TAs significantly reduces the crosstalk caused by unavoidable parasitic capacitance between wires. The TAs are designed to have a flat gain over a frequency band from 2 kHz to 1 MHz. Low-noise performance is attained by installing the TAs at a 4 K stage of a dilution refrigerator. Our system thus fulfills the technical requirements for cross-correlation measurements: low noise floor, high frequency band, and negligible crosstalk between two signal lines. Using our system, shot noise generated at a quantum point contact embedded in a quantum Hall system is measured. The good agreement between the obtained shot-noise data and theoretical predictions demonstrates the accuracy of the measurements.
我们报告了一种基于新方法的互相关测量系统，该系统可用于在毫开尔文温度下测量介观导体中的散粒噪声。与通常使用高速低噪声电压放大器的其他测量系统不同，我们的系统采用自制的跨阻放大器（TA）。TA的低输入阻抗显著降低了由导线之间不可避免的寄生电容引起的串扰。TA被设计为在2 kHz至1 MHz的频带上具有平坦的增益。通过将TA安装在稀释制冷机的4 K级来实现低噪声性能。因此，我们的系统满足了互相关测量的技术要求：低本底噪声、高频带以及两条信号线之间可忽略不计的串扰。使用我们的系统，测量了嵌入量子霍尔系统中的量子点接触处产生的散粒噪声。获得的散粒噪声数据与理论预测之间的良好一致性证明了测量的准确性。
