High-bandwidth, variable-resistance differential noise thermometry

Citation:

A. V. Talanov, Waissman, J. , Taniguchi, T. , Watanabe, K. , and Kim, P. . 2021. “High-Bandwidth, Variable-Resistance Differential Noise Thermometry”. Review Of Scientific Instruments, 92, Pp. 014904. doi:10.1063/5.0026488.

Abstract:

We develop Johnson noise thermometry applicable to mesoscopic devices with variable source impedance with high bandwidth for fast data acquisition. By implementing differential noise measurement and two-stage impedance matching, we demonstrate noise measurement in the frequency range 120-250 MHz with a wide sample resistance range 30 Ω-100 kΩ tuned by gate voltages and temperature. We employ high-frequency, single-ended low noise amplifiers maintained at a constant cryogenic temperature in order to maintain the desired low noise temperature. We achieve thermometer calibration with temperature precision up to 650 µK on a 10 K background with 30 s of averaging. Using this differential noise thermometry technique, we measure thermal conductivity on a bilayer graphene sample spanning the metallic and semiconducting regimes in a wide resistance range, and we compare it to the electrical conductivity.