High-sensitivity microwave vector detection at extremely low-power levels for low-dimensional electron systems

TL;DR

This paper introduces a highly sensitive microwave vector detection system capable of measuring extremely low-power signals in low-dimensional electron systems, enabling precise phase and amplitude measurements at cryogenic temperatures.

Contribution

The authors develop a novel microwave detection system with unprecedented resolution for studying low-dimensional electron systems at very low power levels.

Findings

Achieved 0.005% amplitude resolution at 10 GHz.

Achieved 0.001° phase resolution at 10 GHz.

Enabled detection of tiny dipole moment changes in quantum wires.

Abstract

We present a high-sensitivity microwave vector detection system for studying the low-dimensional electron system embedded in the gaps of a coplanar waveguide at low temperatures. Using this system, we have achieved 0.005% and 0.001\textdegree resolutions in amplitude and phase variations, respectively, at 10 GHz in a magnetotransport measurement on a quantum-wire array with an average signal power less than $-$75 dBm into the sample at 0.3 K. From the measured phase variation, we can distinguish a very tiny change in the induced dipole moment of each quantum wire.