Characterization of Tunnel Diode Oscillator for Qubit Readout Applications

TL;DR

This paper presents a cryogenic tunnel diode oscillator optimized for scalable qubit readout, demonstrating superior stability, low power consumption, and tunability suitable for integration in quantum computing systems.

Contribution

It introduces a compact, low-power tunnel diode oscillator with enhanced stability and tunability, tailored for large-scale qubit readout applications at cryogenic temperatures.

Findings

Achieved phase noise of -115 dBc/Hz at 1 MHz offset.

Demonstrated frequency tunability of 10 MHz.

Operates effectively at 140 MHz for qubit readout.

Abstract

We developed a tunnel diode oscillator and characterized its performance, highlighting its potential applications in the quantum state readout of electrons in semiconductors and electrons on liquid helium. This cryogenic microwave source demonstrates significant scalability potential for large-scale qubit readout systems due to its compact design and low power consumption of only 1 uW, making it suitable for integration on the 10 mK stage of a dilution refrigerator. The tunnel diode oscillator exhibits superior amplitude stability compared to commercial microwave sources. The output frequency is centered around 140 MHz, commonly used for qubit readout of electrons in semiconductors, with a frequency tunability of 10 MHz achieved using a varactor diode. Furthermore, the phase noise was significantly improved by replacing the commercially available voltage source with a lead-acid battery, achieving a measured phase noise of -115 dBc/Hz at a 1 MHz offset.