Clean carbon nanotubes coupled to superconducting impedance-matching circuits

TL;DR

This paper demonstrates a novel mechanical transfer method to couple pristine carbon nanotubes with superconducting microwave circuits, enabling high-bandwidth, low-noise quantum measurements.

Contribution

It introduces a fabrication-compatible technique to integrate low-disorder nanotubes with superconducting resonators, preserving transport properties.

Findings

Successful coupling of nanotubes to superconducting circuits

Retention of quantum dot control and transport characteristics

Potential for high-bandwidth noise correlation measurements

Abstract

Coupling carbon nanotube devices to microwave circuits offers a significant increase in bandwidth and signal-to-noise ratio. These facilitate fast non-invasive readouts important for quantum information processing, shot noise and correlation measurements. However, creation of a device that unites a low-disorder nanotube with a low-loss microwave resonator has so far remained a challenge, due to fabrication incompatibility of one with the other. Employing a mechanical transfer method, we successfully couple a nanotube to a gigahertz superconducting matching circuit and thereby retain pristine transport characteristics such as the control over formation of, and coupling strengths between, the quantum dots. Resonance response to changes in conductance and susceptance further enables quantitative parameter extraction. The achieved near matching is a step forward promising high-bandwidth noise correlation measurements on high impedance devices such as quantum dot circuits.