Current-based RF charge sensing in a carbon nanotube

Marta Cagetti; Stefan Forstner; Victor Champain; Roger Tormo-Queralt; Christoffer B. Møller; Sergio L. De Bonis; Chandan Samanta; Elsa Vázquez-Rodriguez; Eneko Mateos-Madinabeitia; David A. Czaplewski; Adrian Bachtold

arXiv · 2607.28313

Current-based RF charge sensing in a carbon nanotube

Marta Cagetti·Stefan Forstner·Victor Champain·Roger Tormo-Queralt·Christoffer B. Møller·Sergio L. De Bonis·Chandan Samanta·Elsa Vázquez-Rodriguez·Eneko Mateos-Madinabeitia·David A. Czaplewski·Adrian Bachtold

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Abstract

Ultra-sensitive charge detection is a widely used tool for quantum electronics with applications in quantum information processing and in probing the physics of condensed matter systems. Existing approaches require either an impedance-matched resonant circuit, or millimeter-scale proximity between amplifier and sample, both adding complexity and constraining device design. In this work, we introduce a current-mode charge sensor in a suspended carbon nanotube, operating at the $1.25$ MHz resonance of an RLC tank circuit and achieving a charge sensitivity of $0.15~\mu e/\sqrt{\mathrm{Hz}}$. We utilize it to measure a double quantum dot (DQD) electrostatically defined in the same nanotube, revealing a highly regular charge stability diagram. We perform single-shot readout of the DQD charge state at an integration time of $3.56~\mu\mathrm{s}$, without any false assignments over $10^{7}$ measurements and a signal-to-noise ratio of 17 exceeding the state of the art.

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Marta Cagetti, Stefan Forstner, Victor Champain, Roger Tormo-Queralt, Christoffer B. Møller, Sergio L. De Bonis, Chandan Samanta, Elsa Vázquez-Rodriguez, Eneko Mateos-Madinabeitia, David A. Czaplewski, Adrian Bachtold. 2026-07-30. Current-based RF charge sensing in a carbon nanotube. https://arxiv.org/abs/2607.28313

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