2026/07/30 by Marta Cagetti, Stefan Forstner, Victor Champain +8
Physics and Astronomy · #cond-mat.mes-hall
arxiv created 2026/07/30 · arxiv updated 2026/07/31
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~μe/√(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~μs, without any false assignments over 107 measurements and a signal-to-noise ratio of 17 exceeding the state of the art.