Gate Dispersive Charge Detection in Ge/SiGe Quantum Dots
Abstract
Spin qubits are an attractive platform for scalable quantum computation, and recently, laterally gated quantum dots (QDs) in Ge heterostructures have emerged as a leading implementation. Radio-frequency (RF) single-hole transistor (SHT) spin readout and integrated superconducting resonator charge readout have demonstrated in Ge QDs, but their wiring overhead and on-chip size can pose challenges, while gate dispersive (GD) readout, which requires less on-chip overhead, has yet to be demonstrated for Ge QDs. Here we demonstrate compact, low-overhead RF-GD charge readout of a Ge double QD (DQD), both directly, and assisted by a proximal single-hole box (SHB). We resolve QD loading and interdot transitions with both techniques. We obtain unity signal-to-noise ratio (SNR) in 2.7 millisecond and 135 microsecond integration time, for gate-dispersive detection of the DQD and SHB-DQD systems, respectively. We find that the SHB enhances the interdot signal-to-noise ratio (SNR) of our 540 MHz circuit by a factor of 20 for a DQD coupling tc ≈ 5 GHz. Power and temperature dependent measurements verify that SNR is limited by dielectric loss. We argue that with achievable improvements in dielectric loss and amplification, high-fidelity (99\%) readout in less than 1 microsecond should be possible, assuming ideal spin-to-charge conversion, which has seen rapid recent progress. These results establish a simple and compact gate-based readout approach for direct and SHB-enhanced readout of Ge heterostructure QDs.
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BibTeX
@misc{tanvir2026gate,
title = {{Gate Dispersive Charge Detection in Ge/SiGe Quantum Dots}},
author = {M. R. Tanvir and E. Sajadi and M. Veldhorst and G. Scappucci and J. Salfi},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.01100},
eprint = {2610.01100},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.01100},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Gate Dispersive Charge Detection in Ge/SiGe Quantum Dots
AU - M. R. Tanvir
AU - E. Sajadi
AU - M. Veldhorst
AU - G. Scappucci
AU - J. Salfi
PY - 2026
DA - 2026/10/19
PB - arXiv
DO - 10.48550/arxiv.2610.01100
UR - https://arxiv.org/abs/2610.01100
AB - Spin qubits are an attractive platform for scalable quantum computation, and recently, laterally gated quantum dots (QDs) in Ge heterostructures have emerged as a leading implementation. Radio-frequency (RF) single-hole transistor (SHT) spin readout and integrated superconducting resonator charge readout have demonstrated in Ge QDs, but their wiring overhead and on-chip size can pose challenges, while gate dispersive (GD) readout, which requires less on-chip overhead, has yet to be demonstrated for Ge QDs. Here we demonstrate compact, low-overhead RF-GD charge readout of a Ge double QD (DQD), both directly, and assisted by a proximal single-hole box (SHB). We resolve QD loading and interdot transitions with both techniques. We obtain unity signal-to-noise ratio (SNR) in 2.7 millisecond and 135 microsecond integration time, for gate-dispersive detection of the DQD and SHB-DQD systems, respectively. We find that the SHB enhances the interdot signal-to-noise ratio (SNR) of our 540 MHz circuit by a factor of 20 for a DQD coupling t_c ≈ 5 GHz. Power and temperature dependent measurements verify that SNR is limited by dielectric loss. We argue that with achievable improvements in dielectric loss and amplification, high-fidelity (99\%) readout in less than 1 microsecond should be possible, assuming ideal spin-to-charge conversion, which has seen rapid recent progress. These results establish a simple and compact gate-based readout approach for direct and SHB-enhanced readout of Ge heterostructure QDs.
ER -