Active isolation of transmon readout with a tunable inductive bridge
Abstract
Scalable superconducting quantum computation requires fast, high-fidelity readout. Currently, this is assisted through cryogenic amplification of the readout signal. In traditional dispersive readout schemes, the amplifiers that are used to provide high signal-to-noise ratio also generate thermal noise that can decohere the qubits, demanding additional ferrite-based isolators to suppress this noise. Here, we integrate a chip-scale microwave switch, the tunable inductive bridge, into the readout chain of a fixed-frequency transmon. Flux-pulsing the switch, such that it transmits only during the readout, did not make a discernable difference to qubit coherence, residual excited-state population, or readout fidelity metrics. By injecting broadband noise that mimics amplifier thermal photons, we show that the switch suppresses the resulting qubit dephasing by more than $30$~dB, consistent with its independently measured on-off ratio, establishing it as a potential chip-based integrated replacement for readout-chain isolators.
Related
- Persistent level-resolved transmon population after dispersive readout, and the limits of its open-system description
- Fast CZ gate in hybrid fluxonium-transmon systems with tunable couplers
- Tunable annealing of defects in self-aligning active crystals
- Rhenium as a material platform for long-lived transmon qubits
- Parametrically Driven iSWAP Gate Using a Capacitively Shunted Double-Transmon Coupler at the Zero-Flux Sweet Spot
BibTeX
@misc{ding2026active,
title = {{Active isolation of transmon readout with a tunable inductive bridge}},
author = {Chunyang Ding and Chuyao Tong and Paul Varosy and Nikitha Jain and Ziyi Zhao and Eric I. Rosenthal and Konrad W. Lehnert and David I. Schuster},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.27137},
eprint = {2610.27137},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.27137},
}
RIS
TY - UNPB
TI - Active isolation of transmon readout with a tunable inductive bridge
AU - Chunyang Ding
AU - Chuyao Tong
AU - Paul Varosy
AU - Nikitha Jain
AU - Ziyi Zhao
AU - Eric I. Rosenthal
AU - Konrad W. Lehnert
AU - David I. Schuster
PY - 2026
DA - 2026/10/19
PB - arXiv
DO - 10.48550/arxiv.2610.27137
UR - https://arxiv.org/abs/2610.27137
AB - Scalable superconducting quantum computation requires fast, high-fidelity readout. Currently, this is assisted through cryogenic amplification of the readout signal. In traditional dispersive readout schemes, the amplifiers that are used to provide high signal-to-noise ratio also generate thermal noise that can decohere the qubits, demanding additional ferrite-based isolators to suppress this noise. Here, we integrate a chip-scale microwave switch, the tunable inductive bridge, into the readout chain of a fixed-frequency transmon. Flux-pulsing the switch, such that it transmits only during the readout, did not make a discernable difference to qubit coherence, residual excited-state population, or readout fidelity metrics. By injecting broadband noise that mimics amplifier thermal photons, we show that the switch suppresses the resulting qubit dephasing by more than $30$~dB, consistent with its independently measured on-off ratio, establishing it as a potential chip-based integrated replacement for readout-chain isolators.
ER -