Bosonic quantum control with a weakly coupled fluxonium qubit
Abstract
Echoed Conditional Displacement (ECD) gates constitute a fundamental building block for quantum control of harmonic oscillator modes. However, bit-flips of the auxiliary qubit remain a dominant error mechanism for this kind of bosonic control. In this work, we present a numerical case study of a bit-flip protected fluxonium operating as the control qubit and numerically implement ECD gates in a single-mode resonator-fluxonium device, demonstrating that fidelities exceeding 99.9% are possible. We systematically investigate the resonator dynamics using a combination of semiclassical trajectories and master equation simulations, numerically revealing asymptotic saturation of the dispersive shift in the strongly driven regime of the resonator. We develop an efficient technique to numerically simulate the strongly driven regime of the resonator using a semiclassical formulation that maps the full perturbation series in the dispersive expansion as order-by-order frequency shifts. This provides a compact polynomial description of the resonator which is intuitive and remains valid throughout the dispersive regime. Furthermore, we propose an improved ECD sequence that accounts for the effects of photon loss and spurious nonlinear terms on resonator trajectories.
Related
- Bosonic Error Correction with Fluxonium
- Tensor-network simulation of strongly coupled multi-fluxonium circuits
- Optimal Control of a Fluxonium Circuit with the Q-PRONTO Numerical Method
- Symmetry Control in Coupled Quantum Cascade Ring Lasers
- Mitigating Capacitive Loading Enables Fast Two-Qubit Gates in Highly Connected Fluxonium Quantum Processors
BibTeX
@misc{ali2026bosonic,
title = {{Bosonic quantum control with a weakly coupled fluxonium qubit}},
author = {Anaida Ali and Shantanu R. Jha and Shoumik D. Chowdhury and Lev-Arcady Sellem and Max Hays and William D. Oliver and Baptiste Royer},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2609.01817},
eprint = {2609.01817},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2609.01817},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Bosonic quantum control with a weakly coupled fluxonium qubit
AU - Anaida Ali
AU - Shantanu R. Jha
AU - Shoumik D. Chowdhury
AU - Lev-Arcady Sellem
AU - Max Hays
AU - William D. Oliver
AU - Baptiste Royer
PY - 2026
DA - 2026/09/01
PB - arXiv
DO - 10.48550/arxiv.2609.01817
UR - https://arxiv.org/abs/2609.01817
AB - Echoed Conditional Displacement (ECD) gates constitute a fundamental building block for quantum control of harmonic oscillator modes. However, bit-flips of the auxiliary qubit remain a dominant error mechanism for this kind of bosonic control. In this work, we present a numerical case study of a bit-flip protected fluxonium operating as the control qubit and numerically implement ECD gates in a single-mode resonator-fluxonium device, demonstrating that fidelities exceeding 99.9% are possible. We systematically investigate the resonator dynamics using a combination of semiclassical trajectories and master equation simulations, numerically revealing asymptotic saturation of the dispersive shift in the strongly driven regime of the resonator. We develop an efficient technique to numerically simulate the strongly driven regime of the resonator using a semiclassical formulation that maps the full perturbation series in the dispersive expansion as order-by-order frequency shifts. This provides a compact polynomial description of the resonator which is intuitive and remains valid throughout the dispersive regime. Furthermore, we propose an improved ECD sequence that accounts for the effects of photon loss and spurious nonlinear terms on resonator trajectories.
ER -