Analytical controls for dispersive multi-qubit interactions in mediator-coupled quantum registers
Abstract
Fast control of long-lived quantum registers often relies on an auxiliary degree of freedom, a mediator, but real mediator excitation can introduce decoherence, leakage, or loss when the mediator is not the coherence-optimized component. We introduce dispersive interaction via analytical linear inversion (DIAL), an analytical control construction for excitation-suppressed interaction engineering in mediator-coupled quantum registers. In the dispersive regime, we show that off-resonant driving of an effective two-level mediator transition yields a diagonal Hamiltonian whose Pauli-Z interaction rates depend linearly on the drive intensities through a transfer matrix determined by the register-resolved transition spectrum. This establishes a direct linear map from experimentally accessible controls to induced multi-qubit interactions, enabling control design without iterative propagation of the full driven dynamics. We turn this structure into the target-aware DIAL algorithm, which selects favorable off-resonant tones and determines their drive intensities for a prescribed target interaction. We benchmark the resulting controls across 100 register realizations for each register size n=2,3,4,5, targeting the highest-order interaction Z1⋯ Zn with an interaction phase of magnitude π/4, which generates an n-qubit GHZ state up to local equivalence. Propagation under the full driven mediator-register dynamics yields typical gate fidelities above 0.997, while the maximum transient mediator excitation remains near 1% on average, far below what is typically possible with resonant Rabi drives. The manuscript is accompanied by an open-source Python package implementing the target-aware DIAL algorithm and the associated numerical validation workflow.
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BibTeX
@misc{baran2026analytical,
title = {{Analytical controls for dispersive multi-qubit interactions in mediator-coupled quantum registers}},
author = {Bora Baran and Tommaso Calarco and James O'Sullivan and Matthias M. Müller and Felix Motzoi},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.03064},
eprint = {2610.03064},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.03064},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Analytical controls for dispersive multi-qubit interactions in mediator-coupled quantum registers
AU - Bora Baran
AU - Tommaso Calarco
AU - James O'Sullivan
AU - Matthias M. Müller
AU - Felix Motzoi
PY - 2026
DA - 2026/10/02
PB - arXiv
DO - 10.48550/arxiv.2610.03064
UR - https://arxiv.org/abs/2610.03064
AB - Fast control of long-lived quantum registers often relies on an auxiliary degree of freedom, a mediator, but real mediator excitation can introduce decoherence, leakage, or loss when the mediator is not the coherence-optimized component. We introduce dispersive interaction via analytical linear inversion (DIAL), an analytical control construction for excitation-suppressed interaction engineering in mediator-coupled quantum registers. In the dispersive regime, we show that off-resonant driving of an effective two-level mediator transition yields a diagonal Hamiltonian whose Pauli-Z interaction rates depend linearly on the drive intensities through a transfer matrix determined by the register-resolved transition spectrum. This establishes a direct linear map from experimentally accessible controls to induced multi-qubit interactions, enabling control design without iterative propagation of the full driven dynamics. We turn this structure into the target-aware DIAL algorithm, which selects favorable off-resonant tones and determines their drive intensities for a prescribed target interaction. We benchmark the resulting controls across 100 register realizations for each register size n=2,3,4,5, targeting the highest-order interaction Z_1⋯ Z_n with an interaction phase of magnitude π/4, which generates an n-qubit GHZ state up to local equivalence. Propagation under the full driven mediator-register dynamics yields typical gate fidelities above 0.997, while the maximum transient mediator excitation remains near 1% on average, far below what is typically possible with resonant Rabi drives. The manuscript is accompanied by an open-source Python package implementing the target-aware DIAL algorithm and the associated numerical validation workflow.
ER -