Analytical controls for dispersive multi-qubit interactions in mediator-coupled quantum registers
Year: 2026
Type: preprint
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 \(Z_1\cdots Z_n\) 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.
Source: arXiv (Cornell University)
Institutions: Forschungszentrum Jülich, University of Cologne
Language: English
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Awards: Robust superconducting and hybrid quantum bits, Programmable Atomic Large-scale Quantum Simulation 2 - SGA1, G3022749744, Spin based quantum computer and simulator (SPINUS), G3731544974, G3948410504, G3976037732, G4432934295, G5442384851, Open Superconducting Quantum Computers (OpenSuperQPlus), G6405278853, G6971144659, Quantum Computational Fluid Dynamics, G8308332008, G8959349008
OpenAlex ID: W7220383597