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arXiv · 2507.09715

Intrinsic Multi-Mode Interference for Passive Suppression of Purcell Decay in Superconducting Circuits

Mustafa Bakr·Mohammed Alghadeer·Simon Pettersson Fors·Simone D. Fasciati·Shuxiang Cao·Atharv Mahajan·Smain Amari·Anton Frisk Kockum·Peter Leek
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Abstract

Decoherence due to radiative decay remains an important consideration in scaling superconducting quantum processors. We introduce a passive, interference-based methodology for suppressing radiative decay using only the intrinsic multi-mode structured environment of superconducting circuits. By taking into account the full electromagnetic mode-mode couplings within the device, we derive analytic conditions that enable destructive interference. These conditions are realized by introducing controlled geometric asymmetries -- such as localized perturbations to the transmon capacitor -- which increase mode hybridization and activate interference between multiple decay pathways. We validate this methodology using perturbation theory, full-wave electromagnetic simulations, and experimental measurements of a symmetry-broken transmon qubit with improved coherence times.

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Mustafa Bakr, Mohammed Alghadeer, Simon Pettersson Fors, Simone D. Fasciati, Shuxiang Cao, Atharv Mahajan, Smain Amari, Anton Frisk Kockum, Peter Leek. 2025-07-13. Intrinsic Multi-Mode Interference for Passive Suppression of Purcell Decay in Superconducting Circuits. https://arxiv.org/abs/2507.09715

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