Noise modeling of trimon superconducting circuits*

Superconducting circuits have emerged as promising platforms for enabling multimode interactions in quantum systems. Composite qubit circuits allow for multiple strongly-coupled qubit modes in a single circuit. A notable instance of these circuits is the trimon, characterized by its all-to-all (virtual) qubit ZZ couplings. Despite the unique capabilities of trimons, the noise environment within such multimode systems remains largely unexplored. We study the noise characteristics and explore symmetries within the trimon's noise environment, starting from a circuit-level description. Gaining insights into these noise dynamics can help harness the trimon's distinct features for quantum error correction or error suppression techniques. Our work broadens the knowledge of composite qubit circuit noise dynamics and paves the way toward enhanced performance of multimode quantum circuits.