Regensburg 2025 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 55: Superconducting Electronics: SQUIDs, Qubits, Circuit QED III
TT 55.7: Talk
Friday, March 21, 2025, 11:00–11:15, H36
Suppressing chaos with mixed superconducting qubit devices — •Ben Blain1,2, Giampiero Marchegiani1, Luigi Amico1,3,4, and Gianluigi Catelani5,1 — 1Quantum Research Center, Technology Innovation Institute, Abu Dhabi 9639, UAE — 2School of Physics and Astronomy, University of Kent, Canterbury CT2 7NH, United Kingdom — 3Dipartimento di Fisica e Astronomia, Via S. Sofia 64, 95123 Catania, Italy — 4INFN-Sezione di Catania, Via S. Sofia 64, 95127 Catania, Italy — 5JARA Institute for Quantum Information (PGI-11),Forschungszentrum Jülich, 52425 Jülich, Germany
In quantum information processing, a tension between two different tasks occurs: while qubits’ states can be preserved by isolating them, quantum gates can be realized only through qubit-qubit interactions. In arrays of qubits, weak coupling leads to states being spatially localized and strong coupling to delocalized states. Here, we study the average energy level spacing and the relative entropy of the distribution of the level spacings to analyze the crossover between localized and delocalized (chaotic) regimes in linear arrays of superconducting qubits. We consider both transmons as well as capacitively shunted flux qubits, which enables us to tune the qubit anharmonicity. Arrays with uniform anharmonicity display remarkably similar dependencies of level statistics on the coupling strength. In systems with alternating anharmonicity, the localized regime is found to be more resilient to the increase in qubit-qubit coupling strength in comparison to arrays with a single qubit type. This result supports designing devices that incorporate different qubit types to achieve higher performances.
Keywords: Transmon; Flux qubit; Chaos; Localization; Level statistics