Escape of a Driven Quantum Josephson Circuit into Unconfined States
Raphaël Lescanne, Lucas Verney, Quentin Ficheux, Michel H. Devoret, Benjamin Huard, Mazyar Mirrahimi, Zaki Leghtas · Physical Review Applied · 2019
Strongly driven superconducting Josephson circuits are instrumental in emulating a variety of Hamiltonians that are useful for quantum information processing. However, such a time-dependent, nonlinear, open quantum system can display complex dynamics that lead to degradation of coherence times, instabilities, and chaotic behavior. Here the authors observe an instability that results in the escape of a circuit's mode into states that are not confined by the Josephson cosine potential. This work guides us toward circuit designs that prevent instabilities, and thus are suitable for parametric pumping and quantum information processing.