SAMOP 2023 – scientific programme
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QI: Fachverband Quanteninformation
QI 23: Poster II (joint session QI/Q)
QI 23.11: Poster
Wednesday, March 8, 2023, 16:30–19:00, Empore Lichthof
Optimising gate performance of transmon qubits coupled by a central tunable bus — •Alexander Möller1,2, Matthias G. Krauss2, Daniel Basilewitsch2,3, and Christiane P. Koch2 — 1Technische Universität Berlin, Berlin, Germany — 2Freie Universität Berlin, Berlin, Germany — 3Universität Innsbruck, Innsbruck, Austria
For transmon qubits coupled via a transmission line cavity, optimal control theory (OCT) has identified the quasi-dispersive regime to be optimal for universal quantum computing. For a single control driving the harmonic coupler, both local and entangling gates can be implemented with high fidelity and short gate durations [Goerz et al., npj Quantum Information 3, 37 (2017)]. In an analogous manner we aim at exploring the transmon parameter landscape for a system of two transmons addressed by a third transmon acting as a tunable bus. We investigate how the anharmonicity of this central coupler affects the implemented gates and the OCT optimisation. Here we especially focus on the controllability of the two-transmon-subsystem as well as the achievable gates for different pulse durations and from this determine their respective quantum speed limit. Furthermore, we present an effective analytical model for the coupling between the outer transmons.