Black-box optimization of quantum gates for two coupled transmons

As qubit coherence time sets a limit on the total time available for performing quantum gates, realizing high-fidelity, fast quantum gates is critical for enabling long-depth quantum circuits in the non-fault-tolerant regime and represents a path way towards fault tolerant quantum computation. Here, we present simulated and experimental results on using black-box optimization to tune up quantum gates for two transmon qubits coupled via a bus cavity. This optimization procedure does not require any knowledge of gradients derived from the system Hamiltonian, and thus it is ideal for automatic gate optimization on large quantum systems.