Temperature Dependence of Fidelity for Parametrically Stimulated Gates

Tunability and coherence are the desired properties of an ideal quantum computer. However, introducing tunability directly in the qubit often adversely affects its coherence. This tunability-coherence tradeoff can be optimized by using fixed frequency qubits coupled with a tunable coupler. This architecture has been widely used for demonstrating parametrically stimulated entangling gates. In previous theoretical studies of superconducting circuits, the coupler has always been assumed to be in the ground state and an examination of the temperature dependence of parametric gates has been lacking. Here we present the importance of thermalization of the tunable coupler, to the base temperature of a dilution refrigerator, for achieving a high-fidelity parametric gate. This talk is based on the work presented in "Suppression of Qubit Crosstalk in a Tunable Coupling Superconducting Circuit" (arXiv:1810.04182 [quant-ph])