Designing quantum gates for superconducting qubits with tunable couplers*

Selecting the architecture of a superconducting quantum processor requires making many design choices, sometimes trying to meet conflicting demands. In this talk, I will discuss the architecture we have developed for our processors in the Wallenberg Centre for Quantum Technology. I will show how we use tunable couplers between fixed-frequency transmon qubits to realize various two- and three-qubit gates based on parametric modulation of the couplers [1,2,3], and how the frequencies of the qubits are chosen to avoid crosstalk between such gates in a square lattice containing several tens, or more, qubits [4]. I will also discuss how we can both mitigate and use ZZ coupling between the qubits in this setup [5], as well as quantify the impact of decoherence for all gates in a simple way [6,7].

[1] Kosen et al., Quantum Sci. Technol. 7, 035018 (2022)

[2] Gu et al., PRX Quantum 2, 040348 (2021)

[3] Warren et al., npj Quantum Inf. 9, 44 (2023)

[4] Osman et al., Phys. Rev. Res. 5, 043001 (2023)

[5] Pettersson Fors et al., in preparation

[6] Abad et al., Phys. Rev. Lett. 129, 150504 (2022)

[7] Abad et al., arXiv:2302.13885