Cancellation of unwanted ZZ interactions by superconducting qubit engineering*

We present a method to cancel the unwanted always-on ZZ interaction in transmon based qubit architectures by qubit engineering. We employ a new engineered qubit, which operates as a weakly anharmonic oscillator and has anharmonicity comparable to the transmon qubit, but with a positive sign. We test this concept on the cross-resonance-gate architecture [1] and outline various strategies for optimal chip design. Based on that, we design a new architecture for a superconducting quantum processor that has an inherent suppression of the unwanted ZZ interactions. Our work addresses on one of the major challenges in a commonly used architecture for superconducting quantum processors, and it enables higher fidelity multiqubit gates.

[1] Chow, J. M. et al. Phys. Rev. Lett. 107, 080502 (2011).