Towards High-Fidelity Gates in the Soft Zero-Pi Qubit*

The zero-pi qubit [1, 2] is intrinsically protected against relaxation and dephasing, making it a promising candidate for high-fidelity quantum processing. A recent implementation of the “soft” zero-pi circuit showed experimental evidence of protection and achieved logical operations via a Raman transition [3]. Here, we address some outstanding challenges facing the soft zero-pi qubit. For example, we achieve faster gates via a fast-flux drive through an inductively-coupled bias line. The improvements we made allow for longer coherence times and higher fidelity gates.

[1] A. Kitaev. arXiv:cond-mat/0609441 (2006).
[2] P. Brooks, A. Kitaev, J. Preskill. Phys. Rev. A 87, 052306 (2013).
[3] A. Gyenis, P. Mundada, A. Di Paolo et. al. arXiv:1910.07542 (2019).