Two-qubit gates with high accuracy are one of the most important elements in implementing fault tolerant quantum computer. Currently, in a system using a superconducting quantum circuit, a charge qubit called transmon[1] is mainly used, and its fabrication is relatively easy, and a coherence time exceeding 100 us has been reported[2]. One of the main ways to perform a two-qubit gate using the transmons is tuning the transition frequency of the transmon by SQUID[3], and the other is irradiating microwave pulses[4]. When the transmon frequency is tunable, the coherence time is decreased due to the influence of the low frequency noise[5], and in the frequency fixed system, the static ZZ interaction due to the small anharmonicity of the transmon limits the fidelity of the two qubit gate. In order to solve these problems, a pulse sequence with dynamical decoupling[4] and a tunable couplers[6] have been proposed.
In this presetation, we describe the results of theoretical analysis of a new method for reducing Qubit crosstalk (static ZZ interactions) without introducing complex pulse sequence and magnetic flux degrees of freedom.

[1] Jens Koch et al. , Phys. Rev. A 76, 042319 (2007)
[2] Alex P. M. Place et al. , Arxiv 2003.00024 (2020)
[3] Rami Barends et al. , Nature, 508(7497), 500-503 (2014)
[4] Sarah Sheldon et al. , Phys. Rev. A 93, 060302 (2016)
[5] F. Yoshihara et al. , Phys. Rev. Lett. 97, 167001 (2006)
[6] Pranav Mundada et al. , Phys. Rev. App 12, 054023 (2019)

Keyword1           superconducting circuit
Keyword2           quantum information
Keyword3           superconducting qubit