Realization of adiabatic and diabatic CZ gates in superconducting qubits coupled with a tunable coupler*
Huikai Xu, Weiyang Liu, Zhiyuan Li, Jiaxiu Han, Jing-Ning Zhang, Kehuan Linghu, Yongchao Li, Mo Chen, Zhen Yang, Junhua Wang, Teng Ma, Guangming Xue, Yirong Jin, Haifeng Yu
Abstract
High fidelity two-qubit gates are fundamental for scaling up the superconducting qubit number. We use two qubits coupled via a frequency-tunable coupler which can adjust the coupling strength, and demonstrate the CZ gate using two different schemes, adiabatic and diabatic methods. The Clifford based randomized benchmarking (RB) method is used to assess and optimize the CZ gate fidelity. The fidelities of adiabatic and diabatic CZ gates are 99.53(8)% and 98.72(2)%, respectively. We also analyze the errors induced by the decoherence. Comparing to 30 ns duration time of adiabatic CZ gate, the duration time of diabatic CZ gate is 19 ns, revealing lower incoherence error rate <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msub> <mml:msup> <mml:mi>r</mml:mi> <mml:mo>′</mml:mo> </mml:msup> <mml:mrow> <mml:mi mathvariant="normal">incoherent</mml:mi> <mml:mo>,</mml:mo> <mml:mi mathvariant="normal">int</mml:mi> </mml:mrow> </mml:msub> <mml:mo>=</mml:mo> <mml:mn>0.0197</mml:mn> <mml:mo stretchy="false">(</mml:mo> <mml:mn>5</mml:mn> <mml:mo stretchy="false">)</mml:mo> </mml:mrow> </mml:math> compared to r incoherent, int = 0.0223(3).