ARC Centre of Excellence for Engineered Quantum Systems, The University of Queensland, St Lucia, Queensland 4072, Australia.
School of Mathematics and Physics, University of Queensland, Brisbane, Queensland 4072, Australia.
Phys Rev Lett. 2019 Oct 11;123(15):150501. doi: 10.1103/PhysRevLett.123.150501.
We propose and experimentally realize a technique to measure the transfer function of a control line in the frequency domain using a qubit as a vector network analyzer. Our method requires coupling the line under test to the longitudinal component of the Hamiltonian of the qubit and the ability to induce Rabi oscillations through simultaneous driving of the transverse component. The method can be used to increase the fidelity of entangling gates in a quantum processor. We have demonstrated that by characterizing the "flux" control line of a superconducting transmon qubit in the range from 1 to 450 MHz and using this characterization to improve the fidelity of an entangling cphase gate between two transmon qubits.
我们提出并实验实现了一种使用qubit 作为矢量网络分析仪在频域中测量控制线传递函数的技术。我们的方法要求将被测线路与 qubit 的哈密顿量的纵向分量耦合，并通过同时驱动横向分量来诱导拉比振荡。该方法可用于提高量子处理器中纠缠门的保真度。我们已经证明，通过在 1 到 450 MHz 的范围内对超导transmon qubit 的“通量”控制线进行特征描述，并使用这种特征描述来提高两个 transmon qubit 之间的纠缠 cphase 门的保真度。
