Kristen M, Schneider A, Stehli A, Wolz T, Danilin S, Ku H S, Long J, Wu X, Lake R, Pappas D P, Ustinov A V, Weides M
Institute of Physics, Karlsruhe Institute of Technology, 76131 Karlsruhe, Germany.
James Watt School of Engineering, University of Glasgow, Glasgow G12 8LT, UK.
npj Quantum Inf. 2020;6(1). doi: 10.1038/s41534-020-00287-w.
Experiments with superconducting circuits require careful calibration of the applied pulses and fields over a large frequency range. This remains an ongoing challenge as commercial semiconductor electronics are not able to probe signals arriving at the chip due to its cryogenic environment. Here, we demonstrate how the on-chip amplitude and frequency of a microwave signal can be inferred from the ac Stark shifts of higher transmon levels. In our time-resolved measurements we employ Ramsey fringes, allowing us to detect the amplitude of the systems transfer function over a range of several hundreds of MHz with an energy sensitivity on the order of 10. Combined with similar measurements for the phase of the transfer function, our sensing method can facilitate pulse correction for high fidelity quantum gates in superconducting circuits. Additionally, the potential to characterize arbitrary microwave fields promotes applications in related areas of research, such as quantum optics or hybrid microwave systems including photonic, mechanical or magnonic subsystems.
超导电路实验需要在很宽的频率范围内对施加的脉冲和场进行仔细校准。由于其低温环境，商用半导体电子设备无法探测到达芯片的信号，这仍然是一个持续存在的挑战。在此，我们展示了如何从更高的跨导量子比特能级的交流斯塔克位移推断微波信号的片上幅度和频率。在我们的时间分辨测量中，我们采用了拉姆齐条纹，这使我们能够在几百兆赫兹的范围内检测系统传递函数的幅度，能量灵敏度约为10。结合对传递函数相位的类似测量，我们的传感方法可以促进超导电路中高保真量子门的脉冲校正。此外，表征任意微波场的潜力推动了在相关研究领域的应用，如量子光学或包括光子、机械或磁子子系统的混合微波系统。
