Title: Radio frequency single electron transmission spectroscopy of a semiconductor Si/SiGe quantum dot Show Chinese title

Title: 半导体Si/SiGe量子点的射频单电子输运谱

Abstract: Rapid single shot spin readout is a key ingredient for fault tolerant quantum computing with spin qubits. An RF-SET (radio-frequency single electron transistor) is predominantly used as its the readout timescale is far shorter than the spin decoherence time. In this work, we experimentally demonstrate a transmission-based RF-SET using a multi-module semiconductor-superconductor assembly. A monolithically integrated SET placed next to a double quantum dot in a Si/SiGe heterostructure is wire-bonded to a superconducting niobium inductor forming the impedance-transforming network. Compared to RF reflectometry, the proposed set-up is experimentally simpler without the need for directional couplers. Read-out performance is benchmarked by the signal-to-noise (SNR) of a dot-reservoir transition (DRT) and an interdot charge transition (ICT) in the double quantum dot near the SET as a function of RF power and integration time. The minimum integration time for unitary SNR is found to be 100 ns for ICT and 300 ns for DRT. The obtained minimum integration times are comparable to the state of the art in conventional RF reflectometry set-ups. Furthermore, we study the turn-on properties of the RF-SET to investigate capacitive shifts and RF losses. Understanding these effects are crucial for further optimisations of the impedance transforming network as well as the device design to assist RF read-out. This new RF read-out scheme also shows promise for multiplexing spin-qubit readout and further studies on rapid charge dynamics in quantum dots. Show Chinese abstract

Abstract: 单次快速自旋读出是容错量子计算中使用自旋量子比特的关键组成部分。射频单电子晶体管（RF-SET）主要用作读出工具，因为其读出时间尺度远小于自旋退相干时间。在这项工作中，我们实验性地展示了基于传输的RF-SET，该装置由一个多模块半导体-超导体组件构成。一个单片集成的SET被放置在Si/SiGe异质结构中的双量子点旁边，并通过引线键合到超导铌电感器上，形成阻抗变换网络。与射频反射测量相比，所提出的装置在不需要方向耦合器的情况下实验上更为简单。读出性能通过信号噪声比（SNR）来评估，该比值用于测量SET附近的双量子点中的点库过渡（DRT）和量子点间电荷过渡（ICT），作为射频功率和积分时间的函数。发现实现单位SNR所需的最小积分时间对于ICT为100纳秒，对于DRT为300纳秒。获得的最小积分时间与传统射频反射测量设置中的现有技术相当。此外，我们研究了RF-SET的开启特性，以调查电容偏移和射频损耗。理解这些效应对于进一步优化阻抗变换网络以及设备设计以辅助射频读出至关重要。这种新的射频读出方案还显示出在多路复用自旋量子比特读出以及量子点中快速电荷动力学的进一步研究方面的潜力。