Hitachi Cambridge Laboratory, J. J. Thomson Avenue, Cambridge CB3 0HE, UK.
CEA, LETI, Minatec Campus, F-38054 Grenoble, France.
Nat Commun. 2015 Jan 20;6:6084. doi: 10.1038/ncomms7084.
Quantum computation requires a qubit-specific measurement capability to readout the final state of individual qubits. Promising solid-state architectures use external readout electrometers but these can be replaced by a more compact readout element, an in situ gate sensor. Gate-sensing couples the qubit to a resonant circuit via a gate and probes the qubit's radiofrequency polarizability. Here we investigate the ultimate performance of such a resonant readout scheme and the noise sources that limit its operation. We find a charge sensitivity of 37 μe Hz(-1/2), the best value reported for this technique, using the example of a gate sensor strongly coupled to a double quantum dot at the corner states of a silicon nanowire transistor. We discuss the experimental factors limiting gate detection and highlight ways to optimize its sensitivity. In total, resonant gate-based readout has advantages over external electrometers both in terms of reduction of circuit elements as well as absolute charge sensitivity.
量子计算需要一种特定于量子位的测量能力来读取单个量子位的最终状态。有前途的固态架构使用外部读出静电计，但这些可以被更紧凑的读出元件，即原位栅极传感器所取代。栅极感应通过栅极将量子位与谐振电路耦合，并探测量子位的射频极化率。在这里，我们研究了这种谐振读出方案的极限性能以及限制其操作的噪声源。我们使用硅纳米线晶体管角态上的强耦合双量子点的栅极传感器的例子，发现了 37μeHz(-1/2)的电荷灵敏度，这是该技术的最佳值。我们讨论了限制栅极检测的实验因素，并强调了优化其灵敏度的方法。总的来说，基于谐振的栅极读出在减少电路元件以及绝对电荷灵敏度方面都优于外部静电计。
