Title: Radio-frequency reflectometry in bilayer graphene devices utilizing micro graphite back-gates Show Chinese title

Title: 利用微石墨背栅的双层石墨烯器件中的射频反射测量

Abstract: Bilayer graphene is an attractive material that realizes high-quality two-dimensional electron gas with a controllable bandgap. By utilizing the bandgap, electrical gate tuning of the carrier is possible and formation of nanostructures such as quantum dots have been reported. To probe the dynamics of the electronics states and realize applications for quantum bit devices, RF-reflectometry which enables high-speed electric measurements is important. Here we demonstrate RF-reflectometry in bilayer graphene devices. We utilize a micro graphite back-gate and an undoped Si substrate to reduce the parasitic capacitance which degrades the RF-reflectometry. We measure the resonance properties of a tank circuit which contains the bilayer graphene device. We form RF-reflectmetory setup and compared the result with the DC measurement, and confirmed their consistency. We also measure Coulomb diamonds of quantum dots possibly formed by bubbles and confirm that RF-reflectometry of quantum dots can be performed. This technique enables high-speed measurements of bilayer graphene quantum dots and contributes to the research of bilayer graphene-based quantum devices by fast readout of the states. Show Chinese abstract

Abstract: 双层石墨烯是一种吸引人的材料，能够实现高质量的二维电子气，并具有可调带隙。 通过利用带隙，可以实现载流子的电门调控，并已报道了如量子点等纳米结构的形成。 为了探测电子态的动力学并实现量子比特器件的应用，能够进行高速电信号测量的射频反射测量非常重要。 在此我们展示了在双层石墨烯器件中的射频反射测量。 我们使用微米石墨背栅和无掺杂的硅基板以减少影响射频反射测量的寄生电容。 我们测量了包含双层石墨烯器件的谐振电路的共振特性。 我们建立了射频反射测量装置，并将结果与直流测量进行了比较，确认了它们的一致性。 我们还测量了可能由气泡形成的量子点的库仑钻石，并确认可以对量子点进行射频反射测量。 该技术使得能够对双层石墨烯量子点进行高速测量，并通过快速读取状态促进了基于双层石墨烯的量子器件的研究。