van Diepen Cornelis J, Hsiao Tzu-Kan, Mukhopadhyay Uditendu, Reichl Christian, Wegscheider Werner, Vandersypen Lieven M K
QuTech and Kavli Institute of Nanoscience, Delft University of Technology, 2600, GA, Delft, The Netherlands.
Solid State Physics Laboratory, ETH Zürich, 8093, Zürich, Switzerland.
Nat Commun. 2021 Jan 4;12(1):77. doi: 10.1038/s41467-020-20388-6.
The spin of a single electron in a semiconductor quantum dot provides a well-controlled and long-lived qubit implementation. The electron charge in turn allows control of the position of individual electrons in a quantum dot array, and enables charge sensors to probe the charge configuration. Here we show that the Coulomb repulsion allows an initial charge transition to induce subsequent charge transitions, inducing a cascade of electron hops, like toppling dominoes. A cascade can transmit information along a quantum dot array over a distance that extends by far the effect of the direct Coulomb repulsion. We demonstrate that a cascade of electrons can be combined with Pauli spin blockade to read out distant spins and show results with potential for high fidelity using a remote charge sensor in a quadruple quantum dot device. We implement and analyse several operating modes for cascades and analyse their scaling behaviour. We also discuss the application of cascade-based spin readout to densely-packed two-dimensional quantum dot arrays with charge sensors placed at the periphery. The high connectivity of such arrays greatly improves the capabilities of quantum dot systems for quantum computation and simulation.
半导体量子点中单个电子的自旋提供了一种可控且寿命长的量子比特实现方式。电子电荷进而允许控制量子点阵列中单个电子的位置，并使电荷传感器能够探测电荷配置。在此我们表明，库仑排斥力允许初始电荷跃迁诱导后续电荷跃迁，引发一连串的电子跳跃，就像推倒多米诺骨牌一样。级联可以沿着量子点阵列传输信息，传输距离远远超出直接库仑排斥力的影响范围。我们证明，一连串电子可以与泡利自旋阻塞相结合，以读出远距离的自旋，并使用四量子点器件中的远程电荷传感器展示出具有高保真潜力的结果。我们实现并分析了级联的几种操作模式，并分析了它们的缩放行为。我们还讨论了基于级联的自旋读出在周边放置电荷传感器的密集二维量子点阵列中的应用。这种阵列的高连通性极大地提高了量子点系统用于量子计算和模拟的能力。
