二维量子阱中单电子量子比特的性质

通过求解能量本征方程,得到弱磁场作用下的二维势阱中电子的本征能量及其波函数,进而以基态和第一激发态波函数构造了一个量子比特.数值计算结果表明,量子比特内电子的空间概率密度随空间坐标和时间的变化而变化,在阱的边缘处出现的概率值为零,在其他位置相对较大;各个空间点的概率密度均随时间做周期振荡,振荡周期与阱宽有关,与外磁场无关,它随阱宽的增加而增大.     

Semiconductor quantum computation

Semiconductors, a significant type of material in the information era, are becoming more and more powerful in the field of quantum information. In recent decades, semiconductor quantum computation was investigated thoroughly across the world and developed with a dramatically fast speed. The research varied from initialization, control and readout of qubits, to the architecture of fault-tolerant quantum computing. Here, we first introduce the basic ideas for quantum computing, and then discuss the developments of single- and two-qubit gate control in semiconductors. Up to now, the qubit initialization, control and readout can be realized with relatively high fidelity and a programmable two-qubit quantum processor has even been demonstrated. However, to further improve the qubit quality and scale it up, there are still some challenges to resolve such as the improvement of the readout method, material development and scalable designs. We discuss these issues and introduce the forefronts of progress. Finally, considering the positive trend of the research on semiconductor quantum devices and recent theoretical work on the applications of quantum computation, we anticipate that semiconductor quantum computation may develop fast and will have a huge impact on our lives in the near future.     

Swap量子门的消相干特性

利用单电子量子点的自旋态,研究了Swap量子门的量子相干特性。得到了系统的超算子,并利用超算子得出了体系的密度矩阵元,在玻恩和马尔科夫近似下,分析了体系由于磁环境所引起的消相干特性。     

微波驱动超导量子比特产生Greenberger-Horne-Zeilenger态

提出一个基于超导量子比特系统,利用微波驱动交叉共振技术制备GHZ态的方案。本方案操控比传统方案更简单,量子比特始终处于最佳工作点,不需要额外的磁通来调节跃迁频率,避免了频谱拥挤,延长了相干时间。