Fast operations, an easily tunable Hamiltonian, and a straightforward two-qubit interaction make charge qubits a useful tool for benchmarking device performance and exploring two-qubit dynamics. Here, we tune a linear chain of four Si/SiGe quantum dots to host two double dot charge qubits. Using the capacitance between the double dots to mediate a strong two-qubit interaction, we simultaneously drive coherent transitions to generate correlations between the qubits. We then sequentially pulse the qubits to drive one qubit conditionally on the state of the other. We find that a conditional π-rotation can be driven in just 74 ps with a modest fidelity demonstrating the possibility of two-qubit operations with a 13.5 GHz clockspeed.

快速的运算，易于调节的哈密顿量以及直接的两个量子位相互作用使电荷量子位成为基准器件性能和探索两个量子位动态的有用工具。在这里，我们调整四个Si / SiGe量子点的线性链，以容纳两个双点电荷量子位。利用双点之间的电容来介导强烈的两个量子位相互作用，我们同时驱动相干跃迁以生成量子位之间的相关性。然后，我们依次对量子位进行脉冲处理，以有条件地驱动一个量子位。我们发现有条件的π旋转可以在74 ps内以适度的保真度驱动，这证明了在13.5 GHz时钟速度下进行两个量子比特操作的可能性。