论文标题
关于量子相干反馈网络的动力学，腔介导的双量子点量子
On the dynamics of a quantum coherent feedback network of cavity-mediated double quantum dot qubits
论文作者
论文摘要
本文的目的是对相干反馈网络进行全面研究，其中主要组件由两个直接耦合与腔的两个远程双量子点（DQD）量子组组成。该主要成分最近已被物理实现（van Woerkom，{\ it等}，半导体矩形之间的微波光子光子介导的相互作用，物理评论x，8（4）：041018，2018）。反馈循环通过用梁插曲器级联级联来封闭。从三个角度研究了这个连贯的反馈网络的动态。首先，得出了由单光子状态驱动的网络的输出单光子状态的分析形式。特别是，观察到相干反馈会大大延长输入单光子与网络之间的相互作用。其次，当网络由单光子输入状态驱动时，计算DQD量子位的激发概率。此外，如果输入是真空的，但是两个DQD量子位之一是以其激发态初始化的，则尤其是得出网络状态的明确表达，并且表明，如果两个DQD Qubit的过渡频率相等，则表明输出场和两个DQD量子器可以形成一个串联状态。最后，获得脉冲形状的确切形式，可以通过该形式在任何可控时间都可以完全激发这两个DQD量子位之一，这在构建$ 2 $ qubit-qubit的量子门中可能很有用。
The purpose of this paper is to present a comprehensive study of a coherent feedback network where the main component consists of two distant double quantum dot (DQD) qubits which are directly coupled to a cavity. This main component has recently been physically realized (van Woerkom, {\it et al.}, Microwave photon-mediated interactions between semiconductor qubits, Physical Review X, 8(4):041018, 2018). The feedback loop is closed by cascading this main component with a beamsplitter. The dynamics of this coherent feedback network is studied from three perspectives. First, an analytic form of the output single-photon state of the network driven by a single-photon state is derived; in particular, it is observed that coherent feedback elongates considerably the interaction between the input single photon and the network. Second, excitation probabilities of DQD qubits are computed when the network is driven by a single-photon input state. Moreover, if the input is vacuum but one of the two DQD qubits is initialized in its excited state, the explicit expression of the state of the network is derived, in particular, it is shown that the output field and the two DQD qubits can form an entangled state if the transition frequencies of two DQD qubits are equal. Finally, the exact form of the pulse shape is obtained by which the single-photon input can fully excite one of these two DQD qubits at any controllable time, which may be useful in the construction of $2$-qubit quantum gates.
