论文标题
从输入飞行值转移到有损量子记忆的最佳量子转移
Optimal Quantum Transfer from Input Flying Qubit to Lossy Quantum Memory
论文作者
论文摘要
在量子网络中，一个关键的挑战是将飞行盘的直接反射最小化，因为它们将它们融合到基于谐振器基于谐振器的存储器量子位，因为反射振幅代表无法直接恢复的状态转移不忠行为。可以通过将谐振器的耦合率与飞行Qubit场的动态变化来实现优化传输保真度。在这里，我们使用开放的量子系统方法在存在量子存储器的固有损失的情况下分析得出最佳耦合率曲线，该方法可以解释固有的谐振器损失。我们表明，由于谐振器字段必须最初为空，因此必须生成谐振器中的初始振幅，以通过破坏性干扰取消反射；此外，我们表明，这种初始幅度可以使得足够小，以使整个转移过程中的净不忠行为接近统一。然后，我们得出随时间变化的谐振器耦合，该耦合最大化状态转移的保真度是初始种群的函数和内在损耗率的函数，从而为飞行Qubit和谐振器零件之间的最佳量子态转移提供了完整的协议。我们介绍了使用指数和高斯概况的完整协议的保真度的分析表达式和数值示例。我们表明，对于用作量子记忆的谐振器的实际固有损失，可以达到国家转移的保真度约为99.9％。
In a quantum network, a key challenge is to minimize the direct reflection of flying qubits as they couple to stationary, resonator-based memory qubits, as the reflected amplitude represents state transfer infidelity that cannot be directly recovered. Optimizing the transfer fidelity can be accomplished by dynamically varying the resonator's coupling rate to the flying qubit field. Here, we analytically derive the optimal coupling rate profile in the presence of intrinsic loss of the quantum memory using an open quantum systems method that can account for intrinsic resonator losses. We show that, since the resonator field must be initially empty, an initial amplitude in the resonator must be generated in order to cancel reflections via destructive interference; moreover, we show that this initial amplitude can be made sufficiently small as to allow the net infidelity throughout the complete transfer process to be close to unity. We then derive the time-varying resonator coupling that maximizes the state transfer fidelity as a function of the initial population and intrinsic loss rate, providing a complete protocol for optimal quantum state transfer between the flying qubit and resonator qubit. We present analytical expressions and numerical examples of the fidelities for the complete protocol using exponential and Gaussian profiles. We show that a state transfer fidelity of around 99.9% can be reached for practical intrinsic losses of resonators used as quantum memories.
