论文标题
从连续量子测量和反馈的纠缠限制周期
Entanglement-Preserving Limit Cycles from Sequential Quantum Measurements and Feedback
论文作者
论文摘要
纠缠产生和保存是量子信息处理的关键任务，并且存在各种协议，可以通过测量其自发排放来纠缠远程量子。我们在这里提出反馈方法，基于监视两个量子位的荧光，并仅使用局部Pi-pulses来控制，以增加纠缠两头状态的产量和/或寿命。具体而言，我们描述了一种基于自发发射的照相检测（即使用量子跳跃轨迹）的协议，该方案允许通过测量撤消纠缠纠缠，从而在铃铛状态周围产生限制周期。然后，我们证明，基于同源性测量（即使用扩散量子轨迹），可以对最近的反馈方案进行类似的修改，[L。。 S. Martin和K. B. Whaley，Arxiv：1912.00067]，以增加其创造的纠缠的寿命。我们的方案对于高测量效率最有效，并且量化了不理想的测量效率的影响。我们在这里描述的方法以一种新颖的方式结合了验证的技术，补充了现有协议，并提供了生成和保护纠缠状态的途径，以便它们可以按需用于各种应用。
Entanglement generation and preservation is a key task in quantum information processing, and a variety of protocols exist to entangle remote qubits via measurement of their spontaneous emission. We here propose feedback methods, based on monitoring the fluorescence of two qubits and using only local pi-pulses for control, to increase the yield and/or lifetime of entangled two-qubit states. Specifically, we describe a protocol based on photodetection of spontaneous emission (i.e. using quantum jump trajectories) which allows for entanglement preservation via measurement undoing, creating a limit cycle around a Bell states. We then demonstrate that a similar modification can be made to a recent feedback scheme based on homodyne measurement (i.e. using diffusive quantum trajectories), [L. S. Martin and K. B. Whaley, arXiv:1912.00067] in order to increase the lifetime of the entanglement it creates. Our schemes are most effective for high measurement efficiencies, and the impact of less-than-ideal measurement efficiency is quantified. The method we describe here combines proven techniques in a novel way, complementing existing protocols, and offering a pathway towards generating and protecting entangled states so that they may be used in various applications on demand.
