标题： 通过自适应同态检测确定性制备真空加一个光子的叠加态：实验考虑因素 显示英文标题

标题： Deterministic preparation of superpositions of vacuum plus one photon by adaptive homodyne detection: experimental considerations

摘要： 光学量子比特的制备阶段是所有用于测试和展示量子光学原理的实验设置中的关键任务。 我们考虑一种确定性协议，用于制备真空态和单光子数态的叠加态，该协议的优势在于通过使用本地振荡器的相位敏感测量（'dyne检测'）来减少所需的资源量。 我们研究了使用不同相位测量方案的协议性能：同频检测、外差检测和自适应dyne检测（涉及反馈环路）。 首先，我们为制备的态定义了一个合适的性能指标，并根据所考虑的相位测量得到了该指标的解析表达式。 此外，我们研究了相位测量可能表现出的限制，例如反馈策略中的延迟或资源有限。 最后，我们评估了在实验设置中方便可用的不同模式形状下的协议性能指标。 我们表明，即使在存在这些限制的情况下，简单的反馈算法也能表现得非常出色，优于当仅采用简单的同频检测或外差检测方案时的协议。 显示英文摘要

摘要： The preparation stage of optical qubits is an essential task in all the experimental setups employed for the test and demonstration of Quantum Optics principles. We consider a deterministic protocol for the preparation of qubits as a superposition of vacuum and one photon number states, which has the advantage to reduce the amount of resources required via phase-sensitive measurements using a local oscillator ('dyne detection'). We investigate the performances of the protocol using different phase measurement schemes: homodyne, heterodyne, and adaptive dyne detection (involving a feedback loop). First, we define a suitable figure of merit for the prepared state and we obtain an analytical expression for that in terms of the phase measurement considered. Further, we study limitations that the phase measurement can exhibit, such as delay or limited resources in the feedback strategy. Finally, we evaluate the figure of merit of the protocol for different mode-shapes handily available in an experimental setup. We show that even in the presence of such limitations simple feedback algorithms can perform surprisingly well, outperforming the protocols when simple homodyne or heterodyne schemes are employed.