Quantum-state tomography of single-photon entangled states
Quantum-state tomography of single-photon entangled states
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DOI：
10.1103/physreva.92.032328
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发表时间：
2015-09-28
影响因子：
2.9
通讯作者：
Beck, M.
中科院分区：
文献类型：
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作者：
Burch, E. T.;Henelsmith, C.;Beck, M.
我们已经对几种不同的单光子纠缠态进行了量子态断层扫描，即在两个可能的路径之间共享单个光子的状态。我们首先对子空间中的密度矩阵进行层析成像重建，其中单个光子由两种空间模式共享。在这个子空间中，我们能够创建高保真、路径纠缠的状态。同样在这个子空间中，我们使用 Akaike 信息准则和蒙特卡罗模拟来帮助我们估计系统中状态漂移的数量和来源。我们发现初级态漂移是由于我们的实验装置中的相位漂移和 pi/400 数量级的波动造成的。然后，我们使用单光子子空间密度矩阵和进一步的测量来估计更大空间中的密度矩阵，该空间由两种模式组成，每种模式最多包含一个光子。在这个更大的空间中，我们发现密度矩阵的并发性为 C 同余于 0.08，并且比 0 至少大 45 个标准差，这表明我们的状态确实是纠缠的。
We have performed quantum-state tomography on several different single-photon entangled states, that is, states in which a single photon is shared between two possible paths. We begin by doing a tomographic reconstruction of density matrices in the subspace where a single photon is shared by two spatial modes. In this subspace we are able to create high-fidelity, path-entangled states. Also within this subspace we use the Akaike information criterion and Monte Carlo simulations to help us estimate the amount and source of state drift in our system. We find that the primary state drift is due to phase drifts and fluctuations on the order of pi/400 in our experimental apparatus. We then use the single-photon subspace density matrices and further measurements to estimate density matrices in the larger space consisting of two modes containing up to one photon each. In this larger space we find that the concurrence of the density matrices is C congruent to 0.08 and is greater than 0 by at least 45 standard deviations, indicating that our states are indeed entangled.