Analysis of the time-energy entanglement of down-converted photon pairs by correlated single-photon interference
Analysis of the time-energy entanglement of down-converted photon pairs by correlated single-photon interference
复制标题
通过相关单光子干涉分析下转换光子对的时间-能量纠缠
DOI：
10.1103/physreva.86.043823
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发表时间：
2012
影响因子：
2.9
通讯作者：
H. F. Hofmann
中科院分区：
文献类型：
--
作者：
C. Ren;H. F. Hofmann
下转换光子对的时间-能量纠缠特别难以表征，因为光子到达时间的直接测量受到光子探测时间分辨率的限制。在这里，我们探索了用弱相干光的单光子干涉来表征双光子波函数的时间相干性的另一种可能性。具体地说，该方法利用了下转换产生真空态和双光子态的相干叠加这一事实，使得弱相干光干涉后的光子对的符合计数率由下转换产生的双光子波函数与弱相干参考定义的积波函数的叠加给出。通过观察频率相关的干涉模式，可以在单光子干涉中使用的参考脉冲带宽内重建双光子波函数的幅值和相位。因此，相关的单光子干涉提供了下转换过程中产生的纠缠双光子波函数的直接映射。
The time-energy entanglement of down-converted photon pairs is particularly difficult to characterize because direct measurements of photon arrival times are limited by the temporal resolution of photon detection. Here, we explore an alternative possibility of characterizing the temporal coherence of two-photon wave functions using single-photon interference with weak coherent light. Specifically, this method makes use of the fact that down conversion generates a coherent superposition of vacuum and two-photon states, so that the coincidence count rates for photon pairs after interference with weak coherent light are given by a superposition of the two-photon wave function from the down conversion with the product wave function defined by the weak coherent references. By observing the frequency-dependent interference pattern, it is possible to reconstruct the amplitudes and the phases of the two-photon wave function within the bandwidth of the reference pulses used in the single-photon interferences. The correlated single-photon interferences therefore provide a direct map of the entangled two-photon wave function generated in the down-conversion process.