Quantum State Tomography of Qudits via Hong-Ou-Mandel Interference
Quantum State Tomography of Qudits via Hong-Ou-Mandel Interference
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DOI：
10.1103/physrevapplied.19.014008
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发表时间：
2022-05
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影响因子：
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通讯作者：
Yoshiaki Tsujimoto;R. Ikuta;K. Wakui;Toshiki Kobayashi;M. Fujiwara
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作者：
Yoshiaki Tsujimoto;R. Ikuta;K. Wakui;Toshiki Kobayashi;M. Fujiwara
Hong-Ou-Mandel（HOM）干涉[1]是一种基于光子玻色子性质的聚束现象。当使用半分束器（HBS）将两个完全无法区分的光子混合时，它们总是聚束并表现出不重合，从而导致称为HOM dip的特定干涉图。HOM干涉的重要性质是重合度的降低反映了输入光子的不可分辨性的程度，即，它提供关于输入光子的重叠概率的信息。因此，该属性应该能够使用已知状态下的探测光子来估计未知量子状态下的目标光子。在这项工作中，我们实现了上述概念的量子态层析（QST）适用于$d\text{-dimensional}$光子qudits，我们称之为HOM-QST [2]。有趣的是，我们观察到HOM-QST对各种缺陷是鲁棒的，并且探测光子可以被经典光取代。此外，我们证实了这一点，通过演示使用二维偏振量子比特的原理验证实验。
Hong-Ou-Mandel (HOM) interference [1] is a bunching phenomenon based on the bosonic nature of photons. When two photons that are perfectly indistinguishable from each other are mixed using a half beam splitter (HBS), they always bunch and exhibit the absence of coincidence resulting in a specific interferogram called HOM dip. The important property of the HOM interference is that the decrease in coincidence reflects the degree of indistinguishability of the input photons, i.e., it provides information regarding the probability of overlap of the input photons. Thus, this property should enable the estimation of a target photon in an unknown quantum state using a probe photon in a known state. In this work, we realize the above concept as the quantum state tomography (QST) applicable to $d\text{-dimensional}$ photonic qudits, which we call HOM-QST [2]. Interestingly, we observe that HOM-QST is robust against various imperfections and that the probe photon can be replaced by classical light. Furthermore, we confirm this by demonstrating a proof-of-principle experiment using two-dimensional polarization qubits.