论文标题
Wigner函数断层扫描通过光学参数扩增
Wigner Function Tomography via Optical Parametric Amplification
论文作者
论文摘要
Wigner函数断层扫描对于表征量子状态是必不可少的，但是其常用的版本平衡的同伴检测，遭受了几个弱点。首先，它需要有效的检测，这对于测量脆弱的非高斯州，尤其是明亮的状态至关重要。其次，它需要一个局部振荡器，该振荡器量身定制以匹配正在测试的状态的时空特性，并且对于多模和宽带状态而言失败。在这里，我们建议基于光学参数扩增的Wigner函数断层扫描，然后直接检测。该方法不受检测效率低下和损失的影响，适用于宽带，在空间和时间上多模量子状态。为了证明原则，我们通过实验重建了挤压真空的Wigner功能，该功能占据了强数模态的单个模式。我们获得了$ -7.5 \ pm 0.4 $ db的压缩，纯度为$ 0.91^{+0.09} _ { - 0.08} $，尽管主要由过滤造成的$ 97 \％$ $损失。从理论上讲，我们还考虑了挤压单个光子的重建 - 一个明亮的非高斯状态。由于强大的多模参数扩增，该方法允许多种模式同时进行断层扫描。这使其成为光学量子信息处理的强大工具。
Wigner function tomography is indispensable for characterizing quantum states, but its commonly used version, balanced homodyne detection, suffers from several weaknesses. First, it requires efficient detection, which is critical for measuring fragile non-Gaussian states, especially bright ones. Second, it needs a local oscillator, tailored to match the spatiotemporal properties of the state under test, and fails for multimode and broadband states. Here we propose Wigner function tomography based on optical parametric amplification followed by direct detection. The method is immune to detection inefficiency and loss, and suitable for broadband, spatially and temporally multimode quantum states. To prove the principle, we experimentally reconstruct the Wigner function of squeezed vacuum occupying a single mode of a strongly multimode state. We obtain a squeezing of $-7.5\pm 0.4$ dB and a purity of $0.91^{+0.09}_{-0.08}$ despite more than $97\%$ loss caused mainly by filtering. Theoretically, we also consider the reconstruction of a squeezed single photon - a bright non-Gaussian state. Due to strong multimode parametric amplification, the method allows for the simultaneous tomography of multiple modes. This makes it a powerful tool for optical quantum information processing.
