Fukui Kosuke, Takeda Shuntaro, Endo Mamoru, Asavanant Warit, Yoshikawa Jun-Ichi, van Loock Peter, Furusawa Akira
Department of Applied Physics, School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan.
Institute of Physics, Johannes Gutenberg-Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany.
Phys Rev Lett. 2022 Jun 17;128(24):240503. doi: 10.1103/PhysRevLett.128.240503.
Non-Gaussian states are essential for many optical quantum technologies. The so-called optical quantum state synthesizer (OQSS), consisting of Gaussian input states, linear optics, and photon-number resolving detectors, is a promising method for non-Gaussian state preparation. However, an inevitable and crucial problem is the complexity of the numerical simulation of the state preparation on a classical computer. This problem makes it very challenging to generate important non-Gaussian states required for advanced quantum information processing. Thus, an efficient method to design OQSS circuits is highly desirable. To circumvent the problem, we offer a scheme employing a backcasting approach, where the circuit of OQSS is divided into some sublayers, and we simulate the OQSS backwards from final to first layers. Moreover, our results show that the detected photon number by each detector is at most 2, which can significantly reduce the requirements for the photon-number resolving detector. By virtue of the potential for the preparation of a wide variety of non-Gaussian states, the proposed OQSS can be a key ingredient in general optical quantum information processing.
非高斯态对于许多光学量子技术至关重要。所谓的光学量子态合成器（OQSS）由高斯输入态、线性光学元件和光子数分辨探测器组成，是制备非高斯态的一种很有前景的方法。然而，一个不可避免且至关重要的问题是在经典计算机上对态制备进行数值模拟的复杂性。这个问题使得生成先进量子信息处理所需的重要非高斯态极具挑战性。因此，非常需要一种设计OQSS电路的有效方法。为规避该问题，我们提供了一种采用回溯方法的方案，其中OQSS电路被划分为一些子层，并且我们从最后一层到第一层对OQSS进行反向模拟。此外，我们的结果表明每个探测器检测到的光子数最多为2，这可以显著降低对光子数分辨探测器的要求。凭借制备各种非高斯态的潜力，所提出的OQSS可以成为一般光学量子信息处理的关键要素。
