High-order orbital angular momentum modes in bright squeezed vacuum states of light

螺旋相位光束由于其轨道角动量吸引了越来越多的兴趣。的（几乎）无限值导致基态范围不受限制，即所谓的轨道角动量模式，这可能使更大的字母量子密钥分发成为可能，并提供抗窃听的高维量子信息。轨道角动量模式在远距离传输信息、设计新型成像系统和增强量子密码方面非常有前途。此外，轨道角动量模式可用于高分辨率和高灵敏度的测量以及通过光-物质相互作用对粒子进行光学操纵。为了进一步提高轨道角动量模式的量子容量，可以使用每个模式具有巨大光子数的量子光。一个很有希望的候选者是明亮的压缩真空。明亮压缩真空是一种宏观的非经典光态，可以通过高增益参数下转换或四波混频获得，具有非常宽的光子数分布和非常高的光子数。与位移的压缩光态不同，明亮的压缩真空只由量子噪声组成，并且具有很强的光子数相关性，导致噪声降低到短噪声水平以下，并导致正交压缩。明亮压缩真空的这些特性使其在量子成像和敏感计量、量子光力学、引力波探测、量子光非线性光学等各种应用中具有很大的吸引力。本文的工作重点是对明亮压缩真空中迄今尚未探索的高阶轨道角动量模式的物理性质的理论描述、它们的制备和分类。所有这些模式的制备和分类方案都将基于二晶和三晶结构，并使用额外的光学元件和非高斯泵浦光束。从施密特模式的角度对所选择的轨道角动量模式进行描述。提出了高正交压缩单轨道角动量模和光子数相关轨道角动量模对的制备方法，并将噪声降至短噪声级以下。同时，我们计划提出和计算应用高阶轨道角动量模式的方案，用于机械物体的旋转和传递从光子系统到机械子系统的强相关性，用于测试原子、分子、量子点的非对称吸收光谱，用于测试不同物体的手性，以及用于非常敏感的相位测量。在此基础上，建立了包含时间顺序效应的明亮压缩真空中轨道角动量模的理论描述。

Helically-phased light beams attract more and more interest due to the orbital angular momentum that they carry. The (almost) unlimited value of leads to an unrestricted range of basis states, so-called orbital angular momentum modes, which may enable larger-alphabet quantum key distribution and provide high-dimensional quantum information resistant to eavesdropping. Orbital angular momentum modes are very promising for transmitting information over large distances, designing novel imaging systems and empowering quantum cryptography opportunities. Moreover, orbital angular momentum modes can be used in high-resolution and high-sensitivity measurements and for the optical manipulation of particles through light-matter interaction. To improve the quantum capacity of orbital angular momentum modes even further, one could use quantum light with huge photon numbers per mode. A promising candidate for that is the bright squeezed vacuum. Bright squeezed vacuum, is a macroscopic non-classical state of light that can be obtained via high-gain parametric-down-conversion or four-wave-mixing, and has a very broad photon-number distribution with very high photon numbers. Unlike displaced squeezed-light states, bright squeezed vacuum consists only of quantum noise and has strong photon-number correlations, leading to the reduction of noise below the shot-noise level as well as to quadrature squeezing. Such features of bright squeezed vacuum make it very attractive for various applications such as quantum imaging and sensitive metrology, quantum optomechanics, gravitational wave detecting, and nonlinear optics with quantum light. The proposed work focuses on the theoretical description of physical properties of so far unexplored high-order orbital angular momentum modes in bright squeezed vacuum, their preparation and sorting. All schemes for preparation and sorting of such modes will be based on the two- and three-crystal configuration with using an additional optical elements and non-Gaussian pump beams. The description of the selected orbital angular momentum modes will be performed from the point of view of Schmidt modes. The methods for preparation of a single orbital angular momentum mode with high quadrature squeezing and photon-number-correlated pairs of orbital angular momentum modes with noise reduction below the shot-noise level will be suggested. Simultaneously, we plan to suggest and calculate schemes of applying high-order orbital angular momentum modes for the rotation of mechanical objects and for passing strong correlations from the light subsystem to the mechanical one, for testing non-symmetrical absorption spectra of atoms, molecules, quantum dots, for testing the chirality of different objects, and for very sensitive phase measurements. Moreover, a theoretical description of orbital angular momentum modes in bright squeezed vacuum including time-ordering effects will be developed.