CAREER: Quantum Measurements for Optical Communications

光通信能够在长距离上实现高速率的信息传输。然而，可以传递的信息量从根本上受到用作信息载体的光的状态的固有量子噪声的限制。这种噪声妨碍了任何测量完美地区分不同的状态，并产生解码错误。本项目将研究和实验演示激光等光的相干态的非常规测量，利用相干态和单光子探测的特性，最大限度地提高测量灵敏度和增强信息传输，并将开发克服真实的通信信道的噪声、损耗和缺陷的方法。这些非常规测量原则上可以提供超出当前常规技术可能的灵敏度，并且可以用于增加光通信中的信息传输速率。该项目位于光学、通信和量子信息的接口，将为本科生和研究生的教育提供理想的环境。该项目的教育计划将为新墨西哥州大学（UNM）的实验室课程开发新的实验，以加强本科生和研究生课程。这些新的实验将有利于物理学和光学专业的本科生和研究生，包括代表性不足的少数民族学生。实验室指南将在线提供给UNM内外的学生和教师使用。用于非正交相干相位状态的鉴别的量子测量可以实现超出量子噪声极限（QNL）的灵敏度，该极限对应于理想相干（高斯）测量的极限，并且可以用于接近信息传输的最终量子极限。该项目的目标是研究和实验证明基于非高斯操作的测量的新能力，用于在量子和经典通信中应用的非正交相干态的鉴别。这些测量利用光子计数，位移操作和优化的自适应测量，以提高在任意输入功率水平的多个状态的歧视的灵敏度，同时在现实的噪声和通信信道的损失下是鲁棒的。这些优化的方法可以应用于提高通信中的信息传输速率，实验的目的是证明测量的能力超出了使用相干态的高斯测量所能达到的能力。这项工作将使优化的测量实现超越QNL的灵敏度，一个更现实的替代方案，以加强信息传输超越传统的通信技术可以实现的。

Optical communication enables high rates of information transfer over long distances. However, the amount of information that can be communicated is fundamentally limited by the intrinsic quantum noise of the states of light used as information carriers. This noise precludes any measurement from perfectly distinguishing different states and generates decoding errors. This project will investigate and experimentally demonstrate non-conventional measurements for coherent states of light, such as laser light, that exploit the properties of coherent states and single-photon detection to maximize the measurement sensitivity and enhance information transfer, and will develop methods to overcome noise, loss, and imperfections of real communication channels. These non-conventional measurements can in principle provide sensitivities beyond what is possible with current conventional technologies, and can be used to increase the rate of information transfer in optical communication. This project lies at the interface of optics, communication, and quantum information, and will provide an ideal environment for education of undergraduate and graduate students. The educational plan of the project will develop new experiments for laboratory courses at the University of New Mexico (UNM) that will strengthen the undergraduate and graduate curriculum. These new experiments will benefit undergraduate and graduate students in physics and optics including underrepresented minority students. Lab guides will be available online for use by students and instructors within and outside UNM.Quantum measurements for the discrimination of non-orthogonal coherent phase states can achieve sensitivities beyond the quantum noise limit (QNL), which corresponds to the ultimate limit for ideal coherent (Gaussian) measurements, and can be used to approach the ultimate quantum limits of information transfer. The goal of this project is to investigate and experimentally demonstrate new capabilities of measurements based on non-Gaussian operations for the discrimination of non-orthogonal coherent states for applications in quantum and classical communications. These measurements utilize photon counting, displacement operations and optimized adaptive measurements to enhance sensitivities for the discrimination of multiple states at arbitrary input power levels while being robust under realistic noise and loss of communication channels. These optimized methods can be applied to enhance the rate of information transfer in communications, and experiments will aim to demonstrate measurements with capacities beyond what is achievable with Gaussian measurements using coherent states. This work will make optimized measurements achieving sensitivities beyond the QNL a more realistic alternative to enhance information transfer beyond what can be achieved with conventional communication technologies.