CAREER: Quantum Measurements for Optical Communications

光通信能够实现远距离的高速率信息传输。然而，可以传递的信息量从根本上受到用作信息载体的光态的固有量子噪声的限制。这种噪声使任何测量都无法完全区分不同的状态，并产生解码错误。该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检测的特性来最大限度地提高测量灵敏度和增强信息传输，并将开发克服实际通信通道的噪声、损耗和缺陷的方法。这些非常规测量原则上可以提供比当前传统技术可能提供的灵敏度更高的灵敏度，并可用于提高光通信中的信息传输速率。该项目位于光学、通信和量子信息的交汇点，将为本科生和研究生的培养提供理想的环境。该项目的教育计划将为新墨西哥大学(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。这些新的实验将使物理学和光学的本科生和研究生受益，包括少数族裔学生。实验指南将在网上提供，供学生和教师在联尼特派团内外使用。用于区分非正交相干相位态的量子测量可以达到超出量子噪声极限(QNL)的灵敏度，量子噪声极限对应于理想相干(高斯)测量的最终极限，并可用于接近信息传输的最终量子极限。这个项目的目标是研究和实验演示基于非高斯运算的测量的新能力，用于区分量子和经典通信中的非正交相干态。这些测量利用光子计数、位移操作和优化的自适应测量来提高在任意输入功率电平下区分多个状态的灵敏度，同时在现实噪声和通信信道丢失的情况下具有健壮性。这些优化的方法可以用于提高通信中的信息传输速度，实验的目标是展示容量超过使用相干态的高斯测量所能实现的测量。这项工作将使实现QNL以外的灵敏度的优化测量成为一种更现实的替代方案，以增强信息传输，而不是传统通信技术所能实现的。

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.