Quantum Measurements for Continuous-Variable States with Photon Counting

光场状态的测量是物理和工程领域许多技术应用的中心，包括光通信、传感和计量以及信息处理。当光学状态编码信息时，最佳或接近最佳的测量允许有效且可靠地解码该信息，从而增强通信和信息处理中不同协议的性能。测量的设计和优化关键取决于光学状态的固有性质和要实现的测量中的可用资源。该项目将基于光子计数测量和优化的相干位移操作，研究由相干态（来自激光器的光）和态叠加组成的光学态的最佳和接近最佳的量子测量。对相干态及其叠加态的优化测量可以为全光量子信息处理和长距离量子通信协议提供新的工具。此外，设计有效的量子测量光学量子态是必不可少的光子量子技术，这是许多学术界和工业界的努力在世界范围内的主题的当前和未来的发展。量子测量理论提供了一个基本的理解的限制可实现的灵敏度确定量子系统的状态。该项目将展示用于量子通信，信息处理和计算应用的相干态及其叠加的优化量子测量。这些优化的测量是基于光子计数，相干位移操作和自适应测量，这将允许设计各种各样的优化量子测量的不同状态和测量问题。所提出的相干态的量子测量寻求实现复杂的投影和非投影测量，其具有超出包括高斯测量（零差/外差）的标准测量范例所能达到的状态投影和辨别的灵敏度和灵敏度。该项目将通过开发高保真度超灵敏光学测量的实验技术，以及通过设计和优化有限资源的复杂量子测量的理论方法，推进新知识。理论上的努力将集中在量子测量的相干态及其叠加的基础上光子计数，相干位移，和自适应策略。实验工作将集中在桌面实验中对这些策略的演示上。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

Measurement of the state of an optical field is at the center of many technological applications across physics and engineering including optical communications, sensing and metrology, and information processing. When the optical state encodes information, optimal or near optimal measurements allow for decoding this information efficiently and reliably, enhancing the performance of different protocols in communications and information processing. The design and optimization of measurements critically depend on the intrinsic properties of the optical states and the available resources in the measurement to be realized. This project will investigate optimal and near optimal quantum measurements for optical states comprised of coherent states (light from lasers) and state superpositions, based on photon counting measurements and optimized coherent displacement operations. Optimized measurements for coherent states and their superpositions can provide a new tool for protocols in all-optical quantum information processing and long-distance quantum communications. Furthermore, the design of efficient quantum measurements for optical quantum states is essential for current and future developments in photonic quantum technologies, which are the subject of many academic and industrial efforts worldwide.Quantum measurement theory provides a fundamental understanding of the limits on the achievable sensitivity for determining the states of quantum systems. This project will demonstrate optimized quantum measurements for coherent states and their superpositions for applications in quantum communications, information processing, and computation. These optimized measurements are based on photon counting, coherent displacement operations, and adaptive measurements, which will allow for the design of a wide class of optimized quantum measurements for diverse states and measurement problems. The proposed quantum measurements of coherent states seek to realize complex projective and non-projective measurements with fidelities and sensitivities for state projection and discrimination beyond the reach of standard measurement paradigms including Gaussian measurements (homodyne/heterodyne). The project will advance new knowledge through the development of experimental techniques for ultrasensitive optical measurements with high fidelity, and through theoretical methods for the design and optimization of complex quantum measurements with finite resources. Theoretical efforts will focus on quantum measurements of coherent states and their superpositions based on photon counting, coherent displacements, and adaptive strategies. Experimental efforts will focus on the demonstrations of these strategies in tabletop experiments.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.