Optimized Binary Projectors onto Continuous-Variable non-Gaussian States

Efficient processing and detection of optical signals is central to modern optical technologies ranging from optical communications and precision sensing to emerging photonic quantum technologies. When information is encoded in a quantum system, the measurement used to read out that information must be carefully designed to retrieve it as efficiently as possible. Moreover, this measurement must be optimized for the specific optical quantum state and the information processing task at hand. This project seeks to demonstrate high-fidelity measurements for optical quantum states comprising of superpositions of coherent states based on photon counting measurements and coherent optical processing. Optimized projections onto coherent state superpositions and efficient measurements for distinguish non-orthogonal quantum states can become a new tool for optical quantum information processing and computing. The project will contribute to the development of next-generation photonic quantum technologies that are relevant to academic and industry efforts, and will provide training to graduate and undergraduate students in diverse areas including optics and photonics, metrology, and quantum information science. Optimized quantum measurements allow for extracting information about the properties of quantum states in the most efficient way, and optimize quantum information protocols for computation, communication, and sensing. The proposed project will demonstrate quantum measurements for complex quantum states consisting of coherent state superpositions. These measurements use photon counting and optimized displacement operations to realize complex measurements onto state superpositions with fidelities and sensitivities for state projection and discrimination beyond the reach of standard Gaussian measurements, including homodyne and heterodyne. Experimental demonstrations will use photon number resolving detection and fast optical processing to extend dynamic range and optimize measurement fidelities. This research will advance our understanding of the power of photon counting as a non-Gaussian resource for realizing complex quantum measurements for multiphoton quantum states. Theoretical work will focus on the development of optimized measurement strategies for coherent state superpositions based on photon counting and optimized coherent displacements. Experimental efforts will focus on tabletop demonstrations of these strategies. 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.