ExpandQISE: Track 1: Exceptional entanglement transition and supersensitive quantum sensing empowered by anti-Hermiticity and symmetries

Non-technical Abstract: As an emerging interdisciplinary research area, Quantum Information Science and Engineering (QISE) is poised to revolutionize computing, communication, signal processing, networks, metrology, sensing, and more. However, despite notable progress in this field, the decoherence of quantum states inevitably introduces imperfections and errors in quantum operations. In this project, the team aims to tackle this challenge by harnessing non-Hermitian physics, along with non-Hermiticity and symmetries, to preserve and enhance nonclassical correlations and entanglement properties in two complementary open quantum systems with groundbreaking theoretical and experimental demonstrations. These advancements can have exemplary applications in supersensitive quantum sensing. Moreover, the study of these two systems unveils new insights into the distinct characteristics of non-Hermitian quantum physics, which fundamentally differ from classical or Hermitian physics. This project also prioritizes student training, particularly focusing on those from underrepresented minorities, thereby strengthening the pipeline that supplies the science and engineering workforce in QISE. Outreach activities, such as public lectures and high school quantum summer research internships, cater to high-school students and the general public, thus fostering broader engagement with quantum science and technology. Technical Abstract: Integrated quantum photonics and superconducting circuits are emerging as two primary contenders for various QISE tasks. However, their quantum performance is highly susceptible to decoherence. The current mainstream QISE research focuses on controlling and mitigating various decoherence factors to preserve the coherence of quantum states, yet, significant challenges persist. In this project, the team exploits the effects of anti-Hermiticity and symmetries such as parity-time symmetry, and their induced nontrivial phase transitions. First-of-its-kind testbeds, which link twin beams or two coupled qubits with phase-sensitive amplification or natural dissipation, will be developed. These testbeds enable studies on quadrature and quantum-mechanical passive parity-time symmetries, respectively. The project emphasizes the non-Hermitian evolution of quantum systems with nonclassical correlations and entanglement, exploring their intricate and even counterintuitive connections with non-Hermiticity and symmetries. Furthermore, this project explores the potential applications of these systems in supersensitive quantum sensing. The successful outcomes of this proposal will deepen our understanding of the fundamental roles of gain and loss in symmetry-underlying physics and their implications in open quantum systems. Additionally, it will provide experimental insights into several open questions that are currently subject to focused debate. Moreover, the exotic quantum photonic processing, based on continuous variables and discrete variables, under quadrature and passive parity-time symmetries, can offer elegant solutions to key challenges that are insurmountable using existing Hermitian methodologies. While the current experimental research is limited to demonstrating a few fundamental quantum effects, developed systems and techniques from this groundbreaking research can be deployed to a wide range of continuous-variables- and discretized-variables-based QISE studies. This project is jointly funded by the Office of Multidisciplinary Activities (MPS/OMA), and the Technology Frontiers Program (TIP/TF). 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.