AI 中文总结
本研究将非厄米物理与量子非线性结合，通过电路QED系统实现单光子相关非线性过程，优化转换效率，为单光子级量子器件优化提供通用途径。
AI 中文摘要
量子非线性光学旨在利用强光子-光子相互作用实现可扩展量子技术，不过耗散损耗仍是实现近100%转换效率的主要障碍。本研究将非厄米物理与量子非线性领域结合，利用完美吸收识别并优化少光子非线性过程，理论研究了两个工作在光-物质超强耦合区的电路量子电动力学（circuit QED）系统：第一个系统（i）可通过单光子实现同时双原子激发，第二个系统（ii）实现单光子与双光子福克态（Fock states）的强耦合。研究表明，由于强光学非线性在线性响应理论层面就已产生量子谱特征，|S₁₁|中的完美吸收条件可实现近确定性单光子下转换，分别得到（i）量子比特-量子比特关联对和（ii）双光子对；转换效率可通过实验可及参数系统优化，这些参数均与有效非厄米哈密顿量中厄米子空间的出现相关。该研究将非厄米工程确立为单光子级量子器件优化的通用可行途径，适用范围甚至超出电路量子电动力学平台。
英文摘要
Quantum nonlinear optics seeks to harness strong photon-photon interactions for scalable quantum technologies, although dissipative losses still pose a major barrier to near-unity conversion efficiency. Here, we bridge non-Hermitian physics with the quantum nonlinear domain by exploiting perfect absorption to identify and optimize few-photon nonlinear processes. We theoretically investigate two circuit QED systems, operating in the light-matter ultrastrong coupling regime. The first (i) enables simultaneous two-atom excitations by single photons, while the second (ii) realizes the strong coupling between a single-photon and a two-photon Fock states. We demonstrate that, since the strong optical nonlinearities cause quantum spectral features to emerge already at the level of linear response theory, the perfect absorption condition in $|S_{11}|$ enables near-deterministic single-photon down-conversion into (i) a qubit-qubit-correlated pair and (ii) a two-photon pair. We show that the conversion efficiency can be systematically optimized through experimentally accessible parameters, both linked to the emergence of Hermitian subspaces within the effective non-Hermitian Hamiltonians. These findings position non-Hermitian engineering as a broadly applicable route to optimizing quantum devices at the single-photon level, even beyond circuit-QED platforms.
Comments26 pages, 13 figures
