文献类型：期刊文献

英文题名：Tunable higher-order spectral splitting and enhanced sensing around a second-order exceptional point

作者：Sheng, Tianze[1,2];Zhang, Lida[2,3];Niu, Yueping[1,2,3];Gong, Shangqing[1,2,3,4]

机构：[1]East China Univ Sci & Technol, Sch Mat Sci & Engn, Shanghai 200237, Peoples R China;[2]East China Univ Sci & Technol, Sch Phys, Shanghai 200237, Peoples R China;[3]Shanghai Frontiers Sci Ctr Optogenet Tech Cell Met, Shanghai 200237, Peoples R China;[4]Hefei Natl Lab, Hefei 230088, Anhui, Peoples R China

年份：2026

卷号：114

期号：1

外文期刊名：PHYSICAL REVIEW A

收录：;WOS:【SCI-EXPANDED(收录号:WOS:001833649400007)】；

基金：This work was supported by the National Natural Sci-ence Foundation of China (Grants No. 12034007 and No. 12374327) , Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0300802) , Major Project of Shanghai Municipal Education Commission (Grant No. 2023ZKZD39) , and Program of Shanghai Academic Research Leader (Grant No. 21XD1400700) .

语种：英文

摘要：It is intuitively believed that the eigenvalues of a physical system and the corresponding spectral splitting of the output spectrum respond similarly to perturbations, for instance, both scale as root E in the vicinity of a secondorder exceptional point (EP2), where E denotes the perturbation. Here we challenge this conventional view by demonstrating that the spectral splitting can be tuned to scale as 4 root Eor6 root E around an EP2 in a nonlinear quantum system consisting of two coupled cavity squeezing processes. When measuring E based on the spectral splitting, we further show that the corresponding measurement sensitivity can be enhanced by orders of magnitude below the standard quantum limit (SQL) owing to the combined effect of sublinear signal response and suppressed quantum noise. Our findings fundamentally reshape the understanding of the relation between the eigenvalues and spectral splitting in response to perturbations and also open alternative avenues for EP-based sensing with noise suppression below the SQL.