Four-mode quantum sensing and Fisher information in a spin-orbit-coupled Bose gas

• Main Authors: Zhu, Fei, Tang, Zheng, Zeng, Liang, Wang, Shu, Chen, Li
• Format: Journal Article
• Language: English
• Published: 06.08.2025
• Subjects: Physics - Quantum Gases; Physics - Quantum Physics
• DOI: 10.48550/arxiv.2508.04140

Multi-mode squeezing and entanglement are important resources in quantum metrology and sensing. For spin-1/2 Bose-Einstein condensates subject to spin-orbit coupling (SOC), previous studies on spin squeezing have been limited to two-mode systems. In this work, we demonstrate that such a system can naturally construct a four-mode model spanning an $\mathfrak{su}(4)$ algebra with six SU(2) subspaces. Using spin squeezing parameters and quantum Fisher information matrices, we analyze the dynamical evolution of coherent spin states. The results show that, beyond two-mode models, the SOC-induced four-mode couplings give rise to richer entanglement-enhanced sensing approaching the Heisenberg limit across various SU(2) subspaces. Additionally, by tuning a single system parameter (the Raman Rabi frequency), one can selectively control the optimal measurement directions across different subspaces.