Title: Dark-state solution and symmetries of the two-qubit multimode asymmetric quantum Rabi model Show Chinese title

Title: 暗态解和两量子比特多模非对称量子Rabi模型的对称性

Abstract: We study the two-qubit asymmetric quantum Rabi model (AQRM) and find its dark-state solution. Such solutions have at most one photon and constant eigenenergy in the whole coupling regime, causing level crossings in the spectrum, although there is no explicit conserved quantity except energy. We find an operator in the eigenenergy basis to label all the degeneracies with its eigenvalues, and compare it with the well-known hidden symmetry which exists when bias parameter $\epsilon$ is a multiple of half of the resonator frequency $\omega$. Extended to the multimode case, we find symmetries related with conserved bosonic number operators, which also cause level crossings. This provides a perspective for symmetry studies on generalized Rabi models. Show Chinese abstract

Abstract: 我们研究了两量子比特非对称量子Rabi模型（AQRM），并找到了它的暗态解。 这些解在全部耦合范围内最多包含一个光子且本征能量恒定，尽管除了能量外没有显式的守恒量，但会导致能谱中的能级交叉。 我们发现了一个在本征能量基底下定义的算符，用其本征值来标记所有的简并，并将其与当偏置参数$\epsilon$为谐振器频率$\omega$的一半的整数倍时存在的已知隐藏对称性进行比较。 扩展到多模情况，我们发现了与守恒的玻色子数算符相关的对称性，这些对称性也会导致能级交叉。 这为对广义Rabi模型的对称性研究提供了一个新的视角。