[@Dimer], and trapped ions [@Cirac]. Recently, the spin-boson model has been realized by the ultrastrong coupling of a superconducting flux qubit to an open one-dimensional (1D) transmission line  [@Forn2]. The counterrotating terms can be strongly suppressed in some proposed schemes [AnistropicDicke,Keeling,Fanheng]{}. In some systems, the anisotropy appears quite naturally, because they are controlled by different input parameters  [@Grimsmo1]. On the theoretical side, the anisotropic models where the rotating and counterrotating terms are different have attracted considerable attentions. Rich quantum phase transitions (QPTs) in the anisotropic Dicke models including the Tavis-Cummings model [@TC] without counterrotating terms have been reported [@AnistropicDicke] in the thermodynamic limit, i.e., infinite qubits. It was found in [JC\_Plenio]{} that the Jaynes-Cummings (JC) model  [@JC], the quantum Rabi model in the RWA, could also undergo the second-order QPT in the extreme model parameter limit, $\Delta /\omega \rightarrow \infty $ where $\Delta $ and $\omega $ are the frequencies of qubit and cavity. It was demonstrated that the ratio of frequencies $\Delta /\omega $ plays the same role as the qubits number, and the second-order QPT can be identified by finite frequency scaling analysis.

Since both the Dicke and Rabi models in the RWA undergo the second-order QPT, can 