Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education), Department of Physics, Shanghai Jiao Tong University, Shanghai 200240, China.
J Chem Phys. 2013 May 7;138(17):174117. doi: 10.1063/1.4803661.
An analytic ground state is proposed for the unbiased spin-boson Hamiltonian, which is non-Gaussian and beyond the Silbey-Harris ground state with lower ground state energy. The infrared catastrophe in Ohmic and sub-Ohmic bosonic bath plays an important role in determining the degeneracy of the ground state. We show that the infrared divergence associated with the displacement of the nonadiabatic modes in bath may be removed from the proposed ground state for the coupling α < αc. Then αc is the quantum critical point of a transition from non-degenerate to degenerate ground state and our calculated αc agrees with previous numerical results.
提出了非各向同性自旋-玻色子哈密顿量的解析基态，该基态是非高斯的，并且具有更低的基态能量，超越了 Silbey-Harris 基态。欧姆和次欧姆玻色子浴中的红外灾难在确定基态的简并度方面起着重要作用。我们表明，与浴中非绝热模式的位移相关的红外发散可以从耦合 α < αc 的建议基态中消除。然后，αc 是从非简并基态到简并基态的转变的量子临界点，我们计算的 αc 与先前的数值结果一致。
