双能态自旋-晶格声子耦合量子隧道系统的非经典能态和量子相干耗散

Non-classical energy state and quantum tunnling coherence dissipation for the two-state system with the spin coupled to the lattice phonon

采用关联表象变分波函数方案,介入三个非经典关联效应,求解有限温度双能态自旋-晶格声子耦合量子隧道系统的非经典态,着重研究化解由于粒子自旋-单声子相互作用引起的量子涨落导致双能态系统的退相干性量子耗散.这三个非经典关联效应是:1)声子位移-粒子自旋(σz)间强非绝热关联;2)声子压缩态效应及其伴随发生的单声子相干态-声子压缩态两过程相干效应;3)由关联表象导致的声子位移(UD)与声子压缩(US)的表象关联非绝热修正.结果表明:由于引入粒子自旋-双声子相互作用,大幅度地增强了声子场压缩态,特别是更进一步极大幅度地增强了非经典压缩-相干态效应.因此,由粒子自旋-单声子相互作用产生的Debye-Walle相干弹性散射效应导致量子隧道项(0σx)的强烈指数衰减及其伴随严重的量子相干损失的极大幅度的抑制,并且自旋-晶格声子耦合量子隧道系统的非经典态能量大幅度降低.

Including the spin-two-phonon interaction, for the two-state tunneling system with the spin coupled to the lattice phonon （i.e., spin-lattice phonon coupling model） at a finite temperature, the non-classical energy state and the quantum coherence dissipation are studied by the expansion approach of the correlated squeezed-coherent state of phonon. To restrain the quantum coherence loss caused by the Debye-Waller′s coherent scattering of the particle spin by the coherent phonons, the non-classical correlation effects are used in our research with the special consideration of the spin-two-phonon interaction, i.e., 1） the particle spin-displaced phonon state correlation;2） the process coherence between the one-phonon coherent state and the phonon squeezed state which originates from the squeezed-coherent state of phonon;3） the renormalization of the phonon displacement. We find the new phenomena that the phonon squeezed state is enhanced significantly due to the particle spin-two phonon interaction, in particular, at the same time the effects of the squeezed coherent state and the representation correlation will be essentially increased. Therefore, the striking decline in the quantum tunneling （？0σx ） and the serious quantum coherence loss by the Debye-Waller coherent scattering are restricted more noticeably, as a result, the energy of the non-classical state for the two-level system with spin coupled to the lattice phonon is much lower.