Fröhlich 极化子的非经典基态

本文计及波矢 q,q' 声子间动力学关联效应,采用双模-压缩(声子)相干态作为再一次正则变换方案,基于Huybrechts变分近似,求解 Fröhlich 大极化子的非经典基态.由于双模-压缩(声子)相干态导致声子相干态-压缩声子态关联效应,相干参量 f_q 与双模压缩角 φqq' 关键词： 双模-压缩(声子)相干态 位移-声子压缩态 Frö hlich 极化子 非经典基态

Nonclassical ground state for Fröhlich palaron

Based on the variational approach proposed by Huybrecht , using the two-mode squeezed coherent state as the second-step canonical transformation, we have investigated the nonclassical ground state for the Fröhlich polaron through considering the dynamical correlation bewteen the phonon wave vectors q and q' . Due to the correlation effect between the phonon coherent state and the phonon squcezed state, caused by the two-mode squeezing effect of the phonon coherent state, the coherent parameter f_q and the two-mode squeezing angle φ_qq' also have a big correction correspondingly. As a result , this effect has greatly enhanced the coherent effect and the squeezing angle effect . The calculation and the analysis based on the ground state energy of the polaron have shown that 1) for the weakly coupled region ,the correction ΔE⁽¹⁾_c due to the effect of the displaced-phonon squcezed state is comparable to the Feynma n' s path integral calculation (ΔE_f) and the coherent state correetion by Huybrechts (ΔE₀), while the correction (ΔE⁽²⁾_c) due to the squeezing effect of the phonon coherent state has an essential contribution , i.e. ΔE⁽²⁾_c«(ΔE_f,ΔE₀); 2) for the strongly-coupled region ,the contribution from the displaced-phonon squcezed state has a greatly reduction , ΔE⁽¹⁾_c≥(ΔE_f,ΔE₀) .Althougth, at the same time ,the contribution due to the squeezing effect of the phonon coherent state also has a greatly reduction ,we still have ΔE⁽²⁾_c«(ΔE_f,ΔE₀).