We investigated kinetic properties of correlated pairing states in strongly correlated phase of the Hubbard model in two space dimensions. We employ an optimization variational Monte Carlo method, where we use the improved wave function ${\psi }_{\lambda }=e^{-\lambda K}{\psi }_G$ for the Gutzwiller wave function ${\psi }_G$ with K being the kinetic part of the Hamiltonian. The Gutzwiller-BCS state is stabilized as the potential energy driven superconductivity because the Coulomb interaction energy is lowered while the kinetic energy increases in this state. In contrast, we show that in the ${\psi }_{\lambda }$-BCS wave function ${\psi }_{\lambda -BCS}=e^{-\lambda K}{P}_G{\psi }_{BCS}$, the Coulomb energy increases and instead the kinetic energy is lowered in the strongly correlated phase where the Coulomb repulsive interaction U is large. The correlated superconducting state is realized as a kinetic energy driven pairing state and this indicates the enhancement of superconductivity due to kinetic-energy effect.

我们研究了二维空间中Hubbard模型的强相关相中相关配对状态的动力学特性。我们采用优化的变分蒙特卡罗方法，其中使用了改进的波动函数${\psi }_{\lambda }={Ë}^{-\lambda ķ}{\psi }_G$ 用于Gutzwiller波函数 ${\psi }_G$与ķ是哈密顿的动力部分。Gutzwiller-BCS状态稳定为势能驱动的超导性，因为在此状态下库仑相互作用能降低，而动能增加。相比之下，我们在${\psi }_{\lambda }$-BCS波功能 ${\psi }_{\lambda -乙C\mathrm{小号}}={Ë}^{-\lambda ķ}{P}_G{\psi }_{乙C\mathrm{小号}}$，在库仑排斥相互作用U大的强相关相中，库仑能量增加，而动能降低。相关的超导状态被实现为动能驱动的配对状态，这表明由于动能效应而使超导性增强。