Wronskian perturbation theoryWronskian perturbation theory

短距离和长距离的范德瓦尔斯相互作用：从定态到含时微扰理论的教学路径

Van der Waals interaction at short and long distances: a pedagogical path from stationary to time-dependent perturbation theory

研究中性原子间范德瓦尔斯相互作用在长短距离的情况，核心方法是用时序关联函数重述定态微扰理论计算，主要贡献是提供连接两种极限情况的统一框架，便于教学与专业研究。

Intrinsic Entropy of Squeezed Quantum Fields and Nonequilibrium Quantum Dynamics of Cosmological Perturbations

Density contrasts in the universe are governed by scalar cosmological perturbations which, when expressed in terms of gauge-invariant variables, contain a classical component from scalar metric perturbations and a quantum component from inflaton field fluctuations. It has long been known that the effect of cosmological expansion on a quantum field amounts to squeezing. Thus the entropy of cosmological perturbations can be studied by treating them in the framework of squeezed quantum systems. Entropy of a free quantum field is a seemingly simple yet subtle issue. In this paper, as different fro…

Optimized Perturbation Theory for Wave Functions of Quantum Systems

The notion of the optimized perturbation, which has been successfully applied to energy eigenvalues, is generalized to treat wave functions of quantum systems. The key ingredient is to construct an envelope of a set of perturbative wave functions. This leads to a condition similar to that obtained from the principle of minimal sensitivity. Applications of the method to quantum anharmonic oscillator and the double well potential show that uniformly valid wave functions with correct asymptotic behavior are obtained in the first-order optimized perturbation even for strong couplings.