Analytic Expansion for Ground-State Wavefunction of Time-Dependent Strong-Coupling Schrodinger Equation

The new method proposed recently by Friedberg, Lee, and Zhao is extended to obtain an analytic expansion for the ground-state wavefunction of a time-dependent strong-coupling Schroedinger equation. Two different types of the time-dependent harmonic oscillators are considered as examples for application of the time-dependent expansion. It is show that the time-dependent strong-coupling expansion is applicable to the time-dependent harmonic oscillators with a slowly varying time-dependent parameter.

The optical phonon drag effect on strong-coupling decay magnetopolaron in Gaussian alkali halogen ionic quantum wells

The polaron phenomenon is commonly observed in low-dimensional semiconductor materials and is known to have unique effects on conductive material properties.Furthermore,the phonon dragging effect,which leads to the polaron energy level,is less than the electron energy level.A decay magnetic field also affects the polaron effect,which causes polaron energy level changes.We demonstrate the unique electron-phonon coupling properties of this polaron using numerical calculations.Our findings have strong implications for theories of polaron properties and provide compelling evidence for a semiconductor device that industrial manufacturers use for new lowdimensional materials.

On the Superconductivity in High-Entropy Alloy (NbTa)1-X(HfZrTi)X

The superconductivity in (NbTa)1-X(HfZrTi)X high-entropy alloy is analyzed using the theory of strong-coupled superconductor. It is concluded that (NbTa)1-X(HfZrTi)X is a strong coupled superconductor. The variation in the superconducting transition temperature from 7.9 K to 4.6 K as x increases from 0.2 to 0.84 arises because of the decrease in electronic band width due to localization and broadening of the band. It is suggested that the decrease in electronic band width is due to crystalline randomness which gives rise to the mobility edge.

Two-Site Holstein Model： a Variational Wavefunction Analysis

A novel variational approach is proposed to calculate the ground-state （GS） properties of the two-site Holstein model. By the linear superposition of two coherent states, which simulate the behaviour of the weak and strong coupling limits, we can obtain very accurate GS energy for arbitrary electron-phonon coupling constant. Other GS properties are also discussed. Moreover, the present concise approach is hopefully generalized to many other Holstein models.

Quantum parametric amplification of phonon-mediated magnon-spin interaction

The recently developed hybrid magnonics provides new opportunities for advances in both the study of magnetism and the development of quantum information processing.However,engineering coherent quantum state transfer between magnons and specific information carriers,in particular,mechanical oscillators and solid-state spins,remains challenging due to the intrinsically weak interactions and the frequency mismatch between different components.Here,we show how to strongly couple the magnon modes in a nanomagnet to the quantized mechanical motion(phonons)of a micromechanical cantilever in a hybrid tripartite system.The coherent and enhanced magnon-phonon coupling is engineered by introducing the quantum parametric amplification of the mechanical motion.With experimentally feasible parameters,we show that the mechanical parametric drive can be adjusted to drive the system into the strong-coupling regime and even the ultrastrong-coupling regime.Furthermore,we show the coherent state transfer between the nanomagnet and a nitrogen-vacancy center in the dispersive-coupling regime,with the magnon-spin interaction mediated by the virtually-excited squeezed phonons.The amplified mechanical noise can hardly interrupt the coherent dynamics of the system even for low mechanical quality factors,which removes the requirement of applying additional engineered-reservoir techniques.Our work opens up prospects for developing novel quantum transducers,quantum memories and high-precision measurements.

Study of the cavity-magnon-polariton transmission line shape

We experimentally and theoretically investigate the microwave transmission line shape of the cavity-magnon-polariton(CMP)created by inserting a low damping magnetic insulator into a high quality 3D microwave cavity. While fixed field measurements are found to have the expected Lorentzian characteristic, at fixed frequencies the field swept line shape is in general asymmetric. Such fixed frequency measurements demonstrate that microwave transmission can be used to access magnetic characteristics of the CMP,such as the field line width H. By developing an effective oscillator model of the microwave transmission we show that these line shape features are general characteristics of harmonic coupling. At the same time, at the classical level the underlying physical mechanism of the CMP is electrodynamic phase correlation and a second model based on this principle also accurately reproduces the experimental line shape features. In order to understand the microscopic origin of the effective coupled oscillator model and to allow for future studies of CMP phenomena to extend into the quantum regime, we develop a third, microscopic description,based on a Green's function formalism. Using this method we calculate the transmission spectra and find good agreement with the experimental results.