Liwei Duan
Zhejiang University
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Liwei Duan.
Journal of Chemical Physics | 2013
Ning Wu; Liwei Duan; Xin Li; Yang Zhao
The Dirac-Frenkel time-dependent variation is employed to probe the dynamics of the zero temperature sub-Ohmic spin-boson model with strong friction utilizing the Davydov D1 ansatz. It is shown that initial conditions of the phonon bath have considerable influence on the dynamics. Counterintuitively, even in the very strong coupling regime, quantum coherence features still manage to survive under the polarized bath initial condition, while such features are absent under the factorized bath initial condition. In addition, a coherent-incoherent transition is found at a critical coupling strength α ≈ 0.1 for s = 0.25 under the factorized bath initial condition. We quantify how faithfully our ansatz follows the Schrödinger equation, finding that the time-dependent variational approach is robust for strong dissipation and deep sub-Ohmic baths (s ≪ 1).
Journal of Chemical Physics | 2013
Liwei Duan; Hui Wang; Qing-Hu Chen; Yang Zhao
Developed originally for the Holstein polaron, the Davydov D1 ansatz is an efficient, yet extremely accurate trial state for time-dependent variation of the spin-boson model [N. Wu, L. Duan, X. Li, and Y. Zhao, J. Chem. Phys. 138, 084111 (2013)]. In this work, the Dirac-Frenkel time-dependent variational procedure utilizing the Davydov D1 ansatz is implemented to study entanglement dynamics of two qubits under the influence of two independent baths. The Ohmic spectral density is used without the Born-Markov approximation or the rotating-wave approximation. In the strong coupling regime finite-time disentanglement is always found to exist, while at the intermediate coupling regime, the entanglement dynamics calculated by Davydov D1 ansatz displays oscillatory behavior in addition to entanglement disappearance and revival.
Journal of Chemical Physics | 2013
Jin Sun; Liwei Duan; Yang Zhao
An efficient, yet very accurate trial wave function, constructed from projecting the well-known Davydov D1 Ansatz onto momentum eigenstates, is employed to study the ground state properties of the generalized Holstein Hamiltonian with simultaneous diagonal and off-diagonal coupling. Ground-state energies have been obtained with a precision matching that of the computationally much more demanding density-matrix renormalization group method. The delocalized D1 Ansatz lowers the ground-state energies at the Brillouin zone boundary significantly compared with the Toyozawa and Global-Local Ansätze in the weak coupling regime, while considerable improvement is demonstrated to have been achieved over the entire Brillouin zone in the strong coupling regime. Unique solutions are obtained with the delocalized D1 for different initial conditions when the transfer integral is 20 times the phonon frequency at the zone center, implying the absence of any self-trapping discontinuity. The scaled correlation variance is found to fit satisfactorily well with the predictions of the perturbation theories.
EPL | 2015
Liwei Duan; Shu He; Daniel Braak; Qing-Hu Chen
The two-mode quantum Rabi model with bilinear coupling is studied using extended squeezed states. We derive G-functions for each Bargmann index q. They share a common structure with the G-function of the one-photon and two-photon quantum Rabi models. The regular spectrum is given by zeros of the G-function while the conditions for the presence of doubly degenerate (exceptional) eigenvalues are obtained in closed form through the lifting property. The simple singularity structure of the G-function allows to draw conclusions about the distribution of eigenvalues along the real axis and to understand the spectral collapse phenomenon when the coupling reaches a critical value.
Journal of Physics A | 2016
Liwei Duan; You-Fei Xie; Daniel Braak; Qing-Hu Chen
The two-photon quantum Rabi model with quadratic coupling is studied using extended squeezed states and we derive
New Journal of Physics | 2015
Shu He; Liwei Duan; Qing-Hu Chen
G
Journal of Chemical Physics | 2012
Yuyu Zhang; Liwei Duan; Qing-Hu Chen; Yang Zhao
-functions for Bargmann index
EPL | 2014
Hui Wang; Shu He; Liwei Duan; Yang Zhao; Qing-Hu Chen
q=1/4
Journal of Chemical Physics | 2013
Zhiguo Lü; Liwei Duan; Xin Li; Prathamesh M. Shenai; Yang Zhao
and
Annals of Physics | 2015
Liwei Duan; Shu He; Qing-Hu Chen
3/4