arXiv subjects

Ju-Kui Xue

Publications and source records attributed to Ju-Kui Xue.

6 recordsLinked to original sources

arXiv2025

The controlled exciton transport of the Multi-chain system by cavity-dressed energy level crossings and anticrossings

The performance of various quantum devices is fundamentally linked to the control of exciton transport. To explore this, we study the exciton transport of the two-dimensional multi-chain systems with different coupling configurations in an optical cavity. Two types of the chains--the homogeneous and heterogeneous coupling chain, as well as two inter-chain coupling conformations--the square and triangular arrangements, are considered. The effects of the inter-chain coupling, the dimerization parameter, the cavity, the length and number of the chains on exciton transport are systematically investigated for different coupling configurations through the spectra, the Hopfield coeffcients, and the steady-state dynamics of the system. The results show that in the absence of a cavity the exciton transport currents and effciency are determined by the exciton distribution across the multi-chain system. However, when a cavity is introduced the exciton transport can be significantly enhanced or suppressed by the polariton formation at the cavity-dressed energy level crossings and anticrossings near zero-energy modes, where the coherent excitation and LandauZener transitions occur. Meanwhile, we discover that the discontinuous and extremal points in the second-order partial derivatives of the photon Hopfield coeffcients with respect to the inter-chain coupling and the dimerization parameter correspond respectively to the crossings and anticrossings at the extreme points of the photon occupation number. Additionally, exciton transport effciency is closely related to the odevity of both chain length and chain number, and exhibits oscillatory behaviour. This work provides critical insights into the exciton transport mechanism in multichain-cavity system and theoretical basis for designing high-erformance excitonic devices with tunable transport properties.

quant-ph↗

arXiv2022

The anomalous process in singlet fission kinetic model with time-dependent coefficient

In the third generation photovoltaic device, the main physical mechanism that the photoelectric conversion efficiency is enhanced is the singlet fission (SF). In order to accurately describe the SF and reveal physical process in theoretically, we introduce the anomalous process (AP) in SF dynamics based on previous model, including anomalous fission, anomalous fusion, anomalous dissociation and combination of triplet pair states, anomalous decay and diffusion of single triplet exciton. The effects of the AP on SF are investigated by the kinetic model with time-dependent coefficient. Further, according to the results we make the optimal simulations for the experimental data [G. B. Piland et al., J. Phys. Chem. C, 2013, 117, 1224] by adjusting the rate coefficients and exponents in the mended kinetic equations. The results show that the model considered AP is more accurate than previous that to describe SF dynamics, demonstrating that the AP do exist in SF. The model also provides the theoretical foundation for how varies experimentally physical factors to make SF occur to tend to required direction.

physics.chem-ph↗

arXiv2021

All-optical transistor with cavity polaritons

we investigate the transmission of probe laser beam in a coupled-cavity system with polaritons by using standard input-output relation of optical fields, and proposed a theoretical schema for realizing a polariton-based photonic transistor. On account of effects of exciton-photon coupling and single-photon optomechanical coupling, a probe laser field can be either amplified or attenuated by another pump laser field when it passes through a coupled-cavity system with polaritons. The Stokes and anti-Stokes scattered effect of output prober laser can also be modulated. Our results open up exciting possibilities for designing photonic transistors.

physics.optics↗

arXiv2020

Pumping-assisted multistability of exciton-polariton condensates

We investigate the multistability of exciton-polariton condensates excited by a nonresonant pump. An increase in pumping power moves the system away from non-Hermitian spectral degeneracy towards spectrum splitting through an exceptional point, which induces a transition from monostability to multistability. In the region of multistability, the system contains one steady and two metastable states. The analyses of stability show that metastable states maintain a finite lifetime and eventually evolve to steady states. A steady state with multi-peak soliton different from general single-peak soliton is discovered for attractive polariton-polariton interaction. Moreover, we depict the diagram of the multistability in full parameter space to accurately manipulate the multistability. Our results open up exciting possibilities for controlling non-Hermitian quantum multistable states, which may be useful to designing polariton-based devices exploiting optical multistability.

cond-mat.quant-gas↗

arXiv2007

Self-Trapping of Bose-Einstein Condensates in an Optical Lattice: the Effect of the System Dimension

In the present paper, we investigate the dynamics of a Bose-Einstein condensates (BEC) loaded into an deep optical lattice of 1D, 2D and 3D, both analytically and numerically. We focus on the self-trapping state and the effect of the system dimension. Under the tight-binding approximation we obtain an analytical criterion for the self-trapping state of BEC using time-dependent variational method. The phase diagram for self-trapping, soliton, breather, or diffusion of the BEC cloud is obtained accordingly and verified by directly solving the discrete Gross-Pitaevskii equation (GPE) numerically. In particular, we find that the criterion and the phase diagrams are modified dramatically by the dimension of the lattices.

cond-mat.mes-hall↗

arXiv2006

Collective excitations of a Bose-Einstein condensate in an anharmonic trap

We investigate the collective excitations of a one-dimensional Bose-Einstein condensate (BEC) with repulsive interaction between atoms in a quadratic plus quartic trap. By using the variational approach, the coupled equations of motion for the center-of-mass coordinate of the condensate and its width are derived. Then, two low-energy excitation modes are obtained analytically. The frequency shift induced by the anharmonic distortion, and the collapse and revival of the collective excitations, which originate from the nonlinear coupling between the two modes, are discussed.

cond-mat.mes-hall↗