arXiv subjects

H. T. Cui

Publications and source records attributed to H. T. Cui.

At least 19 recordsLinked to original sources

arXiv2026

Anomalous mobility edges and extended-localized transition in a quasiperiodic emitter-cavity array

The manipulation of localization in quasiperiodic systems by mobility edges or localization transition holds significant physical importance. In this letter, we demonstrated that the dissipation can induce the emergence of anomalous mobility edges and extended-localized transition in emitter-cavity arrays controlled by quasiperiodic potentials. Specifically, we observe that the localization properties of emitters is governed by the nature of quantum bound states, either discrete or embedded in continuum, providing a unified mechanism linking the emitter-photon bound physics to quasiperiodic criticality. Depending on the bound state discrete or continuumlike, the induced effective excitation hopping exhibits either exponentially decaying or sinusoidally oscillating, giving rise to the formation of localized or critical states, respectively. Through a generalized duality transformation, we analytically determine the anomalous mobility edges and the critical strength of potential, enabling the construction of a full phase diagram. The study reveals that the physical characteristics of cavity exert a significant influence on excitation localization. Therefore, the manipulation of excitation localization can be achieved solely by adjusting the cavity fields.

quant-ph↗

arXiv2025

Quantum Mpemba effect of localization in the dissipative mosaic model

The quantum Mpemba effect in open quantum systems has been extensively studied, but a comprehensive understanding of this phenomenon remains elusive. In this paper, we conduct an analytical investigation of the dissipative dynamics of single excitations in the The mosaic model. Surprisingly, we discover that the presence of an asymptotic mobility edge, denoted as $E_c^{\infty}$, can lead to unique dissipation behavior, serving as a hallmark of the quantum Mpemba effect. Especially, it is found that the energy level $E_c^{\infty}$ exhibits a global periodicity in the real configuration, which acts to inhibit dissipation in the system. Conversely, when the system deviates from $E_c^{\infty}$, the quasidisorder sets in, leading to increased dissipative effects due to the broken of periodicity. Furthermore, we find that the rate of dissipation is closely linked to the localization of the initial state. As a result, the quantum Mpemba effect can be observed clearly by a measure of localization.

quant-ph↗

arXiv2024

Effective Hamiltonian approach to the quantum phase transitions in the extended Jaynes-Cummings model

The study of phase transitions in dissipative quantum systems based on the Liouvillian is often hindered by the difficulty of constructing a time-local master equation when the system-environment coupling is strong. To address this issue, the complex discretization approximation for the environment is proposed to study the quantum phase transition in the extended Jaynes-Cumming model with an infinite number of boson modes. This approach yields a non-Hermitian effective Hamiltonian that can be used to simulate the dynamics of the spin. It is found that the ground state of this effective Hamiltonian determines the spin dynamics in the single-excitation subspace. Depending on the opening of the energy gap and the maximum population of excitations on the spin degree of freedom, three distinct phases can be identified: fast decaying, localized, and stretched dynamics of the spin. This approach can be extended to multiple excitations, and similar dynamics were found in the double-excitation subspace, indicating the robustness of the single-excitation phase.

quant-ph↗

arXiv2023

Effective Hamiltonian approach to the exact dynamics of open system by complex discretization approximation for environment

The discretization approximation method commonly used to simulate the dynamics of quantum system coupled to the environment in continuum often suffers from the periodically partial recovery of initial state because of the effect of finite dimension, dubbed the recurrence. To address this issue, we proposes a generalization of the discretization approximation method into the complex frequency space basing on complex Gauss quadratures. An effective Hamiltonian can be established by this way, which is non-Hermitian and demonstrates the complex energy modes with negative imaginary part, describing the dissipation of the system. This method is applied to examine the dynamics in two exactly solvable models, the dephasing model and the single-excitation dissipative dynamics in the Aubry-Andr\'{e}-Harper model. By comparison with the exact numerics and analytical results, it is found that our approach not only significantly reduces the effect of recurrence and improve the effectiveness of calculation, but also provide a unique perspective into the dynamics of open system from the point of complex energy levels. Furthermore, we establish a simple relationship between the parameters in computation and the effectiveness of simulation by analyzing the computational error.

quant-ph↗

arXiv2022

Localization-enhanced dissipation in a generalized Aubry-André-Harper model coupled with Ohmic baths

In this work, the exact dynamics of excitation in the generalized Aubry-André-Harper model coupled with an Ohmic-type environment is discussed by evaluating the survival probability and inverse participation ratio of the state of system. In contrast to the common belief that localization will preserve the information of the initial state in the system against dissipation into the environment, our study found that strong localization can enhance the dissipation of quantum information instead. By a thorough examination of the dynamics, we show that the coherent transition between the energy state of system is crucial for understanding this unusual behavior. Under this circumstance, the coupling induced energy exchange between the system and its environment can induce the periodic population of excitation on the states of system. As a result, the stable or localization-enhanced decaying of excitation can be observed, dependent on the energy difference between the states of system. This point is verified in further by checking the varying of dynamics of excitation in the system when the coupling between the system and environment is more strong.

quant-ph↗

arXiv2021

Open dynamics in the Aubry-André-Harper model coupled to a finite bath: the influence of localization in the system and dimensionality of bath

The population evolution of single excitation is studied in the Aubry- André- Harper (AAH) model coupled to a $d (=1,2,3)$-dimensional simple lattices bath with a focus on the effect of localization in the system and the dimensionality of bath. By performing a precise evaluation of time-independent Schrödinger equation, the reduced energy levels of the system can be determined. It is found that the reduce energy levels show significant relevance for the bath dimensions. Subsequently, the time evolution of excitation is studied in both the system and bath. It is found that excitation in the system can decay super-exponentially when $d=1$ or exponentially when $d=2,3$. Regarding the finite nature of bath, the spreading of excitation in the lattices bath is also studied. We find that, depending on the dimensions of bath and the initial state, the spreading of excitation in the bath is diffusive or behaves localization.

quant-ph↗

arXiv2020

Edge state, bound state and anomalous dynamics in the Aubry-André-Haper system coupled to non-Markovian baths

Bound states and their influence on the dynamics of an one-dimensional tight-binding system subject to environments are studied in this paper. We identify specifically three kinds of bound states. The first is a discrete bound state (DBS), of which the energy level exhibits a gap from the continuum. The DBS exhibits the similar features of localization as the edge states in the system and thus can suppress the decay of system. The second is a bound state in the continuum (BIC), which can suppress the system decay too. It is found that the BIC is intimately connected to the edge mode of the system since both of them show almost the same features of localization and energy. The third one displays a large gap from the continuum and behaves extendible (not localized). Moreover the population of the system on this state decays partly but not all of them does. This is different from the two former bound states. The time evolution of a single excitation in the system is studied in order to illustrate the influence of the bound states. We found that both DBS and BIC play an important role in the time evolution, for example, the excitation becomes localized and not decay depending on the overlap between the initial state and the DBS or BIC. Furthermore we observe that the single excitation takes a long-range hopping when the system falls into the regime of strong localizations. This feature can be understood as the interplay of system localizations and the bath-induced long-range correlation.

quant-ph↗

arXiv2017

Bound state and Localization of excitation in many-body open systems

Bound state and time evolution for single excitation in one dimensional XXZ spin chain within non-Markovian reservoir are studied exactly. As for bound state, a common feature is the localization of single excitation, which means the spontaneous emission of excitation into reservoir is prohibited. Exceptionally the pseudo-bound state can always be found, for which the single excitation has a finite probability emitted into reservoir. We argue that under limit $N\rightarrow \infty$ the pseudo-bound bound state characterizes an equilibrium between the localization in spin chain and spontaneous emission into reservoir. In addition, a critical energy scale for bound states is also identified, below which only one bound state exists and it also is pseudo-bound state. The effect of quasirandom disorder is also discussed. It is found in this case that the single excitation is more inclined to locate at some spin sites. Thus a many-body-localization like behavior can be found. In order to display the effect of bound state and disorder on the preservation of quantum information, the time evolution of single excitation in spin chain studied exactly by numerically solving the evolution equation. A striking observation is that the excitation can be stayed at its initial location with a probability more than 0.9 when the bound state and disorder coexist. However if any one of the two issues is absent, the information of initial state can be erased completely or becomes mixed. Our finding shows that the combination of bound state and disorder can provide an ideal mechanism for quantum memory.

quant-ph↗

arXiv2016

Detecting ground-state degeneracy in many-body systems through qubit decoherence

By coupling with a qubit, we demonstrate that qubit decoherence can unambiguously detect the occurrence of ground-state degeneracy in many-body systems. We first demonstrate universality using the two-band model. Consequently, several exemplifications, focused on topological condensed matter systems in one, two, and three dimensions, are presented to validate our proposal. The key point is that qubit decoherence varies significantly when energy bands touch each other at the Fermi surface. In addition, it can partially reflect the degeneracy inside the band. This feature implies that qubit decoherence can be used for reliable diagnosis of ground-state degeneracy.

quant-ph↗

arXiv2013

Topology of Entanglement in Multipartite States with Translational Invariance

The topology of entanglement in multipartite states with translational invariance is discussed in this article. Two global features are foundby which one can distinguish distinct states. These are the cyclic unit and the quantised geometric phase. Furthermore the topology is indicated by the fractional spin. Finally a scheme is presented for preparation of these types of states in spin chain systems, in which the degeneracy of the energy levels characterises the robustness of the states with translational invariance.

quant-ph↗

arXiv2011

Maximal Overlap with a Fully Separable State and Translational Invariance in Multipartite Entangled States

The maximal overlap with the fully separable state for the multipartite entangled pure state with translational invariance is studied explicitly by some exact and numerical evaluations, focusing on the one-dimensional qubit system and some representative types of translational invariance. The results show that the translational invariance of the multipartite state could have an intrinsic effect on the determinations of the maximal overlap and the nearest fully separable state for multipartite entangled states. Furthermore a hierarchy of the basic entangled states with translational invariance is founded, from which one could readily find the maximal overlap and a related fully separable state for the multipartite state composed of different translational invariance structures.

quant-ph↗

arXiv2010

Geometric Entanglement in Valance-Bond-Solid state

Multipartite entanglement, measured by the geometric entanglement(GE), is discussed for integer spin Valance-Bond-Solid (VBS) state respectively with periodic boundary condition(PBC) and open boundary condition(OBC) in this paper. The optimization in the definition of geometric entanglement can be reduced greatly by exploring the symmetry of VBS state, and then the fully separable state can be determined explicitly. Numerical evaluation for GE by the random simulation is also implemented in order to demonstrate the validity of the reductions. Our calculations show that GE is saturated by a finite value with the increment of particle number, that means that the total entanglement for VBS state would be divergent under the thermodynamic limit. Moreover it is found that the scaling behavior of GE with spin number $s$ is fitted as $α\log (s+\tfracβ{s}+γ)+δ$, in which the values of the parameters $α, β, γ, σ$ are only dependent on the parity of spin $s$. A comparison with entanglement entropy of VBS state is also made, in order to demonstrate the essential differences between multipartite and bipartite entanglement in this model.

quant-ph↗

arXiv2010

Overlap with the Separable State and Phase Transition in the Dicke Model: Zero and Finite Temperature

Overlap with the separable state is introduced in this paper for the purpose of characterizing the overall correlation in many-body systems. This definition has clear geometric and physical meaning, and moreover can be considered as the generalization of the concept-Anderson Orthogonality Catastrophe. As an exemplification, it is used to mark the phase transition in the Dicke model for zero and finite temperature. And our discussion shows that it can faithfully reflect the phase transition properties of this model whether for zero or finite temperature. Furthermore the overlap for ground state also indicates the appearance of multipartite entanglement in Dicke model.

quant-ph↗

arXiv2009

Current-induced spin polarization for a general two-dimensional electron system

In this paper, current-induced spin polarization for two-dimensional electron gas with a general spin-orbit interaction is investigated. For isotropic energy spectrum, the in-plane current-induced spin polarization is found to be dependent on the electron density for non-linear spin-orbit interaction and increases with the increment of sheet density, in contrast to the case for $\bm k$-linear spin-orbit coupling model. The numerical evaluation is performed for InAs/InSb heterojunction with spin-orbit coupling of both linear and cubic spin-orbit coupling types. For $δ$-type short-range electron-impurity scattering, it is found that the current-induced spin polarization increases with increasing the density when cubic spin-orbit couplings are considered. However, for remote disorders, a rapid enhancement of current-induced spin polarization is always observed at high electron density, even in the case without cubic spin-orbit coupling. This result demonstrates the collision-related feature of current-induced spin polarization. The effects of different high order spin-orbit couplings on spin polarization can be comparable.

cond-mat.mes-hall↗

arXiv2009

Pairwise Entanglement and Geometric Phase in $d=2,3$-Dimensional Free-Fermion Lattice Systems

The pairwise entanglement, measured by concurrence and geometric phase in $d=2,3$-dimensional free-fermion lattice systems have been studied for the ground state in this paper. Their derivation with respect to the external parameter show the singularity closed to the phase transition points, and can be used to detect the phase transition in this model. Furthermore our studies show for the free-fermion model that both concurrence and geometric phase shows the intimate connection with the correlation functions. The possible relation between concurrence and geometric phase has been also discussed.

quant-ph↗

arXiv2008

Geometric Phase and Quantum Phase Transition : Two-Band Model

The connection between the geometric phase and quantum phase transition has been discussed extensively in the two-band model. By introducing the twist operator, the geometric phase can be defined by calculating its ground-state expectation value. In contrast to the previous numerical examinations, our discussion presents an exact calculation for the determination of the geometric phase. Through two representative examples, our calculation shows the intimate connection between the geometric phase and phase transition: different behaviors of the geometric phase can be identified in this paper, which are directly related to the energy gap above the ground state.

quant-ph↗

arXiv2008

Multiparticle Entanglement in the Lipkin-Meshkov-Glick Model

The multiparticle entanglement in the Lipkin-Meshkov-Glick model has been discussed extensively in this paper. Measured by the global entanglement and its generalization, our calculation shows that the multiparticle entanglement can faithfully detect quantum phase transitions. For an antiferromagnetic case the multiparticle entanglement reaches the maximum at the transition point, whereas for ferromagnetic coupling, two different behaviors of multiparticle entanglement can be identified, dependent on the anisotropic parameter in the coupling.

quant-ph↗

arXiv2006

A Study on the Sudden Death of Entanglement

The dynamics of entanglement and the phenomenon of entanglement sudden death (ESD) \cite{yu} are discussed in bipartite systems, measured by Wootters Concurrence. Our calculation shows that ESD appears whenever the system is open or closed and is dependent on the initial condition. The relation of the evolution of entanglement and energy transfer between the system and its surroundings is also studied.

quant-ph↗