arXiv subjects

Hong-Mei Zou

Publications and source records attributed to Hong-Mei Zou.

17 recordsLinked to original sources

arXiv2026

Entropy and Variance Squeezing of V-type Atom in Dissipative Cavity

Based on Ref.\cite{Riccardi A}, we investigate the entropy and variance squeezing of a V-type atom in a dissipative cavity, and discuss the influences of parameters including the spontaneously generated interference (SGI) ($\theta$), the cavity-environment coupling ($\gamma_0/\kappa$) and the atom-cavity detuning ($\Delta$) on the atomic squeezing by using different initial states. The results show that no squeezing of $S_y$ occurs under any condition and that variance squeezing of $S_x$ appears only when $\Delta>0$. Entropy squeezing quantifies quantum fluctuations more precisely than variance squeezing. Moreover, the atomic squeezing of $S_x$ clearly depends on $\theta$, $\gamma_0/\kappa$, $\Delta$ and the initial state. These findings are meaningful for quantum information processing as an ultra-low-noise resource.

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arXiv2025

Controlling Quantum Coherence of V-type Atom in Dissipative Cavity by Detuning and Weak Measurement Reversal

In this work, an interactive system composed of a V-type atom and a dissipative single-mode cavity is considered and the atomic quantum coherences are investigated under parameters including spontaneously generated interference (SGI), cavity-environment coupling, weak measurement and its reversal, and detuning between the atom and the cavity. The results indicate that, the strong coupling can induce coherence sudden death (CSD) and coherence sudden birth (CSB), and the non-zero SGI parameter only induces CSB but the detuning may avoid CSD and CSB. Moreover, detuning and weak measurement reversal can very effectively protect quantum coherence, while the SGI parameter, weak measurement, and strong coupling can accelerate its attenuation. The SGI parameter, detuning, weak measurement reversal, and strong coupling all promote the generation of coherence, whereas weak measurement alone can suppress it. In particular, the maximal coherent state can be very effectively protected and the coherent state can be prepared if all parameters are selected appropriately. Physical interpretations are also provided for these results.

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arXiv2024

Modulating Entanglement Dynamics of Two V-type Atoms in Dissipative Cavity by Detuning, Weak Measurement and Reversal

In this paper, how to modulate entanglement dynamics of two V-type atoms in dissipative cavity by detuning, weak measurement and weak measurement reversal is studied. The analytical solution of this model is obtained by solving Schrodinger Equation after diagonalizing Hamiltonian of dissipative cavity. It is discussed in detail how the entanglement dynamics is influenced by cavity--environment coupling, spontaneously generated interference (SGI) parameter, detuning between cavity with environment and weak measurement reversal. The results show that the entanglement dynamics of different initial states obviously depends on coupling, SGI parameter, detuning and reversing measurement strength. The stronger coupling, the smaller SGI parameter, the larger detuning and the bigger reversing measurement strength can all not only protect but also generate the entanglement, and the detuning is more effectively in tne strong coupling regime than the weak measurement reversal, which is more effectively than the SGI parameter. We also give corresponding physical interpretations.

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arXiv2023

Entanglement Dynamics of Two V-type Atoms with Dipole-Dipole Interaction in Dissipative Cavity

In this work, we study a coupled system of two V-type atoms with dipole-dipole interaction in a dissipative single-mode cavity, which couples with an external environment. We obtain the analytical solution of this model by solving the time dependent Schrodinger equation after we diagonalize Hamiltonian of dissipative cavity by introducing a set of new creation and annihilation operators according to Fano theorem. We also detailedly discuss the influences of cavity-environment coupling, spontaneously generated interference (SGI) parameter and dipole-dipole interaction between two atoms on entanglement dynamics under different initial states. The results show that the SGI parameter has different effects on entanglement dynamics under different initial states. Namely, the SGI parameter will increase the decay rate of the initially maximal entangled state and reduce that of the initially partial entangled state. For the initially product state, the larger SGI parameter corresponds to the more entanglement generated. The entanglement monotonically decreases under the weak cavity-environment coupling, while the oscillation of entanglement will occur under the strong cavity-environment coupling. The larger the dipole-dipole interaction is, the slower the entanglement decays and the more the entanglement will be generated. So the dipole-dipole interaction can not only protect and generate entanglement very effectively, but also enhance the regulation effect of the SGI parameter on entanglement.

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arXiv2023

Modulating quantum evolution of moving-qubit by using classical driving

In this work, we study quantum evolution of an open moving-qubit modulated by a classical driving field. We obtain the density operator of qubit at zero temperature and analyze its quantum evolution dynamics by using quantum speed limit time (QSLT) and a non-Markovianity measure introduced recently. The results show that both the non-Markovian environment and the classical driving can speed up the evolution process, this quantum speedup process is induced by the non-Markovianity and the critical points only depend on the qubit velocity. Moreover, the qubit motion will delay the evolution process, but this negative effect of the qubit velocity on the quantum speedup can be suppressed by the classical driving. Finally, we give the corresponding physical explanation by using the decoherence rates.

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arXiv2022

Entanglement dynamics of an open moving-biparticle system driven by classical-field

In this work, the entanglement dynamics of a moving-biparticle system driven by an external classical field are investigated, where the moving-biparticle system is coupled with a zero temperature common environment. The analytical expressions of the density operator and the entanglement can be obtained by using the dressed-state basis when the total excitation number is one. We also discuss in detail the effects of different parameters on the entanglement dynamics. The results show that the classical driving can not only protect the entanglement, but also effectively eliminate the influence of the qubit velocity and the detuning on the quantum entanglement.

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arXiv2020

Based-nonequilibrium-environment non-Markovianity, quantum Fisher information and quantum coherence

In this work, we investigate the non-Markovianity, quantum Fisher information (QFI) and quantum coherence of a qubit in a nonequilibrium environment and have obtained the expressions of QFI and quantum coherence as well as their relationship. We have also discussed in detail the influences of the different noise parameters on these quantum sffects. The results show that the suitable parameters of the nonequilibrium environment can retard the QFI and quantum coherence in both Markovian and non-Markovian regions. In addition, the smaller memory effects and the larger the jumping rate, the greater the QFI and quantum coherence. And a larger QFI naturally corresponds to a larger quantum coherence, which indicates that the quantum coherence can enlarge the QFI and can effectively enhance the quantum metrology.

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arXiv2020

Quantum speed-up process of atom in dissipative cavity

In this work, we obtain an analytical representation of the density operator of an atom in dissipative cavity when the reservoir is at zero temperature and the total number of excitation is N=1. We also investigated the quantum speed limit time(QSLT) of the atom and the non-Markovianity in the dynamics process. The results show that the QSLT and the non-Markovianity can be effectively manipulated by the atom-cavity coupling and the reservoir parameters. Both of the atom-cavity coupling and the detuning can induce a sudden transition from Markovian to non-Markovian dynamics and this transition is the main physical reason of the quantum speed-up process. The critical value of sudden transition from no speed-up to speed-up depends the atom-cavity coupling and the reservoir parameters. The corresponding physical explanation is also provided for our results.

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arXiv2020

Ohmic Reservoir-based non-Markovianity and Quantum Speed Limit Time

We study the non-Markovianity and quantum speedup of a two-level atom (quantum system of interest) in a dissipative Jaynes-Cumming model, where the atom is embedded in a single-mode cavity, which is leaky being coupled to an external reservoir with Ohmic spectral density. We obtain the non-Markovianity characterized by using the probability of the atomic excited state and the negative decoherence rate in the time-local master equation. We also calculate the quantum speed limit time (QSLT) of the evolution process of the atom. The results show that, the atom-cavity coupling is the main physical reasons of the transition from Markovian to non-Markovian dynamics and the transition from no speedup to speedup process, and the critical value of this sudden transition only depends on the Ohmicity parameter. The atom-cavity coupling and the appropriate reservoir parameters can effectively improve the non-Markovianity in the dynamics process and speed up the evolution of the atom. Moreover, the initial non-Markovian dynamics first turns into Markovian and then back to non-Markovian with increasing the atom-cavity coupling under certain condition. Finally, the physical interpretation is provided.

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arXiv2020

Quantum Fisher information and coherence of an atom in a dissipative cavity

In this work, we investigate quantum Fisher information(QFI) and quantum coherence(QC) of an atom in dissipative cavity. In zero temperature reservior and with one excitation number, we obtain the analytical solutions of QFI and QC as well as their relationship for Ohmic and Lorentzian reservoir, respectively. The results show that both of the atom-cavity coupling and the cavity-reservoir coupling can effectively protect QFI and QC. Especially, QFI and QC will tend to their stable values when the atom-cavity coupling or the cavity-reservoir coupling is larger than a certain value. QC can augment QFI and can effectively improve the quantum metrology. In addition, we give a physical explanation of the dynamic behavior of QFI and QC by using the decoherence rate.

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arXiv2020

Entanglement witness and entropy uncertainty of open Quantum systems under Zeno effect

The entanglement witness and the entropy uncertainty are investigated by using the pseudomode theory for the open two-atom system under the quantum Zeno effect. The results show that, only when the two spectrums satisfy strong coupling with the atom, the time of entanglement witness can be prolonged and the lower bound of the entropic uncertainty can be reduced, and the entanglement can be witnessed many times. We also gave the corresponding physical explanation by the non-Markovianity. The Zeno effect not only can very effectively prolong the time of entanglement witness and reduce the lower bound of the entropy uncertainty, but also can greatly enhance the time of entanglement witness and reduce the entanglement value of witness.

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arXiv2020

Quantum speed-up based on classical-field and moving-qubit

In this work, we provide a model of a moving-qubit interacting with the multimode cavity, where the qubit is driven by the classical field. We obtain the analytic solution of the density operator of the qubit, then investigate the quantum speed limit time(QSLT) and the non-Markovianity based on the classical field and the moving-velocity. The results show that the transition from Markovian to non-Markovian dynamics is the intrinsic physical reason of the quantum speed-up process, both of the driving field and the strong coupling can enhance the non-Markovianity in the dynamics process and speed up the evolution of the qubit, but the moving velocity of the qubit can decrease the non-Markovianity in dynamics process and delay the evolution of qubit. To some extent, the classical field can reduce the effect of the moving velocity of the qubit on the quantum evolution process.

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arXiv2019

Discord and entanglement in non-Markovian environments at finite temperature

The dynamics evolutions of discord and entanglement of two atoms in two independent Lorentzian reservoirs at zero or finite temperature have been investigated by using the time-convolutionless master-equation method. Our results show that, when both the non-Markovian effect and the detuning are present simultaneously, due to the memory and feedback effect of the non-Markovian reservoirs, the discord and the entanglement can be effectively protected even at nonzero temperature by increasing the non-Markovian effect and the detuning. The discord and the entanglement have different robustness for different initial states and their robustness may changes under certain conditions. Nonzero temperature can accelerate the decays of discord and entanglement and induce the entanglement sudden death.

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arXiv2019

Modulating quantum Fisher information of qubit in dissipative cavity by coupling strength

By using the non-Markovian master equation, we investigate the effect of the cavity and the environment on the quantum Fisher information (QFI) of an atom qubit system in a dissipation cavity. We obtain the formulae of QFI for two different initial states and analyze the effect of the atom-cavity coupling and the cavity-reservoir coupling on the QFI. The results show that the dynamic behavior of the QFI is obviously dependent on the initial atomic states, the atom-cavity coupling and the cavity-reservoir coupling. The stronger the atom-cavity coupling, the quicker the QFI oscillates and the slower the QFI reduces. Especially, the QFI will tend to a stable value not zero if the atom-cavity coupling is large enough. On the other hand, the smaller the cavity-reservoir coupling, the stronger the non-Markovian effect, the slower the QFI decay. In other words, choosing the best parameter can improve the accuracy of parameter estimation. In addition, the physical explanation of the dynamic behavior of the QFI is given by means of the QFI flow.

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arXiv2018

Squeezing of light field in a dissipative Jaynes-Cummings model

Based on the time-convolutionless master-equation approach, we investigate squeezing of light field in a dissipative Jaynes-Cummings model. The results show that squeezing light can be generated when the atom transits to a ground state from an excited state, and then a collapse-revival phenomenon will occur in the squeezing of light field due to atom-cavity coupling. Enhancing the atom-cavity coupling can increase the frequency of the collapse-revival of squeezing. The stronger the non-Markovian effect is, the more obvious the collapse-revival phenomenon is. The oscillatory frequency of the squeezing is dependents on the resonant frequency of the atom-cavity.

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arXiv2018

The quantum entropic uncertainty relation and entanglement witness in the two-atom system coupling with the non-Markovian environments

The quantum entropic uncertainty relation and entanglement witness in the two-atom system coupling with the non-Markovian environments are studied by the time-convolutionless master-equation approach. The influence of non-Markovian effect and detuning on the lower bound of the quantum entropic uncertainty relation and entanglement witness is discussed in detail. The results show that, only if the two non-Markovian reservoirs are identical, increasing detuning and non-Markovian effect can reduce the lower bound of the entropic uncertainty relation, lengthen the time region during which the entanglement can be witnessed, and effectively protect the entanglement region witnessed by the lower bound of the entropic uncertainty relation. The results can be applied in quantum measurement, quantum cryptography task and quantum information processing.

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arXiv2018

Analytical solution and entanglement swapping of a double Jaynes-Cummings model in non-Markovian environments

Analytical solution and entanglement swapping of a double Jaynes-Cummings model in non-Markovian environments are investigated by the timeconvolutionless master equation method. We obtain the analytical solution of this model and discuss in detail the influence of atom-cavity coupling, non-Markovian effect and initial state purity on entanglement dynamics. The results show that, in the non-Markovian environments, the entanglement between two cavities can be swapped to other bipartite subsystems by interaction between an atom and its own cavity. Due to the dissipation of environment, the entanglements of all bipartite subsystems will eventually decay to zero when the atom couples weakly to its cavity and the non-Markovian effect is also weak. All bipartite subsystems can tend to steady entanglement states if and only if there is the strong atom-cavity coupling or the strong non-Markovian effect. The steady state of the subsystem composed of an atom and its own cavity is independent on the purity but the steady states of other bipartite subsystems are dependent on the purity.

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