Numerical approach for the evolution of spin-boson systems and its application to the Buck–Sukumar model

Liu, Xueying; Xue-Zao, Ren; Wang, Chen; Xianlong, Gao; Wang, Kelin

doi:10.1088/1572-9494/ab8a0f

Cited by 4 publications

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References 36 publications

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“…其中才有定义 [31,33] . 考虑到依赖强度Dicke模型可能出现能谱塌缩现象, 因此在下面的讨论中, 选择二能级原子系统和腔场之间的耦合参数g不是很大的情况, 如 , 这些耦合参数的取值与文献 [6]研究基于双光子Dicke模型的量子电池是相同的.…”

Section: 基于依赖强度Dicke模型的量子电池模型unclassified

“…后来, Ng等 [31] 利用幺正变换解析求解了具有反旋波项的B-S模型. 然而, 同双光子耦合方式类似 [32,33] , 依赖强度B-S模型也会遭遇相同的能谱塌缩现象, 即B-S模型只有在耦合常数小于某一临界值时才有定义 [31,33] 且反旋波项不会改变这种性质, 只是减小了这个临界值 [34] . 2016年, Valverde等 [35] 建议了用库珀对箱与纳米机械共振器间的相互作用来模拟依赖强度B-S模型的方案, 这为依赖强度B-S模型的实验实现提供了一条可能途径.…”

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Charging performance of quantum batteries based on intensity-dependent Dicke model

Huang,

He,

Chen

2023

Acta Phys. Sin.

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Recently, quantum battery based on various physical models from quantum optics model to spin model and its enhancement of charging performance have attracted increasing interest. It has demonstrated that quantum entanglement is beneficial for the speedup of work extraction. In this paper, the charging performance of the field intensity-dependent Dicke model (also called intensity-dependent Dicke model) quantum battery consisting of N qubits collectively interacting with a single mode cavity is investigated by an exact diagonalization approach. The considered intensity-dependent Dicke model is a generalized Dicke model with a nonlinear-coupling fashion and different weights of energy conserved and non-conserved terms. Firstly, we consider the influence of energy non-conserved term (also called anti-rotating wave term) on the maximum stored energy and maximum charging power in quantum batteries. It is shown that the maximum stored energy is not very sensitive to the increase of the weight of energy non-conserved term, but the maximum charging power will undergo a significant change with the increase of the weight of energy non-conserved term. We also show that the maximum charging power monotonically increases the coupling constant between qubits and cavity, but the maximum stored energy is not monotonic relation with the increase of coupling constant. Further, we examine in detail the characteristics of the maximum stored energy, charging time, energy quantum fluctuation and maximum charging power in the quantum battery under the same weight between energy conserved and non-conserved terms. By comparing the charging performance of quantum batteries based on single photon and two-photon Dicke models, it is shown that the performances both the charging times and maximum charging power of the intensity-dependent Dicke quantum battery is better than that of single-photon Dicke quantum battery, but is weaker than that of two-photon Dicke quantum battery. Of particular interest is, we find that the quantum advantage of maximum charging power for the superlinear scaling relation with large quantum cell numbers in the both intensity-dependent and two-photon Dicke quantum batteries are the same, namely $P_{max}^{ID} \propto N^2$ and $P_{max}^{2ph} \propto N^2$, which is consistent with the upper bound given by the paper (Gyhm J, Šafrǎnek D, Rosa D 2022 Phys. Rev. Lett. 128 140501). It is worth to mention that Dou et al. (Dou F Q, Zhou H, Sun J A 2022 Phys. Rev. A 106 032212) shown that the quantum advantage of maximum charging power in the quantum battery based on cavity Heisenberg-spin-chain model can get Pmax ∝ N2. Therefore, this study on the charging performance based on the intensity-dependent Dicke quantum battery may provide an alternative scheme for further research on quantum battery.

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Section: 基于依赖强度Dicke模型的量子电池模型unclassified

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Charging performance of quantum batteries based on intensity-dependent Dicke model

Huang,

He,

Chen

2023

Acta Phys. Sin.

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Density Operator Approach to Turbulent Flows in Plasma and Atmospheric Fluids

Zloshchastiev

2020

Universe

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We formulate a statistical wave-mechanical approach to describe dissipation and instabilities in two-dimensional turbulent flows of magnetized plasmas and atmospheric fluids, such as drift and Rossby waves. This is made possible by the existence of Hilbert space, associated with the electric potential of plasma or stream function of atmospheric fluid. We therefore regard such turbulent flows as macroscopic wave-mechanical phenomena, driven by the non-Hermitian Hamiltonian operator we derive, whose anti-Hermitian component is attributed to an effect of the environment. Introducing a wave-mechanical density operator for the statistical ensembles of waves, we formulate master equations and define observables: such as the enstrophy and energy of both the waves and zonal flow as statistical averages. We establish that our open system can generally follow two types of time evolution, depending on whether the environment hinders or assists the system’s stability and integrity. We also consider a phase-space formulation of the theory, including the geometrical-optic limit and beyond, and study the conservation laws of physical observables. It is thus shown that the approach predicts various mechanisms of energy and enstrophy exchange between drift waves and zonal flow, which were hitherto overlooked in models based on wave kinetic equations.

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The photon blockade effect of a complete Buck-Sukumar model

Liu¹,

Cheng²,

Xianlong³

2022

Acta Phys. Sin.

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<sec>The Buck-Sukumar (BS) model, with a nonlinear coupling between the atom and the light field, is well defined only when its coupling strength is lower than a critical coupling. Its energy collapses at a critical coupling and is unbounded beyond that value. In other words, the BS model is incomplete. We introduce a simple and a complete BS model by adding a nonlinear photon term into the initial BS model. Considering the rotating wave approximation, this complete BS model conserves the excited number and the parity. By expanding it in the subspace of the product state between the atom and the field, we solve the time-independent Schrödinger equation to obtain the eigenenergy and eigenstate. Furthermore, we explore the influence of the nonlinear photon term on the energy spectrum and the photon blockade effect for the complete BS model by calculating the excited number and second-order correlation function.</sec><sec>Our study shows that, the nonlinear photon term not only eliminates the energy spectral collapse but also makes it well-defined and complete in all the coupling regime. When at the resonance between the atomic and the field frequency, the nonlinear photon term breaks the harmonicity of the energy spectrum and produces a ladder of the excited number in the ground state. Because the larger nonlinear photon term inhibits the photon transition from an energy level to the higher one, it produces the single-photon projection state in the larger coupling region. Accordingly, we find that the nonlinear photon term promotes photon blockade by calculating the second-order correlation function. When at the non-resonant region, the nonlinear photon term enlarges the originally anharmonic energy ladder. For a complete BS model with the fixed nonlinear photon coupling strength and the fixed detuning, the energy level for the positive detuning is lower than that with the negative detuning, and more energy is required to overcome the absorption of a photon. Therefore, the positive detuning promotes the photon blockade. For the negative detuning, the system is more likely to absorb a photon and jump to a higher energy level, and therefore, suppresses the photon blockade.</sec>

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Numerical approach for the evolution of spin-boson systems and its application to the Buck–Sukumar model

Cited by 4 publications

References 36 publications

Charging performance of quantum batteries based on intensity-dependent Dicke model

Charging performance of quantum batteries based on intensity-dependent Dicke model

Density Operator Approach to Turbulent Flows in Plasma and Atmospheric Fluids

The photon blockade effect of a complete Buck-Sukumar model

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