arXiv subjects

Zheng-Dong Liu

Publications and source records attributed to Zheng-Dong Liu.

5 recordsLinked to original sources

arXiv2026

Negative refraction with low absorption using EIT in a four-level left-handed atomic system

We suggest a scheme for obtaining negative refraction with low absorption in a left-handed atomic system.Under the the appropriate conditions,the atomic system displays negative refraction with negative permittivity and permeability(Left-handedness)in a common frequency range,simultaneously.And the imaginary parts of permittivity and permeability show transparently propagate in the same frequency range.Finally,the negative refraction show low absorption due to the EIT effect,and the figure of merit demonstrated this in this resonant atomic system.

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arXiv2024

Left-handedness without absorption in the four-level Y-type atomic medium

In this paper,three external fields interacting with the four-level Y-type atomic system described by the density-matrix approach is investigated .The results show that the left-handedness with zero absorption are achieved.And the zero absorption property displays the possibility of manipulation with varying the phase and the intensity of the coupling field. The zero absorption property may be used to amplify the evanescent waves that have been lost in the imaging by traditional lenses.Our scheme proposes an approach to obtain negative refractive medium with zero absorption and the possibility to enhance the imaging resolution in realizing "superlenses".

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arXiv2024

Electromagnetic chirality-induced negative refraction with the same amplitude and anti-phase of the two chirality coefficients

We suggest a scheme of electromagnetic chirality-induced negative refraction utilizing magneto-electric cross coupling in a four-level atomic system. The negative refraction can be achieved with the two chirality coefficients having the same amplitude but the opposite phase,and without requiring the simultaneous presence of an electric-dipole and a magnetic-dipole transition near the same transition frequency. The simultaneously negative electric permittivity and magnetic permeability does not require, either.

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arXiv2024

Manipulative Properties of the Asymmetry Double Quantum Dots via Laser and Gate Voltage

We present the density matrix approach for theoretical description of an asymmetric double quantum dot(QD)system.The results show that the properties of gain,absorption and dispersion of the double QD system ,the population of the state with one hole in one dot and an electron in other dot transferred by tunneling can be manipulated by the laser pulse or gate voltage.Our scheme may propose a probability of electro-optical manipulation of quantum system.

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arXiv2024

Negative refraction without absorption via both coherent and incoherent fields in a four-level left-handed atomic system

This paper attempts a probe into negative refraction without absorption by means of an incoherent pump field and a strong coherent field coupling the dense four-level atomic system.With the application of the incoherent pump field to manipulate the populations in atomic levels and the variable strong coherent field to create quantum coherence, the constraint condition of two equal transition frequencies responding to the probe field in the atomic system isn't required.And these lead to the propagation transparency and strong magnetic response of the probe field,left-handedness with vanishing absorption in the atomic system.However,an excessive coherent field intensity would increase the absorption.

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