arXiv subjects

Qi-Xuan Wu

Publications and source records attributed to Qi-Xuan Wu.

9 recordsLinked to original sources

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".

quant-ph↗

arXiv2024

Effect of Spontaneously Generated Coherence and Detuning on 2D Atom Localization in Two Orthogonal Standing-Wave Fields

Two-dimensional (2D) atom localization via the spontaneously generated coherence (SGC) and detunings associated with the probe and standing-wave driving fields in a three-level V-type atomic system are investigated. In the gain process, two equal and tunable peak maxima of position distribution in the plane via the detunings are observed. However, one decreasing and the other increasing peak maxima in the absorption process via the SGC are achieved in the quadrants I and III of the x-y plane. A better resolution and more novelty for the 2D atom localization in our scheme are obtained.

quant-ph↗

arXiv2024

Left-handedness with three zero-absorption windows tuned by the incoherent pumping field and inter-dot tunnelings in a GaAs/AlGaAs triple quantum dots system

Left-handedness with three zero-absorption windows is achieved in a triple-quantum dot (TQD) system. With the typical parameters of a GaAs/AlGaAs heterostructure, the simultaneous negative relative electric permittivity and magnetic permeability are obtained by the adjustable incoherent pumping field and two inter-dot tunnelings. What's more, three zero-absorption windows in the left-handedness frequency bands are observed in the TQD system. The left-handedness with zero-absorption in solid state heterostructure may solve not only the challenge in the photonic resonant scheme for left-handed materials (LHMs) but also the application limitation of the negative refractive materials with large amount of absorption.

quant-ph↗

arXiv2024

2-D isotropic negative refractive index in a N-type four-level atomic system

2-D(Two-dimensional) isotropic negative refractive index (NRI) is explicitly realized via the orthogonal signal and coupling standing-wave fields coupling the N-type four-level atomic system. Under some key parameters of the dense vapor media, the atomic system exhibits isotropic NRI with simultaneous negative permittivity and permeability (i.e. Left-handedness) in the 2-D x-y plane. Compared with other 2-D NRI schemes, the coherent atomic vapor media in our scheme may be an ideal 2-D isotropic NRI candidate and has some potential advantages, significance or applications in the further investigation.

quant-ph↗

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.

quant-ph↗

arXiv2024

Algebraic analysis of electromagnetic chirality-induced negative refractive index in a four-level atomic system

This paper presents a algebraic analysis of electromagnetic chirality-induced negative refractive index in a four-level atomic medium. According to analyze mathematically its argument of the complex refractive index for one circular polarization, it found that the negative refractive index without simultaneously negative permittivity and permeability can be obtained when the argument is in the second quadrant of the cartesian coordinate system, and that the probe field coupling to two equal transition frequencies in the atomic level doesn't require. This undoubtedly reduced stringent conditions to negative refractive index by quantum optics. As an application, our scheme may possibly give a novel approach to obtain negative refractive index by electromagnetic chirality-inducing.

quant-ph↗

arXiv2024

High quantum yields generated by a multi-band quantum dot photocell

We perform the quantum yields in a multi-band quantum dot (QD) photocell via doping an intermediate band (IB) between the conduction band (CB) and valence band (VB). Under two different sub-band gap layouts, the output power has a prominent enhancement than the single-band gap photocell and the achieved peak photo-to-charge efficiency reaches to 74.9% as compared to the limit efficiency of 63.2% via the IB approach in the theoretical solar cell prototype. The achieved quantum yields reveal the potential to improve efficiency by some effective theoretical approaches in the QD-IB photocell.

cond-mat.mes-hall↗

arXiv2018

Wider frequency domain for negative refraction index in a quantized composite right-left handed transmission line

The refraction index of the quantized lossy composite right-left handed transmission line (CRLH-TL) is deduced in the thermal coherence state. The results show that the negative refraction index (herein the left-handedness) can be implemented by the electric circuit dissipative factors(i.e., the resistances \(R\) and conductances \( G\)) in a higher frequency band (1.446GHz\(\leqω\leq \) 15GHz), and flexibly adjusted by the left-handed circuit components (\(C_l\), \(L_l\)) and the right-handed circuit components (\(C_r\), \(L_r\)) at a lower frequency (\(ω\)=0.995GHz) . The flexible adjustment for left-handedness in a wider bandwidth will be significant for the microscale circuit design of the CRLH-TL and may make the theoretical preparation for its compact applications.

physics.app-ph↗

arXiv2017

Negative refraction index of the quantum lossy left-handed transmission lines affected by the displaced squeezed Fock state and dissipation

Quantum lossy left-handed transmission lines (LHTLs) are central to the miniaturized application in microwave band. This work discusses the NRI of the quantized lossy LHTLs in the presence of the resistance and the conductance in a displaced squeezed Fock state (DSFS). And the results show some novel specific quantum characteristics of NRI caused by the DSFS and dissipation, which may be significant for its miniaturized application in a suit of novel microwave devices.

cond-mat.mes-hall↗