Abstract:Aiming at the optimization of the spin diffusion length in (001) GaAs quantum wells, we explore the effect of the anisotropy of the spin-orbit coupling on the competition between the Rashba and the Dresselhaus spin-orbit couplings by solving the kinetic spin Bloch equations with the electronphonon and the electron-electron scattering explicitly included. For identical strengths of the Rashba and the Dresselhaus spin-orbit couplings, the spin diffusion length shows strong anisotropy not only for the spin polarization direction but also for the spin diffusion direction. Two special directions are used seeking for the large diffusion length: (110) and (110). Without the cubic term of the Dresselhaus spin-orbit coupling and with the identical Dresselhaus and Rashba strengths, infinite diffusion lengths can be obtained either for the spin diffusion/injection direction along (? 10), regardless of the direction of spin polarization, or for the spin polarization along (110), regardless of the direction of the spin diffusion/injection. However, the cubic Dresselhaus term cannot be neglected, resulting into a finite spin diffusion length which decreases with the temperature and the electron density, and of which the anisotropy for the spin diffusion direction and spin polarization direction is maintained. For the spin diffusion/injection direction along (?10), the spin diffusion length increases first with the increase of the Rashba strength (from 0) which can be tuned by the external gate voltage; when the Rashba strength is slightly smaller than (in stead of equal to) the Dresselhaus strength, the diffusion length reaches its maximum; and then it decreases with the Rashba strength.

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	1. Anisotropic spin transport in GaAs quantum wells in the presence of competing Dresselhaus and Rashba spin-orbit-coupling strengths
	J. L. Cheng,M. W. Wu,I. C. da Cunha Lima
	Physics 22 March 2007
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	Abstract:Aiming at the optimization of the spin diffusion length in (001) GaAs quantum wells, we explore the effect of the anisotropy of the spin-orbit coupling on the competition between the Rashba and the Dresselhaus spin-orbit couplings by solving the kinetic spin Bloch equations with the electronphonon and the electron-electron scattering explicitly included. For identical strengths of the Rashba and the Dresselhaus spin-orbit couplings, the spin diffusion length shows strong anisotropy not only for the spin polarization direction but also for the spin diffusion direction. Two special directions are used seeking for the large diffusion length: (110) and (110). Without the cubic term of the Dresselhaus spin-orbit coupling and with the identical Dresselhaus and Rashba strengths, infinite diffusion lengths can be obtained either for the spin diffusion/injection direction along (? 10), regardless of the direction of spin polarization, or for the spin polarization along (110), regardless of the direction of the spin diffusion/injection. However, the cubic Dresselhaus term cannot be neglected, resulting into a finite spin diffusion length which decreases with the temperature and the electron density, and of which the anisotropy for the spin diffusion direction and spin polarization direction is maintained. For the spin diffusion/injection direction along (?10), the spin diffusion length increases first with the increase of the Rashba strength (from 0) which can be tuned by the external gate voltage; when the Rashba strength is slightly smaller than (in stead of equal to) the Dresselhaus strength, the diffusion length reaches its maximum; and then it decreases with the Rashba strength.
	TO cite this article:J. L. Cheng,M. W. Wu,I. C. da Cunha Lima. Anisotropic spin transport in GaAs quantum wells in the presence of competing Dresselhaus and Rashba spin-orbit-coupling strengths[OL].[22 March 2007] http://en.paper.edu.cn/en_releasepaper/content/11593


	2. Temperature Sensitivity of Bushy Cells in Auditory Midbrain
	Zeng Ting,Wang Jiafu,Kuang Shenbing
	Physics 04 January 2007
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	Abstract:The temperature sensitivity of weak periodic signal detection has been studied via numerical simulations for bushy cells in auditory midbrain. The dependence of the spiking threshold of the signal upon its frequency and temperature could account for the temperature sensitivity. In the presence of the effect of frequency and temperature on the spiking threshold of the signal, our analyses reveal that there exists a temperature sensitivity range, and as the frequency of the signal decreasing, the sensitivity range is wider. These findings imply that there is a physiological temperature range which is benefit for the information processing in auditory system, and it processes the signal at lower frequency well in a wider temperature range than at higher frequency.
	TO cite this article:Zeng Ting,Wang Jiafu,Kuang Shenbing. Temperature Sensitivity of Bushy Cells in Auditory Midbrain[OL].[ 4 January 2007] http://en.paper.edu.cn/en_releasepaper/content/10583

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	3. The effect of the antiresonance on the I-V character
	Yu Liu,Yisong Zheng,Weijiang Gong
	Physics 12 September 2006
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	Abstract:The I-V spectrum of electronic transport through a quantum dot chain is calculated by means of the nonequilibrium Green function technique. In such a system, two arbitrary quantum dots are connected with two electron reservoirs through leads. When the dot-lead coupling is very weak, a series of discrete resonant peaks in electron transmission function cause staircase-like I-V characteristic. On the contrary, in the relatively strong dot-lead coupling regime, stairs in the I-V spectrum due to resonance vanish. However, when there are some dangling quantum dots in the chain outside two leads, the antiresonance which corresponds to the zero points of electron transmission function brings about novel staircase characteristic in the I-V spectrum. Moreover, two features in the I-V spectrum arising from the antiresonance are pointed out, which are significant for possible device applications. One is the multiple negative differential conductance regions, and another is regarding to create a highly spin-polarized current through the quantum dot chain by the interplay of the resonance and antiresonance. Finally, we focus on the role that the many-body effect plays on the antiresonance. Our result is that the antiresonance remains when the electron interaction is considered to the second order approximation.
	TO cite this article:Yu Liu,Yisong Zheng,Weijiang Gong. The effect of the antiresonance on the I-V character[OL].[12 September 2006] http://en.paper.edu.cn/en_releasepaper/content/8314


	4. Antiresonance in multi-quantum-dot system and its application as a spin filter
	Weijiang Gong,Yisong Zheng,Yu Liu,Wenzhu Gao
	Physics 28 August 2006
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	Abstract:By means of the nonequilibrium Green function technique, the electronic transport through a multi-quantum-dot system is theoretically studied. In this system, a one-dimensional quantum dot chain between two contacts forms a main channel for the electronic tunnelling. Each quantum dot in the chain couples laterally to a dangling quantum dot. Whenever the energy of the incident electron is aligned with the energy levels of the dangling quantum dots, a zero point of the electron transmission function occurs due to the Fano antiresonance. As a result, the linear conductance spectrum presents an insulating band around the antiresonant point. What is interesting is that both edges of the insulating band become steep rapidly with the increase of numbers of the quantum dots, and an energy gap comes up evidently. This phenomenon is discussed in detail, and is compared with the one-dimensional double quantum dot system, where one can realize the importance of the antiresonant effect. Therefore, we assume that the quantum dot levels are spin dependent, which can be realized by applying a magnetic field on them or assuming them to be made of ferromagnetic material. The energy gap corresponding to opposite spins can separate from each other. With regard to the intradot electron interaction, we assume the second-order approximation, and the energy gap broadens. On the basis of this feature, we propose that such a double-quantum-dot chain can be considered as a device prototype of a spin flter.
	TO cite this article:Weijiang Gong,Yisong Zheng,Yu Liu, et al. Antiresonance in multi-quantum-dot system and its application as a spin filter[OL].[28 August 2006] http://en.paper.edu.cn/en_releasepaper/content/8042


	5. Entanglement in a Quantum Mixed-Spin
	Hao Xiang,Zhu Shiqun
	Physics 21 April 2006
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	Abstract:The entanglement in a general mixed spin chain with arbitrary spin $S$ and $1/2$ is investigated in the thermodynamical limit. The entanglement is witnessed by the magnetic susceptibility which decides a characteristic temperature for an entangled thermal state. The characteristic temperature is nearly proportional to the interaction $J$ and the mixed spin $S$. The bound of negativity is obtained on the basis of the magnetic susceptibility. It is found that the macroscopic magnetic properties are affected by the quantum entanglement in the real solids. Meanwhile, the entanglement can be quantitatively evaluated by the thermodynamical observable.
	TO cite this article:Hao Xiang,Zhu Shiqun. Entanglement in a Quantum Mixed-Spin[OL].[21 April 2006] http://en.paper.edu.cn/en_releasepaper/content/6339


	6. A possible mechanism of current in medium under electromagnetic wave
	Zhang Tao
	Physics 04 April 2006
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	Abstract:A possible mechanism of current in medium was presented. Comparison between this current and the magnetization current was made. Expression for this current was derived. This work is helpful to the understanding of interaction between medium and electromagnetic wave.
	TO cite this article:Zhang Tao. A possible mechanism of current in medium under electromagnetic wave[OL].[ 4 April 2006] http://en.paper.edu.cn/en_releasepaper/content/6056


	7. Maxwell’s Equations in Medium
	Zhang Tao
	Physics 31 March 2006
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	Abstract:Reactions (magnetization, polarization, induced magnetization) of medium to electromagnetic wave and propagation of electromagnetic wave in medium were investigated. Faraday’s law in medium was presented, which is correct not only in vacuum but also in medium. The Maxwell’s Equations in medium was modified.
	TO cite this article:Zhang Tao. Maxwell’s Equations in Medium[OL].[31 March 2006] http://en.paper.edu.cn/en_releasepaper/content/6024


	8. Average Fidelity of Teleportation in Quantum Noise Channel
	Hao Xiang,Zhang Rong,Zhu Shiqun
	Physics 27 March 2006
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	Abstract:The effects of amplitude damping in quantum noise channels on average fidelity of quantum teleportation are analyzed in Bloch sphere representation for every stage of teleportation. When the quantum channels are varied from maximally entangled states to non-maximally entangled states, it is found that the effects of noise channels on the fidelity are nearly equivalent for strong quantum noise. The degree of damage on the fidelity of non-maximally entangled channels is smaller than that of maximally entangled channels. The average fidelity of values larger than $2\!/3$ may be one representation indirectly showing how much the unavoidable quantum noise is.
	TO cite this article:Hao Xiang,Zhang Rong,Zhu Shiqun. Average Fidelity of Teleportation in Quantum Noise Channel[OL].[27 March 2006] http://en.paper.edu.cn/en_releasepaper/content/5920


	9. Deduction of Initial Strategy Distributions of Agents in Mix-game Model
	Gou Chengling
	Physics 10 March 2006
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	Abstract:This paper reports the effort of deducing the initial strategy distributions of agents in mix-game model which is used to predict a real financial time series generated from a target financial market. Using mix-game to predict Shanghai Index, we find the time series of prediction accurate rates is sensitive to the initial strategy distributions of agents in group 2 who play minority game, but less sensitive to the initial strategy distributions of agents in group 1 who play majority game. And agents in group 2 tend to cluster in full strategy space (FSS) if the real financial time series has obvious tendency (upward or downward), otherwise they tend to scatter in FSS. We also find that the initial strategy distributions and the number of agents in group 1 influence the level of prediction accurate rates. Finally, this paper gives suggestion about further research.
	TO cite this article:Gou Chengling. Deduction of Initial Strategy Distributions of Agents in Mix-game Model [OL].[10 March 2006] http://en.paper.edu.cn/en_releasepaper/content/5634


	10. Quasinormal modes of the Schwarzschild black hole with arbitrary spin fields
	Qiyuan Pan,Jiliang Jing
	Physics 27 February 2006
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	Abstract:The quasinormal modes (QNMs) associated with the decay of massless arbitrary spin fields around a Schwarzschild black hole are investigated by using the continued fraction method in a united form and their universal properties are found. It is shown that these QNMs become evenly spaced for large angular quantum number $l$ (for the boson perturbations) and $j$ (for the fermion perturbations) and the spacing is independent of the spin number $s$ and overtone number $n$, and in the complex plane they have an interesting trend which depends on $n$ before they become the same value with the increasing $l$ (or $j$). It is also shown that the angular quantum number has the surprising effect of increasing real part of the QNMs, but it almost does not affect imaginary part, especially for the lowest lying mode. In addition, the spacing for imaginary part of the QNMs at high overtones is equidistant and equals to $-i/4M$, which is independent of $l$ (or $j$) and $s$.
	TO cite this article:Qiyuan Pan,Jiliang Jing. Quasinormal modes of the Schwarzschild black hole with arbitrary spin fields [OL].[27 February 2006] http://en.paper.edu.cn/en_releasepaper/content/5393

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