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Dynamic Behaviour of Vortex Matter, Memory Effect and Mittag--Leffler Relaxation

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Chinese Physics Letters 2001年第2期18卷 269-271页

作者： LIU Gang han ru-Shan Department of Physics Peking UniversityBeijing 100871 China Institute of Atomic Energy P.O.Box 275(18)Beijing 102413

Using fractional Fokker-Planck equation and Langevin equation's Monte Carlo simulation,we find that when current density is less than critical current density,at the very beginning the motion for vortices is mainly within the pinning well with the typical relaxation time *** time t is longer than Tr,the vortex glass will distort between two adjacent pining wells and will lead to memory effect which is lacking in the Mott insulator and pancake *** inertial effect is not dominating as compared with the formation and growth of easy-flow *** random quenched disorder will lead to Mittag-Leffler relaxation.

关键词： equation relaxation vortex

Theoretical Calculation for the Dip Feature in Tunnelling Experiment on Bi2212

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Chinese Physics Letters 2001年第9期18卷 1256-1257页

作者： XIE Gang han ru-Shan Mesoscopic Physics Laboratory and Department of Physics Peking UniversityBeijing 100871

We generalize a model, which was presented by Norman [Phys. Rev. Lett. 79 (1997) 3506], to calculate the Bi2Sr2CaCu2Os+δ (Bi2212) single-electron tunnelling conductance. In our calculation result, the dip feature appears which has been widely observed in tunnelling experiments. It is found that this dip feature in tunnelling experiments and the dip/hump feature in angle-resolved photoemission experiments have a common physics. Moreover, it is shown from our numerical calculation method that if the spectral function A(κ, ω) is known, the tunnelling conductance can be obtained.

关键词： conductance Bi2212 calculation

Electron Spin Pairing and the Phase Diagram of High-Tc Superconductors

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Chinese Physics Letters 2001年第10期18卷 1398-1400页

作者： GUO Wei han ru-Shan Department of Physics Peking UniversityBeijing 100871

The origin of the instability of the normal state of electrons in the superconducting copper oxides is shown by the K-J model, in which the superexchange (K) between local moments and the Kondo exchange ( J) between electron and local moment are considered. The suppression of superexchange via impurity doping may induce effective spin coupling between electrons and triplet pairing (S = 1, Sz = 0). The spin pairing theory explains the phase diagram of high-To superconductors, especially the superconducting transition temperature Tc, the pseudogap temperature T^(*) and the magnetic crossover temperature Tn as a function of the doped hole concentration. The universal expression for the empirical law of the superconducting transition temperature is derived from the theory.

关键词： theory exchange Electron

The Physical Property of Susceptibility for One-Dimensional Ferrimagnetic Chain with Alternating Spins 1 and 1/2 in Finite Magnetic Field

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Communications in Theoretical Physics 2001年第11期36卷 620-622页

作者： XIE Gang han ru-Shan Mesoscopic Physics Lab and Department of Physics Peking UniversityBeijing 100871China Mesoscopic Physics Lab and Department of PhysicsPeking UniversityBeijing 100871China

We further calculate the dependence of xT on T in high magnetic fields,where X denotes susceptibility and T is temperature,using our previous research work - Green function's decoupling approximate approach,for the one-dimensional ferrimagnetic chain with alternating spins 1 and 1/*** find a linear correlation in certain range of magnetic field between the temperature of xT maximum and the magnetic ***,we simply analyze its physical meaning by our approach.

关键词： one-dimensional spin chain,susceptibility,ferrimagnetic,Green function

Time-Reversal Symmetry Breaking: an Evidence for Spin Pairing in High-T_(c) Superconductors

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Chinese Physics Letters 2001年第4期18卷 582-583页

作者： GUO Wei han ru-Shan Department of Physics Peking UniversityBeijing 100871

Effective spin coupling leads to local triplet pairing in the antiferromagnetically ordered CuO2 plane as shown by the K-J model[Guo et ***.18(2001)103].The precession of the spin triplet(S=1,Sz=0)in the CuO2 plane does not hold time-reversal invariance due to the dimpled CuO structure,which not only modifies the gap function but also contributes to the asymmetry of the high-Tc tunneling *** principle,the effect of time-reversal symmetry breaking can be manifested by the variation of the conductance asymmetry by applying a magnetic field at superconductor-insulator-normal metal junction,which should provide a direct evidence for triplet pairing in the high-Tc superconductors.

关键词： conductance superconductor breaking

Constraint Symbolization Method for Analog Layout Retargeting with Geometric Programming

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Chinese Journal of Electronics 2014年第1期23卷 65-69页

作者： WANG Shaoxi FAN Xiaoya ZhanG Shengbing han ru School of Software and Microelectronics Northwestern Polytechnical University

To satisfy the requirements of complex and special analog layout constraints, a constraint symbolization method based on geometric programming for analog layout retargeting is presented in this paper. Our approach is to build symbolic template for layouts, then uses Geometric programming(GP) to achieve new technology design rules, implement device symmetry and matching constraints, and manage parasitics optimization. The GP,a class of non-linear optimization problem, can be transferred or fitted into a convex optimization problem. Therefore, a global optimum solution can be achieved. The symbolization method ensures the layout retargeting automatically. The efficiency and effectiveness of the proposed algorithm, as compared with the other existing methods, are demonstrated by a basic case-study example and a twostage Miller-compensated operational amplifier.

关键词： Constraint symbolization Geometric programming Layout Retargeting

Symbolic Reasoning About Quantum Circuits in Coq

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Journal of Computer Science & Technology 2021年第6期36卷 1291-1306页

作者： Wen-Jun Shi Qin-Xiang Cao Yu-Xin Deng han-ru Jiang Yuan Feng Shanghai Key Laboratory of Trustworthy Computing East China Normal UniversityShanghai 200062China John Hopcroft Center of Computer Science Shanghai Jiao Tong UniversityShanghai 200240China Yanqi Lake Beijing Institute of Mathematical Sciences and Applications Beijing 101408China Centre for Quantum Software and Information University of Technology SydneySydney NSW 2007Australia

A quantum circuit is a computational unit that transforms an input quantum state to an output state.A natural way to reason about its behavior is to compute explicitly the unitary matrix implemented by ***,when the number of qubits increases,the matrix dimension grows exponentially and the computation becomes *** this paper,we propose a symbolic approach to reasoning about quantum *** is based on a small set of laws involving some basic manipulations on vectors and *** symbolic reasoning scales better than the explicit one and is well suited to be automated in Coq,as demonstrated with some typical examples.

关键词： quantum circuit symbolic reasoning Dirac notation Coq

Optimization of ambipolar current and analog/RF performance for T-shaped tunnel field-effect transistor with gate dielectric spacer

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Chinese Physics B 2019年第1期28卷 656-662页

作者： ru han Hai-Chao Zhang Dang-Hui Wang Cui Li School of Computer Science and Engineering Northwestern Polytechnical University

A new T-shaped tunnel field-effect transistor(TTFET) with gate dielectric spacer(GDS) structure is proposed in this paper. To further studied the effects of GDS structure on the TTFET, detailed device characteristics such as current-voltage relationships, energy band diagrams, band-to-band tunneling(BTBT) rate and the magnitude of the electric field are investigated by using TCAD simulation. It is found that compared with conventional TTFET and TTFET with gate-drain overlap(GDO) structure, GDS-TTFET not only has the minimum ambipolar current but also can suppress the ambipolar current under a more extensive bias range. Furthermore, the analog/RF performances of GDS-TTFET are also investigated in terms of transconductance, gate-source capacitance, gate-drain capacitance, cutoff frequency, and gain bandwidth production. By inserting a low-κ spacer layer between the gate electrode and the gate dielectric, the GDS structure can effectively reduce parasitic capacitances between the gate and the source/drain, which leads to better performance in term of cutoff frequency and gain bandwidth production. Finally, the thickness of the gate dielectric spacer is optimized for better ambipolar current suppression and improved analog/RF performance.

关键词： tunneling field effect transistor T-shaped tunnel field-effect transistor gate dielectric spacer ambipolar current analog/RF performance

Effect of Sample Thickness on Magneto-Optic Imaging for Vortex Fully Penetrated Square-Shaped Superconductors

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Chinese Physics Letters 1998年第1期15卷 65-67页

作者： LIU Yun GAO Zheng-xiang TAO Jing han ru-shan Department of Physics Peking UniversityBeijing 100871

A significant effect of sample thickness on three components of the magnetic flux density distribution on square-shaped superconductor surface is shown,and the critical current density jc of the superconductor from th... 详细信息

关键词： superconductor Vortex Superconductor