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Bin Chen

Publications and source records attributed to Bin Chen.

820 records · Page 46Linked to original sources
arXiv1999

Quantum Theory for Mesoscopic Electric Circuits and Its Applications

This talk is assumed to exhibit an overview of the quantum theory for mesoscopic electric circuits and some of its further developments. In the theory the importance of the discreteness of electronic charge in mesoscopic electric circuit is addressed. The mesoscopic LC-design is quantized in accord with the charge discreteness. The uncertainty relation for electric charge and current is given. Because the stationary Schrödinger equation is turned to be Mathieu equation in $p$-representation, the wave function and energy spectrum is formally solved. As further applications, the persistent current is obtained by considering the mesoscopic ring as a pure L-design. The Coulomb blockade phenomenon occurs when applying the theory to the pure C-design. Concerning the time evolution of the states for mesoscopic electric circuit, we are able to study it by the method of characteristics. In order to study the dissipative effect in the circuit, we use density-matrix formulation. In this formulation, several type of ``off diagonal'' dissipations are expected to be discussed.

cond-mat.mes-hall↗
arXiv1999

Schwinger boson mean field theory of the Heisenberg Ferrimagnetic Spin Chain

The Schwinger boson mean field theory is applied to the quantum ferrimagnetic Heisenberg chain. There is a ferrimagnetic long range order in the ground state. We observe two branches of the low lying excitation and calculate the spin reduction, the gap of the antiferromagnetic branch, and the spin fluctuation at $T=0K$. These results agree with the established numerical results quite well. At finite temperatures, the long range order is destroyed because of the disappearance of the Bose condensation. The thermodynamic observables, such as the free energy, magnetic susceptibility, specific heat, and the spin correlation at $T>0K$, are calculated. The $Tχ_{uni}$ has a minimum at intermediate temperatures and the spin correlation length behaves as $T^{-1}$ at low temperatures. These qualitatively agree with the numerical results and the difference is small at low temperatures.

cond-mat.str-el↗
arXiv1999

The Effective Theory of Hole Doped Spin-1 Chain

An effective theory for the hole doped spin-1 antiferromagnetic chain is proposed in this paper. The two branches of low energy quasipaticle excitation is obtained by the diagrammic technique. In the large t limit(in which t is the hole hopping term), the lower band is essentially the bound state of one hole and one magnon and the other band is the sigle hole state. We find a critical value of t, $t_c=0.21Δ_H$(in which $Δ_H$ is the Haldane gap).For $t>t_c$, with the decrement of t, the mixing of these two bands become stronger and stronger, and at the same time the effective band mass becomes larger and larger. When $t<t_c$ the minimum of the lower band moves away from zero the another point between zero and $π/2$. The spin strcture factor is also calculated in this paper, and we find that for large t limit the main contribution is from the inter-band transition which induce a resonant peak in the Haldane gap. While for small t limit the main contribution is from the intra-band transition which only cause a diffusion like broad bump in the Haldan gap.

cond-mat.str-el↗
arXiv1996

Quantum theory for mesoscopic electric circuits

A quantum theory for mesoscopic electric circuits in accord with the discreteness of electric charges is proposed. On the basis of the theory, Schrödinger equation for the quantum LC-design and L-design is solved exactly. The uncertainty relation for electric charge and current is obtained and a minimum uncertainty state is solved. By introducing a gauge field, a formula for persistent current arising from magnetic flux is obtained from a new point of view.

cond-mat↗
arXiv1994

A Gauge Field Model On $SU(2)_L\times SU(2)_R\times U(1)_Y \times π_4(G_{YM})$

We reconstruct the Lagrangian of a left-right symmetric model with the gauge group $SU(2)_L\times SU(2)_R\times U(1)_Y \times π_4(SU(2)_L\times SU(2)_R\times U(1)_Y) $. The Higgs fields appear as gauge fields on discrete gauge group $π_4(SU(2)_L\times SU(2)_R\times U(1)_Y) $ and are assigned in a way complying with the principle that both the original gauge group $G_{YM}$ and the discrete group $π_4(G_{YM})$ should be taken as gauge groups in sense of non-commutative geometry.

hep-th↗
arXiv1994

Gauge theory on $Z_2 \times Z_2 \ti Z_2 $ Discrete Group and a Spontaneous $CP$ Violation Toy Model

In the spirit of Non-commutative differential calculus on discrete group, we construct a toy model of spontaneous $CP$ violation (SCPV). Our model is different from the well-known Weinberg-Branco model although it involves three Higgs doublets and preserve neutral flavor current conservation (NFC) after using the $Z_2 \ti Z_2 \ti Z_2$ discrete symmetry and imposing some constraints on Yukawa couplings.

hep-th↗
arXiv1994

A Gauge Field Model On $SU(2)_L\times SU(2)_R\times U(1)_Y \times π_4(G_{YM})$

We construct a gauge field model based on $SU(2)_L\times SU(2)_R\times U(1)_Y \times π_4(SU(2)_L\times SU(2)_R\times U(1)_Y) $ from the principle that both the original gauge group $G_{YM}$ and the discrete group $π_4(G_{YM})$ should be taken as gauge groups in the sense of non-commutative geometry. We show that the Yukawa coupling and the Higgs mechanism appear as natural results.

hep-ph↗
arXiv1994

Gravity and Discrete Symmetry

Using the differential calculus on discrete group, we study the general relativity in the space-time which is the product of a four dimensional manifold by a two-point space. We generalize the usual concept of frame and connection in our space-time, and from the generalized torsion free condition we obtain an action of a scalar field coupled to Einstein gravity, which may be related to the Jordan-Brans-Dicke theory.

hep-th↗