arXiv subjects

Chyh-Hong Chern

Publications and source records attributed to Chyh-Hong Chern.

25 records · Page 2Linked to original sources

arXiv2007

New family of models for incompressible quantum liquids in $d\geq 2$

Through Haldane's construction, the fractional quantum Hall states on a two-sphere was shown to be the ground states of {\it one-dimensional} SU(2) spin Hamiltonians. In this Letter we generalize this construction to obtain a new class of SU(N) spin Hamiltonians. These Hamiltonians describes center-of-mass-position conserving pair hopping fermions in space dimension $d\ge 2$. We conjecture that the excitations of these models posses fractional fermion number.

cond-mat.str-el↗

arXiv2007

Quantum charge pumping and electric polarization in Anderson insulators

We investigate adiabatic charge pumping in disordered system in one dimension with open and closed boundary conditions. In contrast to the Thouless charge pumping, the system has no gap even though all the states are localized, i.e., strong localization. Charge pumping can be achieved by making a loop adiabatically in the two-dimensional parameter space of the Hamiltonian. It is because there are many $δ$-function-like fluxes distributed over the parameter space with random strength, in sharp contrast to the single $δ$-function in the pure case. This provides a new and more efficient way of charge pumping and polarization.

cond-mat.dis-nn↗

arXiv2006

Enhanced dielectric response by disordered nanoscale/mesoscopic insulators

Enhancement of the dielectric response of insulators by disorder is theoretically proposed, where the quantum interference of electronic waves through the nanoscale/mesoscopic system and its change due to external perturbations control the polarization. In the disordered case with all the states being localized, the resonant tunneling, which is topologically protected, plays a crucial role, and enhances the dielectric response by a factor 30~40 compared with the pure case. Realization of this idea with accessible materials/structures is also discussed.

cond-mat.mes-hall↗

arXiv2006

Theory of Four-dimensional Fractional Quantum Hall States

We propose a pseudo-potential Hamiltonian for the Zhang-Hu's generalized fractional quantum Hall states to be the exact and unique ground states. Analogously to Laughlin's quasi-hole (quasi-particle), the excitations in the generalized fractional quantum Hall states are extended objects. They are vortex-like excitations with fractional charges $+(-)1/m^3$ in the total configuration space CP$^3$. The density correlation function of the Zhang-Hu states indicates that they are incompressible liquid.

cond-mat.str-el↗

arXiv2005

The generalized equation of motion for the orbital dynamics in the presence of current

The orbital dynamics induced by the charge current is studied theoretically. The equation of motion for the isospin vector $T^A$ in the SU(N) case is derived in the presence of the current, and is applied to the cases of $e_g$ (N=2) and $t_{2g}$ (N=3) orbitals. In spite of the anisotropic transfer integrals between orbitals, the dynamics is found to be isotropic for $e_g$-orbitals similarly to the spin case, while it is anisotropic for $t_{2g}$-orbitals. The implication of this result to the current driven orbital domain wall motion is discussed.

cond-mat.str-el↗

arXiv2004

Non-abelian Berry's phase and Chern numbers in higher spin pairing condensates

We show that the non-Abelian Berry phase emerges naturally in the s-wave and spin quintet pairing channel of spin-3/2 fermions. The topological structure of this pairing condensate is characterized by the second Chern number. This topological structure can be realized in ultra-cold atomic systems and in solid state systems with at least two Kramers doublets.

cond-mat.supr-con↗

arXiv2002

Effective field theory description of the higher dimensional quantum Hall liquid

We derive an effective topological field theory model of the four dimensional quantum Hall liquid state recently constructed by Zhang and Hu. Using a generalization of the flux attachment transformation, the effective field theory can be formulated as a U(1) Chern-Simons theory over the total configuration space $CP_3$, or as a SU(2) Chern-Simons theory over $S^4$. The new quantum Hall liquid supports various types of topological excitations, including the 0-brane (particles), the 2-brane (membranes) and the 4-brane. There is a topological phase interaction among the membranes which generalizes the concept of fractional statistics.

cond-mat↗