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Dung-Hai Lee

Publications and source records attributed to Dung-Hai Lee.

6 recordsLinked to original sources
PubMed2006

Abelian and non-abelian Hall liquids and charge-density wave: quantum number fractionalization in one and two dimensions.

Previously, we have demonstrated that, on a torus, the Abelian quantum Hall liquid is adiabatically connected to a charge-density wave as the smaller dimension of the torus is varied. In this work, we extend this result to the non-Abelian bosonic Hall state. The outcome of these works is the realization that the paradigms of quantum number fractionalization in one dimension (polyacetylene) and two dimensions (fractional quantum Hall effect) are, in fact, equivalent.

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PubMed2006

Stabilizing superconductivity in nanowires by coupling to dissipative environments.

We present a theory for a finite-length superconducting nanowire coupled to an environment. We show that in the absence of dissipation quantum phase slips always destroy superconductivity, even at zero temperature. Dissipation stabilizes the superconducting phase. We apply this theory to explain the "antiproximity effect" recently seen by Tian et al. in zinc nanowires.

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PubMed2005

Incompressible quantum liquids and new conservation laws.

In this Letter, we investigate a class of Hamiltonians which, in addition to the usual center-of-mass momentum conservation, also have center-of-mass position conservation. We find that, regardless of the particle statistics, the energy spectrum is at least q-fold degenerate when the filling factor is p/q, where and are coprime integers. Interestingly, the simplest Hamiltonian respecting this type of symmetry encapsulates two prominent examples of novel states of matter, namely, the fractional quantum Hall liquid and the quantum dimer liquid. We discuss the relevance of this class of Hamiltonian to the search for featureless Mott insulators.

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PubMed2004

Flux Period, Spin Gap, and Pairing in the One-Dimensional t-J-J' Model.

Using the factorization of the wave function in the t-J-J' model at small exchange couplings, we demonstrate the connection between the existence of a spin gap and an hc/2e flux periodicity of the ground state energy. We conjecture that all spin-gapped SU(2)-invariant Luttinger liquids have hc/2e flux periodicity, and that this is connected to the fact that a gapped spin-1/2 chain always breaks translational symmetry by doubling the unit cell.

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PubMed2004

Mott insulators without symmetry breaking.

We present theoretical models, in one and two space dimensions, that exhibit Mott insulating ground states at fractional occupations without any symmetry breaking. The Hamiltonians of these models are nonlocal in configuration space, but local in phase space.

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