Showing papers by "Jinwu Ye published in 2006"

Ginzburg-Landau theory of a supersolid.

Abstract: We develop a simple Ginsburg-Landau theory to study all the possible phases and phase transitions in {sup 4}He, analyze the condition for the existence of the supersolid (SS) and map out its global phase diagram from a unified framework. If the condition favors the existence of the SS, we use the GL theory to address several experimental facts and also make some predictions that are amenable to experimental tests. A key prediction is that the x-ray scattering intensity from the SS ought to have an additional modulation over that of the normal solid. The modulation amplitude is proportional to the nonclassical rotational-inertial observed in the torsional oscillator experiments.

Fractional charges and quantum phase transitions in imbalanced bilayer quantum Hall systems.

Abstract: We extend the composite boson theory to study slightly imbalanced bilayer quantum Hall systems. In the global $U(1)$ symmetry breaking excitonic superfluid side, as the imbalance increases, the system supports continuously changing fractional charges. In the translational symmetry breaking pseudospin density wave (PSDW) side, there are two quantum phase transitions from the commensurate PSDW to an incommensurate PSDW and then to the excitonic superfluid state. We compare our theory with experimental data and also the previous microscopic calculations.

Ground state, quasihole, a pair of quasihole wave functions, and instability in bilayer quantum Hall systems

Abstract: The bilayer quantum Hall system (BLQH) differs from its single layer counterparts (SLQH) by its symmetry breaking ground state and associated neutral gapless mode in the pseudospin sector. Due to the gapless mode, qualitatively good ground-state and low energy excited-state wave functions at any finite distance are still unknown. We investigate this important open problem by the composite boson (CB) theory developed by one of the authors to study BLQH systematically. We derive the ground state, quasihole, and a pair of quasihole wave functions from the CB theory and its dual action. We find that the ground-state wave function is the product of two parts, one in the charge sector which is the well known Halperin (111) wave function and the other in the spin sector which is nontrivial at any finite $d$ due to the gapless mode. So the total ground-state wave function differs from the well known (111) wave function at any finite $d$. In addition to commonly known multiplicative factors, the quasihole and a pair of quasihole wave functions also contain nontrivial normalization factors multiplying the correct ground state wave function. We expect that the quasihole and pair wave function not only has logarithmically divergent energy and well localized charge distribution, but also correct interlayer correlations. All the distance dependencies in all the wave functions are encoded in the spin part of the ground-state wave function. The instability encoded in the spin part of the ground-state wave function leads to the pseudo-spin-density wave proposed by one of the authors previously. Some subtleties related to the Lowest Landau Level (LLL) projection and shortcomings of the CB theory are also noted.