Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

2019 ( 54 )

2018 ( 446 )

2017 ( 433 )

2016 ( 396 )

Custom range...

Search Results: 1 - 10 of 29063 matches for " TAN Zeng-qiang "
All listed articles are free for downloading (OA Articles)
Page 1 /29063
Display every page Item
Phase transitions and elementary excitations in spin-1 Bose gases with Raman induced spin-orbit coupling
Zeng-Qiang Yu
Physics , 2015,
Abstract: We study the ground state phase diagram and the quantum phase transitions in spin-1 Bose gases with Raman induced spin-orbit coupling. In addition to the Bose-Einstein condensates with uniform density, three types of stripe condensation phases that simultaneously break the U(1) and the translation symmetry are identified in presence of spin-dependent interactions. The transitions between these phases are characterized by the spin magnetization and different crystalline orders, and the occurrences of the various tricritical points are predicted. The excitation spectra in the plane-wave phase and the zero-momentum phase show rich roton-maxon structures, and their instabilities indicate the tendency to develop crystalline orders. We propose the atomic gas of $^{23}$Na could be a candidate for observing the stripe condensate with high contrast fringes.
Equation of state and phase transition in spin-orbit-coupled Bose gases at finite temperature: A perturbation approach
Zeng-Qiang Yu
Physics , 2014, DOI: 10.1103/PhysRevA.90.053608
Abstract: We study two-component Bose gases with Raman induced spin-orbit coupling via a perturbation approach at finite temperature. For weak coupling, free energy is expanded in terms of Raman coupling strength up to the second order, where the coefficient (referred to as Raman susceptibility) is determined according to linear response theory. The equation of state for the stripe phase and the plane-wave phase are obtained in Popov approximation, and the first order transition between these two phases is investigated. As temperature increases, we find the phase boundary bends toward the stripe phase side in most temperature regions, which implies the ferromagnetic order is more robust than the crystalline order in presence of thermal fluctuations. Our results qualitatively agree with the recent experimental observation in rubidium atomic gases. A method to measure the Raman susceptibility through the two-photon Bragg scattering experiment is also discussed.
Ground-state phase diagram and critical temperature of two-component Bose gases with Rashba spin-orbit coupling
Zeng-Qiang Yu
Physics , 2013, DOI: 10.1103/PhysRevA.87.051606
Abstract: Ground-state phase diagram of two-component Bose gases with Rashba spin-orbit coupling is determined via a variational approach. A phase in which the fully polarized condensate occupies zero momentum is identified. This zero-momentum phase competes with the spin density wave phase when interspecies interaction is stronger than intraspecies interaction, and the former one is always the ground state for weak spin-orbit coupling. When the energies of these two phases are close, there is a phase separation between them. At finite temperature, such a zero-momentum condensation can be induced by a ferromagnetic phase transition in normal state. The spontaneous spin polarization removes the degeneracy of quasiparticles' energy minima, and consequently the modified density of state accommodates a Bose condensation to appear below a critical temperature.
Single Nucleotide Polymorphisms of PIN1 Promoter Region and Cancer Risk: Evidence from a Meta-Analysis
Jing-Jing Peng, Dong Wei, Dong Li, Zeng-Qiang Fu, Yong Tan, Tao Xu, Jing-Jun Zhou, Tao Zhang
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0070990
Abstract: Background Peptidylprolyl cis/trans isomerase NIMA-interacting 1 (PIN1) is involved in the process of tumorigenesis. The two single nucleotide polymorphisms (?677T>C, ?842G>C) in the PIN1 promoter region have been suspected of being associated with cancer risk for years, but the conclusion is still inconclusive. Methods Eligible case-control studies were retrieved by searching databases and references of related reviews and studies. Genotype distribution data, adjusted odds ratios (ORs) and 95% confidence (CIs) intervals were extracted to calculate pooled ORs. Results A total of 4619 cancer cases and 4661 controls were included in this meta-analysis. Overall, the PIN1 ?667T>C polymorphism was not associated with cancer risk, while the ?842C allele was significantly associated with reduced cancer risk (CC+GC vs. GG, OR = 0.725, 95% CI: 0.607–0.865; Pheterogeneity = 0.012 and GC vs. GG: OR = 0.721, 95% CI: 0.591–0.880; Pheterogeneity = 0.003). Results from genotype distribution data were in agreement with those calculated with adjusted ORs and 95% CIs. No publication bias was detected. Conclusions Results of this meta-analysis suggest that the PIN1 ?842G>C polymorphism is associated with decreased cancer risk, but that the ?667T>C polymorphism is not.
Low dimensional chaos in the AT and GC skew profiles of DNA sequences

Zhou Qian,Chen Zeng-Qiang,

中国物理 B , 2010,
Abstract: This paper investigates the existence of low-dimensional deterministic chaos in the AT and GC skew profiles of DNA sequences. It has taken DNA sequences from eight organisms as samples. The skew profiles are analysed using continuous wavelet transform and then nonlinear time series methods. The invariant measures of correlation dimension and the largest Lyapunov exponent are calculated. It is demonstrated that the AT and GC skew profiles of these DNA sequences all exhibit low dimensional chaotic behaviour. It suggests that chaotic properties may be ubiquitous in the DNA sequences of all organisms.
Collinear antiferromagnetic state in a two-dimensional Hubbard model at half filling
Zeng-Qiang Yu,Lan Yin
Physics , 2010, DOI: 10.1103/PhysRevB.81.195122
Abstract: In a half-filled Hubbard model on a square lattice, the next-nearest-neighbor hopping causes spin frustration, and the collinear antiferromagnetic (CAF) state appears as the ground state with suitable parameters. We find that there is a metal-insulator transition in the CAF state at a critical on-site repulsion. When the repulsion is small, the CAF state is metallic, and a van Hove singularity can be close to the Fermi surface, resulting in either a kink or a discontinuity in the magnetic moment. When the on-site repulsion is large, the CAF state is a Mott insulator. A first-order transition from the CAF phase to the antiferromagnetic phase and a second-order phase transition from the CAF phase to the paramagnetic phase are obtained in the phase diagram at zero temperature.
Molecular Bose-Einstein condensation in a Bose gas with a wide Feshbach resonance at finite temperatures
Zeng-Qiang Yu,Lan Yin
Physics , 2010, DOI: 10.1103/PhysRevA.81.023613
Abstract: Bose-Einstein condensation (BEC) of Feshbach molecules in a homogeneous Bose gas is studied at finite temperatures in a single-channel mean-field approach where the Hartree-Fock energy and pairing gap are determined self-consistently. In the molecular-BEC state, the atomic excitation is gapped and the molecular excitation is gapless. The binding energy of Feshbach molecules is shifted from the vacuum value due to many-body effect. When the scattering length $a_s$ of atoms is negative, the system is subject to mechanical collapse due to negative compressibility. The system is stable in most regions with positive scattering lengths. However at low temperatures near the resonance, the molecular-BEC state vanishes, and the coherent mixture of atomic and molecular BEC is subject to mechanical collapse.
Induced interaction in a spin-polarized Fermi gas
Zeng-Qiang Yu,Lan Yin
Physics , 2010, DOI: 10.1103/Phys.Rev.A82.013605
Abstract: We study the effect of the induced interaction on the superfluidtransition temperature of a spin-polarized Fermi gas. In the BCS limit, the polarization is very small in the superfluid state, and the effect of the induced interaction is almost the same as in the spin-balanced case. The temperature Tt and the polarization Pt of the tricritical point are both reduced from mean-field results by a factor about 2.22. This reduction is also significant beyond the BCS limit. In the unitary limit, we find (Pt,Tt/TF)=(0.42,0.16), in comparison with mean-field and experimental results.
Spin-Orbit Coupled Fermi Gases across a Feshbach Resonance
Zeng-Qiang Yu,Hui Zhai
Physics , 2011, DOI: 10.1103/PhysRevLett.107.195305
Abstract: In this letter we study both ground state properties and the superfluid transition temperature of a spin-1/2 Fermi gas across a Feshbach resonance with a synthetic spin-orbit coupling, using mean-field theory and exact solution of two-body problem. We show that a strong spin-orbit coupling can significantly enhance the pairing gap for 1/(k_F a_s)<=0 due to increased density-of-state. Strong spin-orbit coupling also significantly enhances the superfluid transition temperature when 1/(k_F a_s)<=0, while suppresses it slightly when 1/(k_F a_s)>0. The universal interaction energy and pair size at resonance are also discussed.
The induced interaction in a Fermi gas with a BEC-BCS crossover
Zeng-Qiang Yu,Kun Huang,Lan Yin
Physics , 2009, DOI: 10.1103/PhysRevA.79.053636
Abstract: We study the effect of the induced interaction on the superfluid transition temperature of a Fermi gas with a BEC-BCS crossover. The Gorkov-Melik-Barkhudarov theory about the induced interaction is extended from the BCS side to the entire crossover, and the pairing fluctuation is treated in the approach by Nozi\`{e}res and Schmitt-Rink. At unitarity, the induced interaction reduces the transition temperature by about twenty percent. In the BCS limit, the transition temperature is reduced by a factor about 2.22, as found by Gorkov and Melik-Barkhudarov. Our result shows that the effect of the induced interaction is important both on the BCS side and in the unitary region.
Page 1 /29063
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.