Gao Xianlong
Zhejiang Normal University
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Publication
Featured researches published by Gao Xianlong.
Physical Review B | 2008
Wei Li; Gao Xianlong; Corinna Kollath; Marco Polini
Time-dependent density-functional theory (TDDFT) is a powerful tool to study the non-equilibrium dynamics of inhomogeneous interacting many-body systems. Here we show that the simple adiabatic local-spin-density approximation for the time-dependent exchange-correlation potential is surprisingly accurate in describing collective density and spin dynamics in strongly correlated one-dimensional ultracold Fermi gases. Our conclusions are based on extensive comparisons between our TDDFT results and accurate results based on the adaptive time-dependent density-matrix renormalization-group method.
Physical Review Letters | 2008
Gao Xianlong; Marco Polini; Diego Rainis; M. P. Tosi; Giovanni Vignale
Motivated by the large interest in the nonequilibrium dynamics of low-dimensional quantum many-body systems, we present a fully microscopic theoretical and numerical study of the charge and spin dynamics in a one-dimensional ultracold Fermi gas following a quench. Our approach, which is based on time-dependent current-density-functional theory, is applicable well beyond the linear-response regime and produces both spin-charge separation and spin-drag-induced broadening of the spin packets.
Physical Review B | 2012
Jing-Jing Wang; Wei Li; Shu Chen; Gao Xianlong; Massimo Rontani; Marco Polini
Chemical vapor deposition (CVD) provides a synthesis route for large-area and high-quality graphene films. However, layer-controlled synthesis remains a great challenge on polycrystalline metallic films. Here, a facile and viable synthesis of layer-controlled and high-quality graphene films on wafer-scale Ni surface by the sequentially separated steps of gas carburization, hydrogen exposure, and segregation is developed. The layer numbers of graphene films with large domain sizes are controlled precisely at ambient pressure by modulating the simplified CVD process conditions and hydrogen exposure. The hydrogen exposure assisted with a Ni catalyst plays a critical role in promoting the preferential segregation through removing the carbon layers on the Ni surface and reducing carbon content in the Ni. Excellent electrical and transparent conductive performance, with a room-temperature mobility of approximate to 3000 cm2 V-1 s-1 and a sheet resistance as low as approximate to 100 O per square at approximate to 90% transmittance, of the twisted few-layer grapheme films grown on the Ni catalyst is demonstrated.
Physical Review B | 2010
Ji-Hong Hu; Jing-Jing Wang; Gao Xianlong; Masahiko Okumura; Ryo Igarashi; Susumu Yamada; Masahiko Machida
We revisit the one-dimensional attractive Hubbard model by using the Bethe-ansatz-based density-functional theory and density-matrix renormalization method. The ground-state properties of this model are discussed in details for different fillings and different confining conditions in weak-to-intermediate coupling regime. We investigate the ground-state energy, energy gap, and pair-binding energy and compare them with those calculated from the canonical Bardeen-Cooper-Schrieffer approximation. We find that the Bethe-ansatz-based density-functional theory is computationally easy and yields an accurate description of the ground-state properties for weak-to-intermediate interaction strength, different fillings, and confinements. In order to characterize the quantum phase transition in the presence of a harmonic confinement, we calculate the thermodynamic stiffness, the density-functional fidelity, and fidelity susceptibility, respectively. It is shown that with the increase in the number of particles or attractive interaction strength, the system can be driven from the Luther-Emery-type phase to the composite phase of Luther-Emery-type in the wings and insulatinglike in the center.
Physical Review B | 2010
Gao Xianlong
We calculate the nonequilibrium dynamic evolution of a one-dimensional system of two-component fermionic atoms after a strong local quench by using a time-dependent spin-density-functional theory. The interaction quench is also considered to see its influence on the spin-charge separation. It is shown that the charge velocity is larger than the spin velocity for the system of on-site repulsive interaction (Luttinger liquid), and vise versa for the system of on-site attractive interaction (Luther-Emery liquid). We find that both the interaction quench and polarization suppress the spin-charge separation.
Journal of Physics B | 2012
Gao Xianlong
We numerically investigate a one-dimensional Anderson–Hubbard model under harmonic confinement. The effects of disorder on the ground-state properties are studied for Gaussian-correlated disorder and random impurities upon changing the amplitude of the disorder strength, the correlation length or the number of impurities. For a large disorder correlation length, both the band- and Mott-insulating phases re-enter naturally as a result of a smooth long-range correlated disorder. For the randomly distributed impurities in a system of composite Mott- and band-insulating phases, we find that the band-insulating region is rapidly destroyed while the Mott region is more robust against the increase of impurities. The fluid regions are less affected in this case.
Journal of Physics B | 2004
S. N. Artemenko; Gao Xianlong; W. Wonneberger
Using an asymptotic phase representation of the particle density operator in the one-dimensional harmonic trap, the part which describes the Friedel oscillations is extracted. The expectation value with respect to the interacting ground state requires the calculation of the mean square average of a properly defined phase operator. This calculation is performed analytically for the Tomonaga?Luttinger model with harmonic confinement. It is found that the envelope of the Friedel oscillations at zero temperature decays with the boundary exponent ? = (K+1)/2 away from the classical boundaries. This value differs from that known for open boundary conditions or strong pinning impurities. The soft boundary in the present case thus modifies the decay of Friedel oscillations. The case of two components is also discussed.
Journal of Physics B | 2011
Jing-Jing Wang; Gao Xianlong
We present a numerical study on one-dimensional attractive Fermi gases with spin polarization in the presence of the harmonic confinement and the speckle disorder by making use of the local-density approximation based on the exact Bethe-ansatz solution. The effects of the disorder are investigated on the ground-state properties. For a clean system without trapping, the ground state is a partially polarized Fulde?Ferrell?Larkin?Ovchinnikov (FFLO) state, a full paired Bardeen?Cooper?Schrieffer (BCS) state or a fully polarized normal state. For a clean system in the presence of trapping, a two-shell structure exists with a polarized superfluid core surrounded by wings composed of either an unpolarized superfluid (FFLO-BCS) or a fully polarized normal (FFLO-N) gas. Between these two different phases, there exists a critical polarization where a pure FFLO state happens. In the presence of speckle disorder with fixed polarization, the system can be changed from FFLO-BCS to FFLO-N upon increasing the disorder amplitude, irrelevant to the attractive or repulsive nature of the speckle disorder. Given the dimensionless interaction strength ?0 and the disorder amplitude A, there is a critical polarization Pc below which the system is in a FFLO-BCS phase and above which it is in a FFLO-N phase.
Physical Review B | 2008
Gao Xianlong
Using the Bethe-ansatz density-functional theory, we study a one-dimensional Hubbard model of confined attractively interacting fermions in the presence of a uniformly distributed disorder. The strongly correlated Luther-Emery nature of the attractive one-dimensional Hubbard model is fully taken into account as the reference system in the density-functional theory. The effects of the disorder are investigated on the atomic density waves in the weak-to-intermediate attractive interaction and on the spin-singlet dimers of doubly occupied sites in the strongly attractive regime. It is found that atomic density waves are sensitive to the disorder and the spin-singlet dimers of doubly occupied sites are quite unstable against the disorder. We also show that a very weak disorder could smear the singularities in the stiffness, thus, suppresses the spin-singlet pairs.
Journal of Physics B | 2004
Gao Xianlong; W. Wonneberger
A phase operator formulation for a recent model of interacting one-dimensional fermions in a harmonic trap is developed. The resulting theory is similar to the corresponding approach for the Luttinger model with open boundary conditions (OBC). However, in place of the spatial coordinate z, a dimensionless variable u defined on the unit circle appears as argument of the phase fields and u is nonlinearly related to z. Furthermore, form factors appear which reflect the harmonic trap geometry. The theory is applied to calculate one-particle correlation functions. In a properly defined thermodynamic limit, bulk and boundary critical exponents are calculated for the static two-point correlation function and the dynamic local correlation function. The local spectral density is also considered. The critical exponents found are in agreement with those known for OBC with the exception of the boundary scaling exponent Δ⊥.