arXiv subjects

X. W. Guan

Publications and source records attributed to X. W. Guan.

24 records · Page 2Linked to original sources

arXiv2005

Exact results for the 1D interacting mixed Bose-Fermi gas

The exact solution of the 1D interacting mixed Bose-Fermi gas is used to calculate ground-state properties both for finite systems and in the thermodynamic limit. The quasimomentum distribution, ground-state energy and generalized velocities are obtained as functions of the interaction strength both for polarized and non-polarized fermions. We do not observe any demixing instability of the system for repulsive interactions.

cond-mat.stat-mech↗

arXiv2005

Evidence for the super Tonks-Girardeau gas

We provide evidence in support of a recent proposal by Astrakharchik at al. for the existence of a super Tonks-Girardeau gas-like state in the attractive interaction regime of quasi-one-dimensional Bose gases. We show that the super Tonks-Giradeau gas-like state corresponds to a highly-excited Bethe state in the integrable interacting Bose gas for which the bosons acquire hard-core behaviour. The gas-like state properties vary smoothly throughout a wide range from strong repulsion to strong attraction. There is an additional stable gas-like phase in this regime in which the bosons form two-body bound states behaving like hard-core bosons.

cond-mat.stat-mech↗

arXiv2005

The 1D interacting Bose gas in a hard wall box

We consider the integrable one-dimensional delta-function interacting Bose gas in a hard wall box which is exactly solved via the coordinate Bethe Ansatz. The ground state energy, including the surface energy, is derived from the Lieb-Liniger type integral equations. The leading and correction terms are obtained in the weak coupling and strong coupling regimes from both the discrete Bethe equations and the integral equations. This allows the investigation of both finite-size and boundary effects in the integrable model. We also study the Luttinger liquid behaviour by calculating Luttinger parameters and correlations. The hard wall boundary conditions are seen to have a strong effect on the ground state energy and phase correlations in the weak coupling regime. Enhancement of the local two-body correlations is shown by application of the Hellmann-Feynman theorem.

cond-mat.stat-mech↗

arXiv2004

Ground state of one-dimensional bosons with delta interaction: link to the BCS model

The Bethe roots describing the ground state energy of the integrable 1D model of interacting bosons with weakly repulsive two-body delta interactions are seen to satisfy the set of Richardson equations appearing in the strong coupling limit of an integrable BCS pairing model. The BCS model describes boson-boson interactions with zero centre of mass momentum of pairs. It follows that the Bethe roots of the weakly interacting boson model are given by the zeros of Laguerre polynomials. The ground state energy and the lowest excitation are obtained explicitly via the Bethe roots. A direct link has thus been established, in the context of integrable 1D models, between bosons interacting via weakly repulsive two-body delta-interactions and strongly interacting Cooper pairs of bosons.

cond-mat.stat-mech↗

arXiv2000

Integrability of the $D_n^2$ vertex models with open boundary

We investigate various aspects of the integrability of the vertex models associated to the $D_n^2$ affine Lie algebra with open boundaries. We first study the solutions of the corresponding reflection equation compatible with the minimal symmetry of this system. We find three classes of general solutions, one diagonal solution and two non-diagonal families with a free parameter. Next we perform the Bethe ansatz analysis for some of the associated open $D_2^2$ spin chains and we identify the boundary having quantum group invariance. We also discuss a new $D_2^2$ $R$-matrix.

nlin.SI↗

arXiv1999

Integrable supersymmetric correlated electron chain with open boundaries

We construct an extended Hubbard model with open boundaries from a $R$-matrix based on the $U_q[Osp(2|2)]$ superalgebra. We study the reflection equation and find two classes of diagonal solutions. The corresponding one-dimensional open Hamiltonians are diagonalized by means of the Bethe ansatz approach.

solv-int↗