arXiv subjects

Yuchuan Wen

Publications and source records attributed to Yuchuan Wen.

5 recordsLinked to original sources

arXiv2009

Quantized squeezing and even-odd asymmetry of trapped bosons

We investigate the exact nature of the superfluid-to-Mott-insulator crossover for interacting bosons on an optical lattice in a one-dimensional, harmonic trap by high-precision density-matrix renormalization-group calculations. The results reveal an intermediate regime characterized by a cascade of microscopic steps. These arise as a consequence of individual boson "squeezing" events and display an even-odd alternation dependent on the trap symmetry. We discuss the experimental observation of this behavior, which is generic in an external trapping potential.

cond-mat.quant-gas↗

arXiv2009

Cold-atoms on a two-dimensional square optical lattice with an alternating potential

The cold-atom on a two-dimensional square optical lattice is studied within the hard-core boson Hubbard model with an alternating potential. In terms of the quantum Monte Carlo method, it is shown explicitly that a supersolid phase emerges due to the presence of the alternating potential. For the weak alternating potential, the supersolid state appears for the whole range of hard-core boson densities except the half-filling case, where the system is a Mott insulator. However, for the strong alternating potential, besides the supersolid and Mott insulating states, a charge density wave phase appears.

cond-mat.str-el↗

arXiv2007

Nature of Intermediate States between Superfluid and Mott insulator for Interacting Bosons in One-dimension with a Harmonic Trapping Potential

Successive quantum transitions in an intermediate regime are shown to exist between the superfluid and Mott insulating states for interacting bosonic atoms in one dimension with a trapping potential. These transitions, which are caused by the interplay of the trapping potential with the competition between the kinetic energy and the interaction, reveal novel many-body effects as reflected by low-lying excitation behavior, unconventional long-range correlations and an even-odd alternating squeezing process of superfluid bosons into the Mott insulating state. These features, most likely being generic for all dimensions when a trapping potential is involved, are relevant for both experimental observations and physical interpretation of the Mott insulator transition.

cond-mat.str-el↗

arXiv2005

One-band Hubbard model with hopping asymmetry and the effective theory at finite U: Phase diagram and metal-insulator transition

We study the one-band Hubbard model at half filling with hopping asymmetry and its effective model at finite but large U up to the second order of tmix/U. Two variational wave functions, the resonating valence bond (RVB) wave function and antiferromagnetic (AF) RVB coexisted wave function, are studied by variational Monte Carlo method on L*L square lattices up to L=12. Based on these two wave functions, the phase diagrams for both models are presented. For the Hubbard model, we find that there is a metal-insulator transition when the hopping parameter tmix which changes the local double occupant vanishes while only a metal-insulator crossover is explored for any finite tmix. For the effective model in which the perturbation expansion is up to the second order of tmix/U, a clear metal-insulator transition can be identified for both variational wave functions and the phase diagram can be drawn accordingly. In both models, we find that the systems are dominated by AF-RVB wave function when U is large while the RVB wave function is favored when U is small.

cond-mat.str-el↗

arXiv2004

Luttinger liquid with strong spin-orbital coupling and Zeeman splitting in quantum wires

We study a one-dimensional interacting electron gas with the strong Rashba spin-orbit coupling and Zeeman splitting in a quantum well. A bosonization theory is developed for this system. The tunneling current may deviate from a simple power law which is that in an ordinary Luttinger liquid. The microscopic interacting coupling and the spin-orbital parameter may be measured by varying the external magnetic field in the tunneling experiment.

cond-mat.str-el↗