Propagation of phase-imprinted solitons from superfluid core to Mott-insulator shell and superfluid shell

TL;DR

This study explores phase-imprinted solitons in ultracold bosons within optical lattices, revealing a new hybrid soliton type and analyzing their dynamics across superfluid and Mott-insulator shells, with implications for excitation propagation control.

Contribution

The paper uncovers a new hybrid soliton type and maps the dynamical phase diagram of phase-imprinted solitons in trapped ultracold bosons, extending previous classifications.

Findings

Hybrid soliton type identified.

Solitons at the superfluid core cannot penetrate outer shells without additional potential.

Impedance matching concept explains excitation behavior.

Abstract

We study phase-imprinted solitons of ultracold bosons in an optical lattice with a harmonic trap, which shows the superfluid (SF) and Mott-insulator (MI) shell structures. The earlier study [Konstantin V. Krutitsky, J. Larson, and M. Lewenstein, Phys. Rev. A 82, 033618 (2010).] reported three types of phase-imprinted solitons in the Bose-Hubbard model: in-phase soliton, out-of-phase soliton, and wavelet. In this paper, we uncover the dynamical phase diagram of these phase-imprinted solitons, and find another type of the phase-imprinted soliton namely, the hybrid soliton. In the harmonically trapped system, the solitonic excitations created at the SF core cannot penetrate into the outer SF shell. This repulsion at the surface of the outer SF shell can be cured by inposing a repulsive potential at the center of the trap. These results can be interpreted as a kind of the impedance matching of excitations in BECs in terms of the effective chemical potentials or the local particle numbers in the shell, and the analogous results can be observed also in the sound wave created by the local single-shot pulse potential.