Тип публикации: статья из журнала
Год издания: 2015
Идентификатор DOI: 10.1103/PhysRevA.91.053632
Ключевые слова: Wave packets, Arbitrary superposition, Asymptotic expressions, In-laboratory experiments, Intermediate fields, Localized wave packets, Packet dispersion, Translation vector, Two-dimensional lattices, Band structure
Аннотация: We analyze the Wannier-Stark spectrum of a quantum particle in tilted two-dimensional lattices with the Bloch spectrum consisting of two subbands, which could be either separated by a finite gap or connected by the Dirac points. For rational orientations of the static field given by an arbitrary superposition of the translation vecПоказать полностьюtors, the spectrum is a ladder of energy bands. We obtain asymptotic expressions for the energy bands in the limit of large and weak static fields and study them numerically for intermediate field strength. We show that the structure of energy bands determines the rate of spreading of localized wave packets, which is the quantity measured in laboratory experiments. It is shown that wave-packet dispersion becomes a fractal function of the field orientation in the long-time regime of ballistic spreading.
Журнал: PHYSICAL REVIEW A
Выпуск журнала: Vol. 91, Is. 5
ISSN журнала: 10502947
Место издания: COLLEGE PK
Издатель: AMER PHYSICAL SOC