Overview and Background

Nicolaas P. Landsman

Jacob P. Covey

Luigi A. Lugiato, Gian‐Luca Oppo

A brief overview of quantum effects in spatial structures such as nonlinear optical patterns, chains of trapped ions and atoms in optical lattices is presented. Some of the main results of the contributions to this Focus Issue are also briefly described.

Ricardo A. Broglia, G. Colò, Giovanni Onida +1 more

Rudolf Haag

No author provided

A brief review is presented on the studies of the hole motion in a two-dimensional quantum antiferromagnet. An extended introduction is given to cover the background of the problem. The quantum Bogoliubov-de Gennes formalism which treats the local distortion of the spin configuration and the quantum renormalization process on an equal footing, is outlined. The latest development on the central issue, whether a hole can freely propagate on an antiferromagnetic background, is overviewed.