In many applications with quantum spin systems, control functions with a sparse and pulse-shaped structure are often required. These controls can be obtained by solving quantum optimal control problems with L1L1-penalized cost functionals. In this paper, the MATLAB package LONE is presented aimed to solving L1L1-penalized optimal control problems governed by unitary-operator quantum spin models. This package implements a new strategy that includes a globalized semi-smooth Krylov–Newton scheme and a continuation procedure. Results of numerical experiments demonstrate the ability of the LONE code in computing accurate sparse optimal control solutions.#R##N#Program summary#R##N#Program title: LONE#R##N##R##N#Catalogue identifier: AEYV_v1_0#R##N##R##N#Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEYV_v1_0.html#R##N##R##N#Program obtainable from: CPC Program Library, Queen’s University, Belfast, N. Ireland#R##N##R##N#Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html#R##N##R##N#No. of lines in distributed program, including test data, etc.: 1683#R##N##R##N#No. of bytes in distributed program, including test data, etc.: 8654#R##N##R##N#Distribution format: tar.gz#R##N##R##N#Programming language: MATLAB - (OCTAVE).#R##N##R##N#Computer: Any capable of running MATLAB or OCTAVE.#R##N##R##N#Operating system: Any capable of running MATLAB or OCTAVE.#R##N##R##N#RAM: Bytes#R##N##R##N#Classification: 4.9.#R##N##R##N#External routines: gmres MATLAB routine#R##N##R##N#Nature of problem:   A semi-smooth Newton scheme for solving quantum spin-12 sparse optimal control problems.#R##N##R##N#Solution method: Full-complex semi-smooth Newton method and continuation techniques#R##N##R##N#Running time: 60–600 sec
['Gabriele Ciaramella', 'Alfio Borzì']
A LONE code for the sparse control of quantum systems