Crossover between open systems dynamical regimes

Abstract

In the past few decades rapid progress has been made in the study of open quantum systems, leading to the development of a wide variety of quantum technologies as well as experiments. All such applications of quantum physics are subject to unwanted interactions with the external environment which destroy or inhibit the quantum resources they depend on, limiting their usefulness and scalability. One of the most useful phenomena in open quantum systems is non-Markovianity, which is the revival of the initial conditions which allows one to recover quantum resources after interaction with the environment. In this dissertation we study non-Markovian effects using quantum spin chains. In particular we study the additivity properties of the Breuer-Laine-Piilo (BLP) measure of non-Markovianity and show that it is subadditive for the studied model. We also find the initial states which maximise the BLP measure for a single chain and two uncorrelated chains.