An introduction to operational quantum dynamics

TL;DR

This paper reviews the history, mathematical foundations, and recent advances in quantum maps and their generalizations to non-Markovian processes, highlighting their significance in quantum physics and chemistry.

Contribution

It provides a comprehensive overview of quantum maps, their representations, and recent developments in non-Markovian quantum dynamics, connecting historical discoveries to modern research.

Findings

Quantum maps are fundamental in quantum physics and chemistry.

Recent research has extended quantum maps to non-Markovian processes.

The paper offers a tomographic perspective on quantum maps.

Abstract

In the summer of 2016, physicists gathered in Torun, Poland for the 48th annual Symposium on Mathematical Physics. This Symposium was special; it celebrated the 40th anniversary of the discovery of the Gorini-Kossakowski-Sudarshan-Lindblad master equation, which is widely used in quantum physics and quantum chemistry. This article forms part of a Special Volume of the journal Open Systems & Information Dynamics arising from that conference; and it aims to celebrate a related discovery -- also by Sudarshan -- that of Quantum Maps (which had their 55th anniversary in the same year). Nowadays, much like the master equation, quantum maps are ubiquitous in physics and chemistry. Their importance in quantum information and related fields cannot be overstated. In this manuscript, we motivate quantum maps from a tomographic perspective, and derive their well-known representations. We then dive into the murky world beyond these maps, where recent research has yielded their generalisation to non-Markovian quantum processes.