All matter is built from constituents that obey quantum mechanical laws, ranging from quarks and nucleons, to electrons, to atoms and molecules. In many cases quantum mechanics is also of crucial importance to understand not only the constituents themselves, but also their interactions and their large-scale collective behavior – such systems are instances of macroscopic quantum matter. Examples include electrons in solids, quark matter (e.g. the quark- gluon plasma), nuclear matter (e.g. neutron stars), and ultra-cold gases of atoms and molecules. The study of these systems encompasses many of the most exciting and challenging problems in physics, and is a focus of effort in a diverse collection of sub-disciplines, including atomic, molecular and optical physics, condensed matter physics, nuclear physics, high-energy physics, and quantum information science.
Quantum matter is complex, but also possesses a high degree of underlying simplicity. To expose this underlying simplicity and connect it to experimentally measurable properties requires a variety of tools and concepts at the cutting edge of theoretical physics, and theory therefore plays a leading role in the study of quantum matter. The quantum matter systems studied in each sub-discipline differ, often dramatically so, but from a theorist’s point of view there are equally dramatic similarities between seemingly disparate systems. On the other hand, each sub-discipline has its own language and its own set of tools; this is an opportunity, but one that can only be exploited with a concerted joint effort.
There is thus tremendous potential to develop the theory of quantum matter as an inter-disciplinary activity, cutting across the traditional sub-disciplines of physics. This is the principal goal of CTQM.
CTQM includes those sub-fields of theoretical physics that are substantially concerned with macroscopic quantum matter. This includes: