This chapter is the introduction to this book, its motivation and its design and how it can be applied to the design of undergraduate and graduate courses on quantum optics and superconducting quantum circuits.

At the macroscale, thermodynamics rules the balances of energy and entropy. In nonisolated systems, the entropy changes due to the contributions from the internal entropy production, which is always nonnegative according to the second law, and the exchange of entropy with the environment. The entropy production is equal to zero at equilibrium and positive out of equilibrium. Thermodynamics can be formulated either locally for continuous media or globally for systems in contact with several reservoirs. Accordingly, the entropy production is expressed in terms of either the local or the global affinities and currents, the affinities being the thermodynamic forces driving the system away from equilibrium. Depending on the boundary and initial conditions, the system can undergo relaxation towards equilibrium or nonequilibrium stationary or time-dependent macrostates. As examples, thermodynamics is applied to diffusion, electric circuits, reaction networks, and engines.

The historical backdrop for the role of microscopy in the development of human knowledge is reviewed. Atomic-scale investigations are a logical step in a natural progression of increasingly more powerful microscopies. A brief outline of the concept of atomic-scale analytical tomography (ASAT) is given, and its implications for science and technology are anticipated. The intersection of ASAT with advanced computational materials engineering is explored. The chapter concludes with a look toward a future where ASAT will become common.

This chapter introduces the basic theoretical tools for handling many-body quantum systems. Starting from second quantized operators, we discuss how it is possible to describe the composite wavefunction of multi-particle systems, and discuss representations in various bases. The algebra of Fock states is described for single and multi-mode systems, and how they relate to the eigenstates of the Schrodinger equation. Finally, we describe how interactions between particles can be introduced in a general way, and then describe the most common type of interaction in cold atom systems, the s-wave interaction

The fundamental description of the absorption of light by a gas through the Beer-Lambert law is introduced with the definitions given of the important parameters, such as line-strength, absorption cross-section and absorption coefficient. Broadening of gas absorption lines from Doppler effects and molecular collisions is explained in detail and the consequent absorption line-shape functions are presented in the form of Gaussian, Lorentzian or Voigt profiles. The extraction of information on the gas concentration, pressure or temperature from a measured line-shape is discussed, along with the practical issues and limitations. The origin and nature of the absorption lines arising from the excitation of rotational and vibrational states of gas molecules is reviewed with a particular interest in the overtone lines in the near-IR region. Examples of near-IR absorption lines from the HITRAN database for carbon monoxide, carbon dioxide, acetylene, methane, water, ammonia and hydrogen sulfide are presented so that the optical attenuation may be calculated in the design of a practical gas sensor system.