This chapter surveys some of the ways in which the Copenhagen interpretation of quantum mechanics has led to a various views of the world with spiritual and moral implications; the perspective of this chapter is that most of these views are not demanded by the actual theory and experiments of quantum mechanics.

This chapter starts with the quantization of a single mode of the electromagnetic field and introduces the photon annihilation and creation operators. The photon number states are introduced. The field quadrature operators are introduced and quantum fluctuations are discussed. Multimode fields are then discussed. Thermal fields are introduced and vacuum fluctuations and the zero-point energy are discussed. The quantum phase of a quantized single-mode field is introduced.

In this chapter, we develop the conditions to observe quantum fluctuations and quantum phenomena (entanglement, superpositions, etc.) in quantum circuits. Assuming the right conditions of temperature, we develop the quantum mechanical theory that models those fluctuations in a circuit built from nondissipative superconducting elements. We use this theory of circuit quantization to obtain the quantum Hamiltonians for microwave resonators and waveguides, for superconducting qubits of various types, and for other elements such as SQUIDs. The chapter closes with an illustration of how the same theory provides us with numerical methods to study the eigenstates, eigenenergies, and dynamics of said Hamiltonians.