Quantum Electromagnetics

Chapter 15 derived the fundamental theory and eigenstates for the quantized radiation field and then showed how the quantum vacuum gives rise to spontaneous emission. This chapter now goes more deeply into the meaning and implications of the quantized field. The polarization of a photon can be used as a qubit and the photonic qubit is called a flying qubit. It enables transmission of information from one node to another. Spontaneous emission is shown to enable creation of an entangled state between a photonic qubit and the spin of an electron. Spontaneous emission can also degrade the performance of some device designs and in other devices it can enhance performance such as for a single photon emitter. In this we show how to engineer the vacuum to control spontaneous emission.

Introduction

This chapter provides an introduction to the book, which addresses the basic notions and fundamental elements of the modern formalism of quantum field theory and presents an introduction to quantum field theory in curved space and quantum gravity. The chapter begins with a discussion of what constitutes a quantum theory and provides some preliminary notes on the topic. It then goes on to outline the structure of the book. The general notion of a quantized field is discussed. In addition, the Klein-Gordon equation, natural units, notations and conventions are introduced.

The Solution to Graviton as Goldstone Boson

The study of Graviton as Goldstone bosons appeared in the 1960s, after Bjorken interacting idea of Electrodynamics. However, no recent advancement has been done in the field, because of very constraints as well as low-attractiveness of the theory. We do the non-metric tensor (covariant derivative of the metric tensor) case of Gravitation and eventually get SO(1,3) broken in the vacuum state of quantized field theory, then find the Graviton as Goldstone Boson. We, in final, see that Gravitons can have appearances in many modified (and extended) theories of Gravitation.

Introduction, generation and entanglement of entangled displaced even and odd squeezed states

In this paper, first, we introduce special types of entangled quantum states named “entangled displaced even and odd squeezed states” by using displaced even and odd squeezed states which are constructed via the action of displacement operator on the even and odd squeezed states, respectively. Next, we present a theoretical scheme to generate the introduced entangled states. This scheme is based on the interaction between a [Formula: see text]-type three-level atom and a two-mode quantized field in the presence of two strong classical fields. In the continuation, we consider the entanglement feature of the introduced entangled states by evaluating concurrence. Moreover, we study the influence of the displacement parameter on the entanglement degree of the introduced entangled states and compare the results. It will be observed that the concurrence of the “entangled displaced odd squeezed states” has less decrement with respect to the “entangled displaced even squeezed states” by increasing the displacement parameter.