A Matter of Principle: The Principles of Quantum Theory, Dirac's Equation, and Quantum Information

TL;DR

This paper explores how fundamental principles underpin quantum theory, highlighting Dirac's derivation of his relativistic electron equation and recent extensions in quantum information theory that derive Dirac's equation without relativity.

Contribution

It analyzes the role of fundamental principles in quantum theory and presents recent work deriving Dirac's equation solely from quantum information principles.

Findings

Dirac's equation can be derived from quantum principles without relativity.

Fundamental principles guide the development of quantum theories.

Recent quantum information principles extend the foundations of quantum physics.

Abstract

This article is concerned with the role of fundamental principles in theoretical physics, especially quantum theory. The fundamental principles of relativity will be be addressed as well in view of their role in quantum electrodynamics and quantum field theory, specifically Dirac's work, which, in particular Dirac's derivation of his relativistic equation for the electron from the principles of relativity and quantum theory, is the main focus of this article. I shall, however, also consider Heisenberg's derivation of quantum mechanics, which inspired Dirac. I argue that Heisenberg's and Dirac's work alike was guided by their adherence to and confidence in the fundamental principles of quantum theory. The final section of the article discusses the recent work by G. M. D' Ariano and his coworkers on the principles of quantum information theory, which extends quantum theory and its principles in a new direction. This extension enabled them to offer a new derivation of Dirac's equation from these principles alone, without using the principles of relativity.