The Relativity Principle at the Foundation of Quantum Mechanics

Abstract

Quantum information theorists have created axiomatic reconstructions of quantum mechanics (QM) that are very successful at identifying precisely what distinguishes quantum probability theory from classical and more general probability theories in terms of information-theoretic principles.Herein, we show how two such principles, i.e., "Existence of an Information Unit" and "Continuous Reversibility," map to the relativity principle as it pertains to the invariant measurement of Planck's constant h for Stern-Gerlach (SG) spin measurements in spacetime in exact analogy to the relativity principle as it pertains to the invariant measurement of the speed of light c for special relativity (SR). Essentially, quantum information theorists have extended Einstein's use of the relativity principle from the boost invariance of measurements of c to include the SO(3) invariance of measurements of h between different reference frames of mutually complementary spin measurements via the principle of "Information Invariance & Continuity." Consequently, the "average-only" conservation represented by the Bell states that is responsible for the Tsirelson bound and the exclusion of the no-signalling, "superquantum" Popescu-Rohrlich joint probabilities is understood to result from conservation per Information Invariance & Continuity between different reference frames of mutually complementary measurements, and this maps to conservation per the relativity principle in spacetime. Thus, the axiomatic reconstructions of QM have succeeded in producing a principle account of QM that is every bit as robust as the postulates of SR, revealing a still broader role for the relativity principle in the foundations of physics.