Canonical quantization and the spectral action, a nice example

TL;DR

This paper explores the canonical quantization of the spectral action on a specific finite noncommutative space, revealing a discrete spectrum for the quantum distance operator and discussing gauge invariance implications.

Contribution

It introduces a quantization scheme for the spectral action on a finite spectral triple and analyzes the resulting quantum distance operator, highlighting gauge invariance effects.

Findings

Quantum distance operator has a discrete spectrum.

Gauge invariance leads to degeneracy in the distance operator.

Proposes a physical Hilbert space for the quantum theory.

Abstract

We study the canonical quantization of the theory given by Chamseddine-Connes spectral action on a particular finite spectral triple with algebra $M_2(\Cset)\oplus\Cset$. We define a quantization of the natural distance associated with this noncommutative space and show that the quantum distance operator has a discrete spectrum. We also show that it would be the same for any other geometric quantity. Finally we propose a physical Hilbert space for the quantum theory. This spectral triple had been previously considered by Rovelli as a toy model, but with a different action which was not gauge-invariant. The results are similar in both cases, but the gauge-invariance of the spectral action manifests itself by the presence of a non-trivial degeneracy structure for our distance operator.