Hanbury Brown-Twiss interferometry and second-order correlations of inflaton quanta

TL;DR

This paper applies quantum optical coherence theory to analyze the statistical properties of relic inflaton quanta, revealing their super-Poissonian and super-chaotic nature through second-order correlations, with implications for cosmological observations.

Contribution

It introduces a novel application of Hanbury Brown-Twiss interferometry to cosmological inflaton quanta, linking quantum statistical properties to observable intensity correlations.

Findings

Inflaton quanta exhibit super-Poissonian and super-chaotic statistics.

Second-order correlations can be used to distinguish quantum from classical origins.

Finite volume effects influence the persistence of quantum correlations.

Abstract

The quantum theory of optical coherence is applied to the scrutiny of the statistical properties of the relic inflaton quanta. After adapting the description of the quantized scalar and tensor modes of the geometry to the analysis of intensity correlations, the normalized degrees of first-order and second-order coherence are computed in the concordance paradigm and are shown to encode faithfully the statistical properties of the initial quantum state. The strongly bunched curvature phonons are not only super-Poissonian but also super-chaotic. Testable inequalities are derived in the limit of large angular scales and can be physically interpreted in the light of the tenets of Hanbury Brown-Twiss interferometry. The quantum mechanical results are compared and contrasted with different situations including the one where intensity correlations are the result of a classical stochastic process. The survival of second-order correlations (not necessarily related to the purity of the initial quantum state) is addressed by defining a generalized ensemble where super-Poissonian statistics is an intrinsic property of the density matrix and turns out to be associated with finite volume effects which are expected to vanish in the thermodynamic limit.