HBT Interferometry and Quantum Nature of Primordial Gravitational Waves in Ho\v{r}ava-Lifshitz Gravity

TL;DR

This paper explores the quantum characteristics of primordial gravitational waves in Hořava-Lifshitz gravity, demonstrating their generation during different cosmic eras and their detectable quantum signatures via HBT interferometry, extending beyond inflationary models.

Contribution

It shows that Hořava-Lifshitz gravity can produce scale-invariant primordial gravitational waves with quantum signatures detectable by HBT interferometry, beyond inflationary predictions.

Findings

Primordial gravitational waves can be generated during radiation and matter eras.

Quantum signatures of these waves extend beyond inflationary models.

HBT interferometry can potentially detect their non-classicality.

Abstract

Ho\v{r}ava-Lifshitz gravity (to be precise, its projectable version) is recognized as a renormalizable, unitary, and asymptotically free quantum field theory of gravity. Notably, one of its cosmological predictions is that it can produce scale-invariant primordial density fluctuations and primordial gravitational waves without relying on inflation. In this paper, we investigate the quantum nature of the primordial gravitational waves generated in Ho\v{r}ava-Lifshitz gravity. It has been suggested that, for some inflationary models, the non-classicality of primordial gravitational waves in the squeezed coherent quantum state can be detected using the Hanbury Brown - Twiss (HBT) interferometry. We show that in Ho\v{r}ava-Lifshitz gravity, scale-invariant primordial gravitational waves can be generated during both the radiation-dominated and matter-dominated eras of the Universe. Moreover, the frequency range of their quantum signatures is shown to extend beyond that of inflationary models.