Conversion of squeezed gravitons into photons during inflation

Sugumi Kanno, Jiro Soda, Kazushige Ueda

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)


It is believed that relic gravitons are squeezed during inflation. If so, quantum noise induced by them can be significantly enhanced in current interferometers. However, decoherence of the gravitons during cosmic history may change the degree of squeezing. As a first step for analyzing the decoherence of the gravitons, we assume the presence of a sizable magnetic field at the beginning of inflation and study conversion processes of the squeezed gravitons into photons during inflation in the case of minimal coupling between gravitons and photons. We solve the dynamical evolution of a coupled system of gravitons and photons perturbatively and obtain squeezing parameters for the system numerically and analytically. It turns out that the gravitons are robust against the decoherence caused by the cosmological magnetic fields. We also find that the conversion rate of gravitons into photons is at a few percent at most.

Original languageEnglish
Article number083508
JournalPhysical Review D
Issue number8
Publication statusPublished - Oct 15 2022

All Science Journal Classification (ASJC) codes

  • Nuclear and High Energy Physics


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