Squeezing of primordial gravitational waves as quantum discord

Akira Matsumura, Yasusada Nambu

Research output: Contribution to journalArticlepeer-review

4 Citations (Scopus)


We investigate the squeezing of primordial gravitational waves (PGWs) in terms of quantum discord. We construct a classical state of PGWs without quantum discord and compare it with the Bunch–Davies vacuum. Then it is shown that the oscillatory behavior of the angular-power spectrum of the cosmic microwave background (CMB) fluctuations induced by PGWs can be the signature of the quantum discord of PGWs. In addition, we discuss the effect of quantum decoherence on the entanglement and the quantum discord of PGWs for super-horizon modes. For the state of PGWs with decoherence effect, we examine the decoherence condition and the correlation condition introduced by C. Kiefer et al. (Class. Quantum Grav. 24 (2007) 1699). We show that the decoherence condition is not sufficient for the separability of PGWs and the correlation condition implies that the PGWs in the matter-dominated era have quantum discord.

Original languageEnglish
Article number33
Issue number2
Publication statusPublished - 2020
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)


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