Entanglement masquerading in the CMB

Abstract

The simplest single-field inflation models capture all the relevant contributions to the patterns in the Cosmic Microwave Background (CMB) observed today. A key assumption in these models is that the quantum inflationary fluctuations that source such patterns are generated by a particular quantum state -- the Bunch-Davies (BD) state. While this is a well-motivated choice from a theoretical perspective, the question arises of whether current data can rule out other, also well motivated, choices of states. In particular, as we previously demonstrated in arXiv:2104.13410 [hep-th], entanglement is naturally and inevitably dynamically generated during inflation given the presence of a "rolling" spectator scalar field -- and the resulting entangled state will yield a primordial power spectrum with potentially measurable deviations compared to the canonical BD result. For this work we developed a perturbative framework to allow a systematic exploration of constraints on (or detection of) entangled states with Planck CMB data using Monte Carlo techniques. We have found that most entangled states accessible with our framework are consistent with the data. One would have to expand the framework to allow a greater variety of entangled states in order to saturate the Planck constraints and more systematically explore any preferences the data may have among the different possibilities.

37 pages, 12 figures, 3 appendices. V2: Final version accepted for publication in JCAP. Changes: References added and minor clarifications to the presentation. Our results and conclusions are unchanged

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Cited by in corpus (4)

• The Open Effective Field Theory of Inflation
• Circumventing Cosmic Variance via Remote Quadrupole Measurements
• A Search for Classical Subsystems in Quantum Worlds
• Entangled states as a probe of early universe history: a Higgs case study