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On vacuum fluctuations in quantum gravity and interferometer arm fluctuations

Zurek, Kathryn M. (2022) On vacuum fluctuations in quantum gravity and interferometer arm fluctuations. Physics Letters B, 826 . Art. No. 136910. ISSN 0370-2693. doi:10.1016/j.physletb.2022.136910.

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We propose a simple model of spacetime vacuum fluctuations motivated by AdS/CFT, where the vacuum is described by a thermal density matrix, ρ = (e^(−K))/(Tr(e^(−K)) with K the modular Hamiltonian. In AdS/CFT, both the expectation value of K and its fluctuations〈ΔK²〉have been calculated; both obey an area law identical to the Bekenstein-Hawking area law of black hole mechanics:〈K〉=〈ΔK²〉= A/(4G_N), where A is the area of an (extremal) entangling surface. It has also been shown that ΔK gravitates in AdS, and hence generates metric fluctuations. These theoretical results are intriguing, but it is not known how to precisely extend such ideas about holographic quantum gravity to ordinary flat space. We take the approach of considering whether experimental signatures in metric fluctuations could determine properties of the vacuum of quantum gravity in flat space. In particular, we propose a theoretical model motived by the AdS/CFT calculations that reproduces the most important features of modular Hamiltonian fluctuations; the model consists of a high occupation number bosonic degree of freedom. We show that if this theory couples through ordinary gravitational couplings to the mirrors in an interferometer with strain sensitivity similar to what will be available for gravitational waves, vacuum fluctuations could be observable.

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Zurek, Kathryn M.0000-0002-2629-337X
Additional Information:© 2022 The Author. Published by Elsevier B.V. This is an open access article under the CC BY license ( Funded by SCOAP3. Received 7 September 2021, Accepted 13 January 2022, Available online 19 January 2022, Version of Record 20 January 2022. I especially thank Tom Banks, Cindy Keeler, Michele Papucci and Julio Parra-Martinez for detailed comments on the draft. I thank many others for discussion and criticism, including Dan Carney, Yanbei Chen, Clifford Cheung, Patrick Draper, David B. Kaplan, Dongjun Li, Juan Maldacena, Maulik Parikh, and Erik Verlinde. The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
Group:Walter Burke Institute for Theoretical Physics
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Record Number:CaltechAUTHORS:20220104-233112647
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Official Citation:Kathryn M. Zurek, On vacuum fluctuations in quantum gravity and interferometer arm fluctuations, Physics Letters B, Volume 826, 2022, 136910, ISSN 0370-2693,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:112694
Deposited By: George Porter
Deposited On:04 Jan 2022 23:40
Last Modified:01 Jun 2022 21:02

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