Einselection, Equilibrium and Cosmology

Abstract

Our observed Universe has a very strong arrow of time rooted in its low entropy starting point. This low entropy start can be related to various "tuning puzzles" about the early state of the Universe. Here we explore the relationship between the arrow of time and the emergence of classical from quantum in the hopes of ultimately gaining insights into cosmological initial conditions. Our focus is on einselection, the process whereby interactions with an environment select preferred states for a quantum system. This process plays an essential role in the emergence of classical from quantum. Studies of einselection have so far been limited to cases that exhibit an arrow of time. Here we study the ability of equilibrium systems to exhibit einselection -- and investigate whether detailed balance prevents this -- motivated by the question of whether classicality requires an arrow of time. We present calculations in the adapted Caldeira-Leggett model which demonstrate that einselection can indeed take place in equilibrium systems, and show how this phenomenon is tied to histories which express an arrow of time, despite the global equilibrium. We discuss some interesting implications of our results for cosmology and cosmological initial conditions. We are intrigued and a bit surprised by the role the consistent histories formalism has ended up playing in our analysis.

19 pages, 14 figures, 2 appendices. V2: Final version accepted for publication in PRD. A number of edits have been made to improve the clarity of our discussion. Our results and conclusions are unchanged

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• The Measure Problem in Cosmology
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• Supersmoothing through Slow Contraction
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• Quantum Physics and Human Language
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Cited by in corpus (11)

• Quantum Theory of the Classical: Einselection, Envariance, Quantum Darwinism and Extantons
• Ergotropy and capacity optimization in Heisenberg spin-chain quantum batteries
• Classicality with(out) decoherence: Concepts, relation to Markovianity, and a random matrix theory approach
• First Principles Numerical Demonstration of Emergent Decoherent Histories
• Adapted Caldeira-Leggett Model
• The Decoherent Arrow of Time and the Entanglement Past Hypothesis
• Equilibration and "Thermalization'' in the Adapted Caldeira-Leggett model
• Decoherence of Histories: Chaotic Versus Integrable Systems
• Non-Markovianity in the Adapted Caldeira-Leggett model
• Copycat process in the early stages of einselection
• A Search for Classical Subsystems in Quantum Worlds