Stochastic Inflation as an Open Quantum System
Abstract
We reinterpret Starobinsky's stochastic inflation as an open quantum system, where short-wavelength modes act as the environment for long-wavelength modes. Using the Schwinger-Keldysh formalism, we systematically trace out the environment and derive an effective theory for the reduced density matrix, including deviations from exact de Sitter space. The resulting master equation is a Lindblad equation, which reduces to a Fokker-Planck equation for the diagonal elements up to higher orders in the slow-roll expansion, while also yielding a more complete equation in phase space. Finally, we extend the formalism to global de Sitter space, for which the associated Fokker-Planck equation lacks equilibrium solutions until the late-time regime aH≫1.
Fields of Study & Subjects
Cosmology and Gravitation Theories
Noncommutative and Quantum Gravity Theories
Stochastic processes and financial applications
Publication details
- Journal / source
- Physical Review Letters
- Publisher
- American Physical Society (APS)
- Volume
- 136
- Issue
- 7
- Pages
- 071501–071501
- Publication date
- 26 January 2026
- Language
- EN