An Open Effective Field Theory for light in a medium

Abstract

In many scenarios of interest, a quantum system interacts with an unknown environment, necessitating the use of open quantum system methods to capture dissipative effects and environmental noise. With the long-term goal of developing a perturbative theory for open quantum gravity, we take an important step by studying Abelian gauge theories within the Schwinger-Keldysh formalism. We begin with a pedagogical review of general results for open free theories, setting the stage for our primary focus: constructing the most general open effective field theory for electromagnetism in a medium. We assume locality in time and space, but allow for an arbitrary finite number of derivatives. Crucially, we demonstrate that the two copies of the gauge group associated with the two branches of the Schwinger-Keldysh contour are not broken but are instead deformed by dissipative effects. We provide a thorough discussion of gauge fixing, define covariant gauges, and calculate the photon propagators, proving that they yield gauge-invariant results. A notable result is the discovery that gauge invariance is accompanied by non-trivial constraints on noise fluctuations. We derive these constraints through three independent methods, highlighting their fundamental significance for the consistent formulation of open quantum gauge theories.

50 pages in total, 1 figure; matches published version in JHEP

References in corpus (70)

• Keldysh Field Theory for Driven Open Quantum Systems
• The Effective Field Theory of Dark Energy
• Keldysh technique and non-linear sigma-model: basic principles and applications
• Massive Islands
• Inconsistency of Islands in Theories with Long-Range Gravity
• Entanglement entropy in de Sitter space
• Decoherence during Inflation: the generation of classical inhomogeneities
• A Master Equation for Gravitational Decoherence: Probing the Textures of Spacetime
• Open EFTs, IR Effects and Late-Time Resummations: Systematic Corrections in Stochastic Inflation
• Schwinger-Keldysh formalism I: BRST symmetries and superspace
• On the Decoherence of Primordial Fluctuations During Inflation
• An effective field theory during inflation: reduced density matrix and its quantum master equation
• Quantum Decoherence During Inflation from Gravitational Nonlinearities
• Decoherence, discord and the quantum master equation for cosmological perturbations
• Entanglement Entropy of Cosmological Perturbations
• Theory of diffusive fluctuations
• An effective field theory during inflation II: stochastic dynamics and power spectrum suppression
• Open quantum systems and Schwinger-Keldysh holograms
• Observational constraints on quantum decoherence during inflation
• Minimal decoherence from inflation
• A cosmological open quantum system
• Effective Field Theory out of Equilibrium: Brownian quantum fields
• Nonlinear Langevin dynamics via holography
• Benchmarking the cosmological master equations
• Positivity bounds on effective field theories with spontaneously broken Lorentz invariance
• Killing Horizons Decohere Quantum Superpositions
• Hot Accelerated Qubits: Decoherence, Thermalization, Secular Growth and Reliable Late-time Predictions
• Open quantum dynamics induced by light scalar fields
• Open Quantum Entanglement: A study of two atomic system in static patch of de Sitter space
• The Open Effective Field Theory of Inflation
• Quantum corrections to the primordial tensor spectrum: Open EFTs & Markovian decoupling of UV modes
• Quantum recoherence in the early universe
• Universal signature of quantum entanglement across cosmological distances
• Imprint of entanglement entropy in the power spectrum of inflationary fluctuations
• Effective Lagrangian for Nambu-Goldstone modes in nonequilibrium open systems
• Thermalization in Quenched Open Quantum Cosmology
• Cosmic decoherence: primordial power spectra and non-Gaussianities
• Cosmic Purity Lost: Perturbative and Resummed Late-Time Inflationary Decoherence
• Qubits on the Horizon: Decoherence and Thermalization near Black Holes
• Effective field theory of time-translational symmetry breaking in nonequilibrium open system
• Information loss in effective field theory: entanglement and thermal entropies
• Effective master equations for two accelerated qubits
• Non-equilibrium dynamics of Axion-like particles: the quantum master equation
• Decoherence out of fire: Purity loss in expanding and contracting universes
• Quantum Hotspots: Mean Fields, Open EFTs, Nonlocality and Decoherence Near Black Holes
• Master equation for the Unruh-DeWitt detector and the universal relaxation time in de Sitter space
• Non-Markovian open quantum system approach to the early universe: I. Damping of gravitational waves by matter
• Cosmic Decoherence: Massive Fields
• On the Decoherence of Primordial Gravitons
• Semiclassical Approximation meets Keldysh-Schwinger diagrammatic technique: Scalar ${\phi }^4$
• In-in formalism for the entropy of quantum fields in curved spacetimes
• Dilaton-induced open quantum dynamics
• A new method for directly computing reduced density matrices
• The Schwinger-Keldysh Coset Construction
• Local Description of Decoherence of Quantum Superpositions by Black Holes and Other Bodies
• Qubit Heating Near a Hotspot
• Quantum thermodynamics of de Sitter space
• Open Quantum System Approach to the Gravitational Decoherence of Spin-1/2 Particles
• Relating the curvature of De Sitter Universe to Open Quantum Lamb Shift Spectroscopy
• On the origin of entropy of gravitationally produced dark matter: the entanglement entropy
• Photon Chiral Memory Effect Stored on Celestial Sphere
• Decoherence of Cosmological Perturbations from Boundary Terms and the Non-Classicality of Gravity
• Influence functionals, decoherence and conformally coupled scalars
• Classifying the non-time-local and entangling dynamics of an open qubit system
• Density matrix formalism for interacting quantum fields
• Cosmological Bell Tests with Decoherence Effects
• Graviton physics: Quantum field theory of gravitons, graviton noise and gravitational decoherence -- a concise tutorial
• Gravity, Horizons and Open EFTs
• The effect of quantum decoherence on inflationary gravitational waves
• Frequency shifts induced by light scalar fields

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