Thomas Colas
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Lectures on Open Effective Field Theories Open
Effective field theories offer a powerful method to unify diverse models under a small set of control parameters, allowing systematic expansions around well-established theories. These techniques, developed in particle physics, were design…
Quantum estimation of cosmological parameters Open
Understanding how well future cosmological experiments can reconstruct the mechanism that generated primordial inhomogeneities is key to assessing the extent to which cosmology can inform fundamental physics. In this work, we apply a quant…
An Open Effective Field Theory for light in a medium Open
A bstract 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 develo…
Does decoherence violate decoupling? Open
A bstract Recent calculations in both flat and de Sitter spacetimes have highlighted a tension between the decoupling of high-energy physics from low-energy degrees of freedom and the expectation that quantum systems decohere due to intera…
An Open Effective Field Theory for light in a medium Open
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 per…
Does decoherence violate decoupling? Open
Recent calculations in both flat and de Sitter spacetimes have highlighted a tension between the decoupling of high-energy physics from low-energy degrees of freedom and the expectation that quantum systems decohere due to interactions wit…
The open effective field theory of inflation Open
A bstract In our quest to understand the generation of cosmological perturbations, we face two serious obstacles: we do not have direct information about the environment experienced by primordial perturbations during inflation, and our obs…
In-in formalism for the entropy of quantum fields in curved spacetimes Open
We show how to compute the purity and entanglement entropy for quantum fields in a systematic perturbative expansion. To that end, we generalize the in-in formalism to non-unitary dynamics (i.e. accounting for the presence of an environmen…
Cosmic purity lost: perturbative and resummed late-time inflationary decoherence Open
We compute the rate with which unobserved fields decohere other fields to which they couple, both in flat space and in de Sitter space, for spectator scalar fields prepared in their standard adiabatic vacuum. The process is very efficient …
Open Effective Field Theories for cosmology Open
When energy is not conserved, imprints of new physics on observable cosmology might not follow the rules of local effective actions. By capturing dissipative and diffusive effects, open effective field theories account for the possibly non…
Decoherence out of fire: purity loss in expanding and contracting universes Open
We investigate quantum decoherence in a class of models which interpolates between expanding (inflation) and contracting (ekpyrosis) scenarios. For the cases which result in a scale-invariant power spectrum, we find that ekpyrotic universe…
The Open Effective Field Theory of Inflation Open
In our quest to understand the generation of cosmological perturbations, we face two serious obstacles: we do not have direct information about the environment experienced by primordial perturbations during inflation, and our observables a…
Cosmic Purity Lost: Perturbative and Resummed Late-Time Inflationary Decoherence Open
We compute the rate with which unobserved fields decohere other fields to which they couple, both in flat space and in de Sitter space, for spectator scalar fields prepared in their standard adiabatic vacuum. The process is very efficient …
Decoherence out of fire: Purity loss in expanding and contracting universes Open
We investigate quantum decoherence in a class of models which interpolates between expanding (inflation) and contracting (ekpyrosis) scenarios. For the cases which result in a scale-invariant power spectrum, we find that ekpyrotic universe…
Systèmes quantiques ouverts pour la cosmologie primordiale : dissipation, décohérence et effets séculiers des inhomogénéités cosmologiques Open
This thesis develops the implementation of Open Effective Field Theories in primordial cosmology. Offering a unique window onto unknown physics, primordial cosmology faces uncertainties regarding extensions to the minimal framework of sing…
Quantum recoherence in the early universe Open
Despite being created through a fundamentally quantum-mechanical process, cosmological structures have not yet revealed any sign of genuine quantum correlations. Among the obstructions to the direct detection of quantum signatures in cosmo…
Quantum recoherence in the early universe Open
Despite being created through a fundamentally quantum-mechanical process, cosmological structures have not yet revealed any sign of genuine quantum correlations. Among the obstructions to the direct detection of quantum signatures in cosmo…
Benchmarking the cosmological master equations Open
Master equations are commonly employed in cosmology to model the effect of additional degrees of freedom, treated as an “environment”, onto a given “system”. However, they rely on assumptions that are not necessarily satisfied in cosmology…
Benchmarking the cosmological master equations Open
Master equations are commonly employed in cosmology to model the effect of additional degrees of freedom, treated as an "environment", onto a given "system". However, they rely on assumptions that are not necessarily satisfied in cosmology…
Efficient cosmological analysis of the SDSS/BOSS data from the Effective Field Theory of Large-Scale Structure Open
The precision of the cosmological data allows us to accurately approximate the predictions for cosmological observables by Taylor expanding up to a low order the dependence on the cosmological parameters around a reference cosmology. By ap…