arXiv subjects

Jaime Calderón-Figueroa

Publications and source records attributed to Jaime Calderón-Figueroa.

11 recordsLinked to original sources

arXiv2026

Heterotic Warm Inflation

We propose a two-field model of warm inflation motivated by a heterotic string construction, involving an axion and a dilaton-like scalar field with non-trivial kinetic mixing. Gauge-field interactions generate dissipation and thermal corrections affecting both fields. A systematic numerical analysis reveals a range of dynamical regimes, including effectively single-field and multi-field behavior. We find that warm inflation is typically realized along the axion direction, while thermal corrections tend to hinder sustained dilaton-driven inflation over most of the parameter space. Although configurations exist in which the dilaton becomes dynamically relevant, particularly near the end of inflation, the majority of viable solutions are effectively single-field and axion-dominated. These results point to a dynamical mechanism in heterotic-inspired models that naturally favors axion-driven warm inflation while limiting the role of the dilaton.

hep-th↗

arXiv2025

Stochastic instantons and the tail of the inflationary density perturbation

In the "stochastic $δN$ formalism", the statistics of the inflationary density perturbation are obtained from the first passage distribution of a stochastic process. We develop a general framework in which to evaluate the rare tail of this distribution, based on an instanton approximation to a path integral representation for the transition probability. We relate our formalism to the Schwinger-Keldysh path integral, by integrating out short wavelength degrees of freedom to produce an influence functional. This provides a principled way to extend the calculation beyond the slow-roll limit, and to models with multiple fields. We argue that our framework has a number of advantages in comparison with existing methods. In particular, it reliably captures the tail behaviour in cases where existing techniques do not apply, including cases where the noise amplitude has strong time dependence. We demonstrate the method by computing the tail probability in a number of scenarios, including a beyond-slow-roll analysis of a linear potential, ultra-slow-roll, and constant-roll inflation. We find close agreement with results already reported in the literature. Finally, we discuss a scenario with exponentially decaying noise amplitude. This is a model for the stochastic evolution of a fixed comoving volume of spacetime on superhorizon scales. In this case we show that the tail reverts to a Gaussian weight.

astro-ph.CO↗

arXiv2025

Is the CMB revealing signs of pre-inflationary physics?

Given the latest observational constraints coming from the joint analyses of the Atacama Cosmology Telescope, the Planck Satellite and other missions, we point out the possibility of reconciling fundamental particle-physics models of inflation with data by considering non-Bunch-Davies initial conditions for primordial density perturbations.

astro-ph.CO↗

arXiv2024

The special case of slow-roll attractors in de Sitter: Non-Markovian noise and evolution of entanglement entropy

We analyse the evolution of the reduced density matrix of inflationary perturbations, coupled to a heavy entropic field via the leading-order term within the Effective Field Theory of Inflation, for two nearly de Sitter backgrounds. We perform a full quantum treatment of the open system and derive a Fokker-Planck equation to describe decoherence and the entanglement structure of the adiabatic perturbations. We find that exotic phenomena, such as recoherence and transient negative growth of entanglement entropy, appearing for the attractor solution, are absent for the non-attractor background. We comment on the relationship of these to the non-Markovian nature of the system. Finally, we generalise to the case where a few e-folds of ultra-slow roll evolution are sandwiched between phases of slow-roll inflation to find its (memory) effects on the curvature perturbation.

hep-th↗

arXiv2024

Time-convolutionless cosmological master equations: Late-time resummations and decoherence for non-local kernels

We revisit a simple toy model of two scalar fields in de Sitter space, playing the roles of "system" and "environment" degrees of freedom, which interact with each other. We show that there are secular divergences in physically relevant observables which arise solely from the non-Markovian part of the memory kernel, contrary to popular belief that secular growth typically comes from local terms in evolution equations. Nevertheless, we show that these terms can still be non-perturbatively resummed, using the time-convolutionless master equation formalism, which improves upon previous approximations. At the same time, there are other physical quantities in the same model that are dominated by local terms in the memory kernel. Therefore, we conclude that, for cosmological backgrounds, either the dissipation or the noise kernel can end up being dominated by non-local terms depending on the nature of the system-environment coupling.

hep-th↗

arXiv2023

Astrophysically sourced quantum coherent photonic signals

Stimulated emission is shown to be robust in stars. Through Bose enhancement this produces quantum states of aligned, monochromatic photons similar to a laser. The probability of creating such states is computed. We show that from the solar corona such quantum states would propagate outside of the solar region and through the Solar System without decoherence. For a $1 {\rm m}^2$ detector at the distance of the Earth from the Sun we estimate rates of such quantum states in the few per second thus potentially detectable. The same process should lead to such quantum states also arriving from stars at interstellar distances.

hep-ph↗

arXiv2023

Momentum-space entanglement entropy in de Sitter

We study the momentum-space entanglement between the sub- and super-Hubble modes of a spectator scalar field, with a cubic $λϕ^3$ interaction, in de Sitter space. Momentum-space entanglement has some universal properties for any interacting quantum field theory, and we examine them for this specific curved background using the Hubble scale as a natural delimiter to define UV/IR separation. We show that there are several new subtleties when generalising flat space results due to having a time-dependent interaction term and a non-trivial vacuum state. Our main finding is that the momentum-space entanglement entropy in de Sitter space grows very rapidly, supporting previous similar results for cosmological perturbations [1], which leads to interesting new questions.

hep-th↗

arXiv2022

Quantum corrections to the primordial tensor spectrum: Open EFTs & Markovian decoupling of UV modes

Perturbative quantum corrections to primordial power spectra are important for testing the robustness and the regime of validity of inflation as an effective field theory. Although this has been done extensively for the density power spectrum (and, to some extent, for the tensor spectrum) using loop corrections, we do so in an open quantum system approach to the problem. Specifically, we calculate the first order corrections to the primordial gravitational wave spectrum due to (cubic) tensor interactions alone. We show that our results match expectations from standard loop corrections only in the strict Markovian limit, and therefore, establish a systematic way to relax this approximation in the future, as is generally necessary for gravitational systems.

hep-th↗

arXiv2022

Viability of quantum communication across interstellar distances

The possibility of achieving quantum communication using photons across interstellar distances is examined. For this, different factors are considered that could induce decoherence of photons, including the gravitational field of astrophysical bodies, the particle content in the interstellar medium, and the more local environment of the Solar System. The X-ray region of the spectrum is identified as the prime candidate to establish a quantum communication channel, although the optical and microwave bands could also enable communication across large distances. Finally, we discuss what could be expected from a quantum signal emitted by an extraterrestrial civilization, as well as the challenges for the receiver end of the channel to identify and interpret such signals.

quant-ph↗

arXiv2021

Universal signature of quantum entanglement across cosmological distances

Although the paradigm of inflation has been extensively studied to demonstrate how macroscopic inhomogeneities in our universe originate from quantum fluctuations, most of the established literature ignores the crucial role that entanglement between the modes of the fluctuating field plays in its observable predictions. In this paper, we import techniques from quantum information theory to reveal hitherto undiscovered predictions for inflation which, in turn, signals how quantum entanglement across cosmological scales can affect large scale structure. Our key insight is that observable long-wavelength modes must be part of an open quantum system, so that the quantum fluctuations can decohere in the presence of an environment of short-wavelength modes. By assuming the simplest model of single-field inflation, and considering the leading order interaction term from the gravitational action, we derive a universal lower bound on the observable effect of such inescapable entanglement.

hep-th↗

arXiv2021

Quantum coherence of photons at cosmological distances

We identify potential sources of decoherence for $U(1)$ gauge bosons from a cosmological standpoint. Besides interactions with different species in the cosmological medium, we also consider effects due to the expansion of the Universe, which can produce particles (especially scalars) than can potentially interact with the photon in a quantum state. We look in particular at the case of axion-like particles and their predicted decay channels in our analysis. These interactions are shown to have a negligible effect as far as decoherence goes. Interaction rates with CMB radiation or through Thomson scattering are small, so that the interstellar medium remains the biggest decoherence factor. Thus, quantum teleportation experiments with photon energies in the range $1$-$10$ keV should be feasible at cosmological distances up to the galaxy formation epoch or beyond ($z \sim 100$).

hep-ph↗