arXiv subjects

Adam Teixidó-Bonfill

Publications and source records attributed to Adam Teixidó-Bonfill.

7 recordsLinked to original sources

arXiv2026

Cosmological Expansion Induces Interference Between Communication and Entanglement Harvesting

We investigate the interplay between genuine entanglement harvesting and communication mediated correlations for local particle detectors in expanding cosmological spacetimes. Focusing on a conformally coupled scalar field in de Sitter spacetime, we analyze how spacetime expansion induces interference between these two sources of entanglement when the detectors are in causal contact. We compare two physically distinct detector models: detectors whose spatial profile expands with the Universe, and detectors whose proper size remains fixed despite cosmological expansion. We find that the lack of time-reversal symmetry in cosmological settings generically leads to constructive or destructive interference between communication mediated correlations and harvested field correlations, dramatically affecting the entanglement that detectors can acquire. In particular, rapid expansion can suppress entanglement entirely for expanding detectors through destructive interference, even when both communication and field correlations are individually large, whereas detectors that maintain a fixed proper size remain capable of acquiring significant entanglement. Our results show that cosmological expansion qualitatively reshapes the balance between communication and harvesting, and that the detector internal cohesion (whether it expands with the Universe or not) plays a crucial role in determining whether detectors' entanglement can survive in rapidly expanding universes.

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arXiv2025

Towards an experimental implementation of entanglement harvesting in superconducting circuits: effect of detector gap variation on entanglement harvesting

Motivated by the prospect of experimental implementations of entanglement harvesting in superconducting circuits, we propose a model of variable-gap particle detector that aims to bridge some of the gaps between Unruh-DeWitt (UDW) models and realistic implementations. Using parameters tailored to potential experimental setups, we investigate entanglement harvesting in both spacelike-separated and causally connected scenarios. Our findings reveal that while variations in the energy gap reduce the ability to harvest entanglement for spacelike-separated detectors, detectors in causal contact can still become entangled through their interaction with the field. Notably, our analysis shows that (due to the derivative coupling nature of the model) even for causally connected detectors, the entanglement primarily originates from the field's correlations. This demonstrates the potential for genuine entanglement harvesting in the lab and opens the door to near-future entanglement harvesting experiments in superconducting circuits.

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arXiv2025

Entropic partial orderings of quantum measurements

We investigate four partial orderings on the space of quantum measurements (i.e on POVMs or positive operator valued measures), describing four notions of coarse/fine-ness of measurement. These are the partial orderings induced by: (1) classical post-processing, (2) measured relative entropy, (3) observational entropy, and (4) linear relation of POVMs. The orderings form a hierarchy of implication, where e.g. post-processing relation implies all the others. We show that this hierarchy is strict for general POVMs, with examples showing that all four orderings are strictly inequivalent. Restricted to projective measurements, all are equivalent. Finally we show that observational entropy equality $S_M = S_N$ (for all $ρ$) holds if and only if $M \equiv N$ are post-processing equivalent, which shows that the first three orderings induce identical equivalence classes.

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arXiv2024

Derivative coupling enables genuine entanglement harvesting in causal communication

We show that particle detectors coupled to a massless quantum field through its derivative can genuinely harvest entanglement form the field even when they are in causal contact in flat spacetime. This is particularly relevant since the derivative coupling model captures some interesting experimentally realizable systems and since the harvested entanglement peaks at full light contact.

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arXiv2024

Interference of communication and field correlations in entanglement harvesting

We reveal that the information exchange between particle detectors and their ability to harvest correlations from a quantum field can interfere constructively and destructively. This allows for scenarios where the presence of entanglement in the quantum field is actually detrimental to the process of getting the two detectors entangled.

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arXiv2022

Data processing makes POVMs coarser and observational entropies larger

We find a criterion to compare POVM measurements and decide which ones can extract more information from physical systems, with coarser POVMs always extracting less information. This criteria generalizes the previous definition of coarser POVM, and is motivated by the idea that information cannot be gained by processing the measurement outcomes. The information that a measurement cannot extract is quantified by observational entropy or coarse-grained entropy. Adequately, coarser measurements have larger observational entropies. Moreover, the characterization and properties of coarser measurements that we provide allow to straightforwardly derive several previously known results about observational entropy.

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arXiv2020

The First Law of Quantum Field Thermodynamics

We study the notion of work fluctuations in quantum field theory, highlighting that the most common definitions used in finite-dimensional quantum systems cannot be applied to quantum field theory (QFT). Then we propose work distributions that are compatible with QFT and we show that they satisfy the first law of thermodynamics up to second moments. We also show how these distributions satisfy Crooks theorem and provide a fully non-perturbative thermodynamic analysis of spacetime localized unitary processes on a quantum field.

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