Quantum Fields & Gravity

- Quantum Fields in Curved Spacetimes
Quantum field theory in curved spacetimes extends quantum field theory to non-trivial backgrounds and is viewed as a low curvature regime of a deeper quantum gravity theory. Our group explores phenomena such as particle creation in black holes (Hawking radiation) and in flat spacetime under non-trivial electromagnetic fields (Schwinger effect). Recently, we’ve focused on the production of dark matter particles in the early universe, including minimal and non-minimal gravitational couplings and non-local effects. Additionally, we address quantization ambiguities that arise in these scenarios.

-Black Holes and Semiclassical Gravity
Black holes, predicted by general relativity, have singularities behind event horizons. Semiclassical gravity, which accounts for quantum field backreaction on geometry, may regularize singularities and alter collapse outcomes. Our studies include scenarios where semiclassical effects drive rapid trapped region evaporation, the impact of quantum effects, and the dynamics of inner horizons in charged or rotating black holes. We also study ultracompact black hole mimickers, especially black stars—semiclassical objects without singularities or horizons, potentially distinguishable from black holes via gravitational wave observations.

-Quantum geometry: Cosmology and Black Holes
We develop quantum gravity models emphasizing quantum geometry, primarily within canonical Loop Quantum Gravity (LQG), tensorial group field theory (TGFT) and spin foam models. LQG is a primary quantum gravity approach, reformulating general relativity as a gauge theory. TGFTs are QFTs for quantum spacetime constituents, that can also be seen as a 2nd quantized reformulation of LQG.
Our group applies LQG techniques to cosmological models and black hole spacetimes. In Loop Quantum Cosmology (LQC), the Big Bang singularity is replaced by a bounce, even with inhomogeneities, allowing for quantum corrections to the primordial power spectrum. We study as well quantum corrections to black-hole spacetimes motivated from LQG, and how those corrections might affect observables such as the spectrum of quasi-normal modes. We also explore emergent cosmological dynamics from quantum gravity models, in particular TGFTs, proposing a hydrodynamic framework that generalizes LQC, to address issues like the Big Bang, structure formation, and dark energy. We also investigate foundational questions in LQC, LQG and TGFT, such as the Problem of Time, with implications for cosmological evolution.
Our focus includes defining spacetime observables in a diffeomorphism-invariant language, exploring the continuum limit, and studying renormalization group flow. We aim to achieve a consistent continuum phase diagram for quantum gravity, using renormalization techniques like functional renormalization

- Emergent Gravity and Analogue Models
Our work on emergent gravity examines general relativistic analogues in condensed matter systems. We analyze whether these effective geometries could produce Einstein-like dynamics and whether emergent massless spin-2 excitations (gravitons) could manifest. We study the possibility of simulating cosmological dynamics in analogue systems, via the hydrodynamics extracted from quantum gravity models. We also explore the impact of Lorentz invariance violations at high energies, aiming to connect emergent gravity with effective field theories and relate our models to cosmological observations and laboratory simulations using analogue systems.

-Relativistic Quantum Information and Entanglement
Relativistic Quantum Information (RQI) uses field theory for quantum communication in relativistic settings, employing Unruh-DeWitt detectors to probe quantum field fluctuations. Our work includes studies of the Unruh effect and thermalization properties of detectors in various spacetime geometries, as well as detector responses near ultracompact objects. We also investigate entanglement among quantum geometric degrees of freedom in spin network states using tensor network methods in order to entanglement entropy for quantum gravity states, aiming to establish holographic maps.
We also study entanglement in QFT through quantum simulators in different scenarios. First, we explore entanglement generation in pair-creation phenomena such as the Hawking effect, superradiance, or pair-creation by expanding universes. Second, we also explore the possibility of using quantum fluid simulators as laboratories for the entanglement structure of vacuum and thermal states in QFT.

- Foundations of Physics and Philosophy of Science
We pursue conceptual inquiries into spacetime emergence, quantum mechanics foundations, and philosophy of science. Our focus includes the epistemological implications of quantum mechanics interpretations and the nature of physical laws. This exploration addresses broader issues like scientific realism, motivated by the distinct challenges of quantum gravity research

Quantum Fields in Curved Spacetimes
Black Holes and Semiclassical Gravity
Quantum geometry: Cosmology and Black Holes
Emergent Gravity and Analogue Models
Relativistic Quantum Information and Entanglement
Foundations of Physics and Philosophy of Science

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