SPACE Colloquium: Lucia Rizzuto - "Quantum Fields with Moving Boundaries"

Thursday 26 Mar 2026, 14:30 → 15:30 Europe/Rome

Via Mezzocannone 4

Abstract. The existence of field fluctuations in the vacuum state is a remarkable prediction of quantum field theory. These fluctuations have observable consequences such as the Casimir force between two neutral mirrors or dielectrics in vacuum or the Casimir-Polder interactions between two neutral atoms. The presence of a dielectric or reflecting boundary modifies the structure of the field modes and can change the expectation values of several local field observables, such as the field energy density, or the atom-surface dispersion interactions. New physical phenomena appear when we consider a dynamical, time dependent environment, such as oscillating cavities, moving mirrors, or dynamical photonic crystals. The presence of a moving boundary - for instance an oscillating mirror – can strongly affect the radiative properties of atoms or molecules placed nearby. In this talk, we will discuss some physical properties of the quantum electromagnetic field in the presence of a moving boundary, and the effects on the radiative properties of atoms placed nearby.

We will first consider one atom prepared in an excited state, and interacting with the quantum electromagnetic field in the vacuum state, in the presence of a plane mirror, that oscillates adiabatically. We show that the presence of the oscillating mirror changes the physical features of the spontaneous emission of the atom, in particular the emitted spectrum. This result indicates that dynamical (time-dependent) environments can be exploited to manipulate and control the radiative properties of atoms or molecules embedded in. We also investigate some physical properties of a quantum scalar field in the presence of a moving reflecting wall. Specifically, we consider two cavities separated by a mirror subjected to a harmonic potential and free to move around its equilibrium position, and investigate the quantum correlations between the massless scalar fields confined in the two cavities. The mechanical degrees of freedom of the movable mirror are included in the Hamiltonian description, which leads to an effective interaction between the field modes in the two half spaces mediated by the reflecting wall. We show that, while the spatial correlation between the field operators in the two half-spaces vanishes at any order, the correlations between the squared scalar fields in the two cavities are non-vanishing and in fact become anti-correlated starting from second order in the field–mirror coupling. We shall discuss that the existence of these anti-correlations can be interpreted as a form of indirect influence between the two half-spaces arising from the quantum motion of the perfectly reflecting mirror.

Bio. Lucia Rizzuto is Associate Professor of Theoretical Physics (PHYS-02/A) since 2022. She obtained the PhD in Physics and has been a permanent researcher from 2008 to 2022. She has authored more than 50 publications in ISI international journals. Her research interests include quantum electrodynamics, Casimir–Polder and dispersion interactions, Unruh effect, quantum electrodynamics in nanostructured materials.

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