arXiv subjects

Fabrizio Preda

Publications and source records attributed to Fabrizio Preda.

3 recordsLinked to original sources

arXiv2026

Coherent multi-dimensional widefield microscopy

Understanding how electronic excitations evolve across space and time is essential for revealing the microscopic processes underlying quantum and optoelectronic materials. However, existing approaches cannot simultaneously resolve ultrafast coherent dynamics with microscopic spatial information: pump-probe microscopy lacks access to quantum coherence, while two-dimensional electronic spectroscopy (2DES) requires slow point-by-point scanning for spatial resolution. Here we introduce a widefield two-dimensional electronic spectroscopy microscope (2DESM) combining multidimensional coherent spectroscopy with widefield imaging, enabling simultaneous femtosecond temporal and micrometer spatial resolution across a broadband spectral range. Applying 2DESM to hBN-encapsulated WSe2, we directly visualize spatial variations in exciton coherence and relaxation associated with the local environment, establishing 2DESM as a powerful platform for probing many-body interactions, energy transport, and structure-function relationships in low-dimensional materials and devices.

physics.optics↗

arXiv2023

Measurement principles for quantum spectroscopy of molecular materials with entangled photons

Nonlinear spectroscopy with quantum entangled photons is an emerging field of research that holds the promise to achieve a superior signal-to-noise ratio and effectively isolate many-body interactions. Photon sources used for this purpose however lack the frequency tunability and spectral bandwidth demanded by contemporary molecular materials. Here, we present design strategies for efficient spontaneous parametric downconversion to generate biphoton states with adequate spectral bandwidth and at visible wavelengths. Importantly, we demonstrate, by suitable design of the nonlinear optical interaction, the scope to engineer the degree of spectral correlations between the photons of the pair. We also present an experimental methodology to effectively characterize such spectral correlations. Importantly, we believe that such a characterization tool can be effectively adapted as a spectroscopy platform to optically probe system-bath interactions in materials.

physics.optics↗

arXiv2020

Tuning the Ultrafast Response of Fano Resonances in Halide Perovskite Nanoparticles

The full control of the fundamental photophysics of nanosystems at frequencies as high as few THz is key for tunable and ultrafast nano-photonic devices and metamaterials. Here we combine geometrical and ultrafast control of the optical properties of halide perovskite nanoparticles, which constitute a prominent platform for nanophotonics. The pulsed photoinjection of free carriers across the semiconducting gap leads to a sub-picosecond modification of the far-field electromagnetic properties that is fully controlled by the geometry of the system. When the nanoparticle size is tuned so as to achieve the overlap between the narrowband excitons and the geometry-controlled Mie resonances, the ultrafast modulation of the transmittivity is completely reversed with respect to what is usually observed in nanoparticles with different sizes, in bulk systems and in thin films. The interplay between chemical, geometrical and ultrafast tuning offers an additional control parameter with impact on nano-antennas and ultrafast optical switches.

cond-mat.mtrl-sci↗