The work, titled "Quantum states in cosmological spacetimes and entanglement in quantum field theory", was defended in 2024 and addresses fundamental questions about the nature of the quantum vacuum, the expansion of the universe, and correlations between different regions of space. The thesis was developed at the Institute of Corpuscular Physics (IFIC), a joint center of the CSIC and the Universitat de València, integrated into the scientific-academic area of the Parc Científic de la Universitat de València (PCUV).
Unlike classical physics, where vacuum is associated with the absence of matter, quantum theory posits that even the lowest energy state of a field contains fluctuations. These can exhibit correlations between separated regions, a phenomenon known as quantum entanglement. One of the challenges arises when studying the expanding universe, where there isn't a single way to define the vacuum state, which has implications for physical predictions.
Nadal has developed methods to identify physically relevant vacuum states and regularize observable quantities using renormalization techniques. The second part of the research focuses on how quantum correlations are distributed across finite regions of space, analyzing the structure of vacuum entanglement.
The award recognizes doctoral research conducted at IFIC, a center that has recently seen another doctoral thesis distinguished. Sergi Nadal Gisbert, originally from Vall d'Alcalà and born in Alcoy in 1996, graduated in Physics from the Universitat de València and completed a Master's in Advanced Physics. His career includes international stays in Poland, the United States, Canada, and the United Kingdom.
The Extraordinary Doctorate Awards from the Universitat de València annually distinguish doctoral theses that stand out for their scientific quality. The award to Nadal Gisbert recognizes research focused on the nature of the vacuum, the behavior of quantum fields in a dynamic universe, and the properties of entanglement.
