PRESS RELEASE 2024

The ultracold atoms lab of the Pitaevskii Center for Bose-Einstein Condensation in Trento reports for the first time the observation of phenomena related to the stability of our universe. The results arise from the collaboration among the National Institute of Optics of Cnr, the Physics Department of the University of Trento, Tifpa-Infn and the University of Newcastle and it has been published in Nature Physics.

In which kind of vacuum is our universe? Modern physics describes our universe as an intricate outcome of the interactions between particles and fields (the electromagnetic one, for example). From a general point of view, our universe could be in a not so stable configuration, known as false vacuum, which has an energy higher than the absolute minimum. So, in principle it could decay to the lowest energy state, the true vacuum, triggered by quantum or thermal fluctuations.

False vacuum decay could take place on very different time scales, depending on the system parameters and it manifests with the appearance of bubbles of true vacuum, similarly to the formation of liquid drops in a gas cooled below the condensation point. This process is strongly related to cosmological phenomena and the research community has dedicated great effort to understand in which kind of vacuum our universe is. Several research groups have developed sophisticated theories to describe this process, and, in the absence of a direct access to the conditions of the Big Bang, table top experimental platforms for testing and simulating these models have been devised.

 Today the first observation of this decay is reported in a study published on Nature Physics and with Alessandro Zenesini (Pitaevskii BEC Center, Istituto nazionale di ottica del Consiglio nazionale delle ricerche e Dipartimento di Fisica dell’Università di Trento, Tifpa Trento Institute for Fundamental Physics and Applications, INFN as first author. Researchers prepared a cloud of sodium atoms in an initial state which looks like a false vacuum. They then measured the time it takes to the system to decay to the real vacuum, under different experimental conditions. After a first comparison with numerical simulations of the system, the authors joined the theory group of Ian Moss, well known cosmologist which has also collaborated with Stephen Hawking, to verify that the most reliable theory of false vacuum decay is compatible with the observations.

Once again, ultracold atoms prove to be an ideal platform for quantum simulation both of the extremely small and the extremely large. “We used the magnetic properties of atoms to create artificial false and true vacuum in an ultra-stable and controllable environment. This exquisite control of the degenerate atomic cloud allows us to study false vacuum decay in different experimental conditions and to compare our results with theoretical predictions.” reports Alessandro Zenesini, Cnr-Ino researcher who collaborated for this research with Giacomo Lamporesi and Alessio Recati from the same institute. 

“False vacuum decay theories were developed more than fifty years ago having in mind processes typical of high-energy and subnuclear physics and cosmology.” says Gabriele Ferrari (UniTrento). “The results are a first step toward the validation of theories which were only on paper, and pave the road to new lines of experimental research on the different aspects of the birth and dynamics of the true vacuum bubble, with also effects on biochemistry and quantum computation.”

This research was funded by Provincia Autonoma di Trento, INFN, MUR, Q@TN, UK Quantum Technologies programme and European Union.

The prestigious 2024 Bruno Rossi prize of the High Energy Astrophysics Division (HEAD) of the American Astronomical Society was awarded to Martin Weisskopf, Paolo Soffitta, and to the scientific collaboration of the IXPE mission “for their development of the Imaging X-ray Polarimetry Explorer whose novel measurements advance our understanding of particle acceleration and emission from astrophysical shocks, black holes and neutron stars”. Launched in December 2021, IXPE is making an amazing contribution to our understanding of the mechanisms of many processes that occur in our universe thanks to its new, rich, and detailed measurements. In particular, IXPE added two observables, the degree and angle of polarization simultaneously with the more usual spatial coordinate, temporal coordinate, and energy. This underlies the success of IXPE that undertook very important research in the field of acceleration phenomena in the most brilliant pulsar wind nebulae and blazars. It also made it possible to study turbulence phenomena and shocks in the remains of supernovae, mapping their magnetic field in close proximity to acceleration sites. The energy-resolved polarization analysis made it possible to study the plasma near the most brilliant galactic black holes and the galactic centre, and near those supermassive black holes of the active galaxies. The time-resolved polarization analysis then made it possible, for the first time, to directly measure the geometry of the binary pulsars and isolated pulsars such as the magnetar. Such parameters are sometimes degenerated by the usual spectroscopy and temporal variability analyses. All these extraordinary results that IXPE has already managed to obtain in just a few months’ work are behind the prestigious recognition just awarded by the American Astronomical Society. 

The scientific collaboration Event Horizon Telescope (EHT), which published the first “photo” of a black hole in 2019, has published new images of M87*, the supermassive black hole at the centre of the Messier 87 galaxy. This time, the images were created from observations taken in April 2018, one year after the data that led to the image released in 2019. Thanks to the contribution of a new telescope, the Greenland Telescope, and to a clearly improved data acquisition rate in all EHT network telescopes, the 2018 observations offer a vision of the source that is independent from the first observations in 2017. The new images were made by an international research group, in which researchers of the National Institute for Astrophysics (INAF), INFN, the University of Naples Federico II and the University of Cagliari participate. They were recently published in the Astronomy & Astrophysics journal. The images reveal a luminous ring, of the same dimensions as the one observed in 2017, which surrounds a deep central depression, the shadow of the black hole, as predicted by general relativity. What is different is the position of the brightest peak of the ring, which has moved by approximately 30° compared to the images from 2017. This is in line with our theoretical understanding of the variability of turbulent material around black holes.

EHT Collaboration press release

Paper on Astronomy & Astrophysics

An entirely Italian research group composed of scientists of the National Institute for Astrophysics (INAF), the University of Florence, and INFN started analysing two samples of the Ryugu asteroid. These were received in May 2023 as part of an international competition for analysing cosmic material brought back to Earth by the Hayabusa-2 mission of the Japan Aerospace Exploration Agency (JAXA).

The first infrared spectroscopy investigations were conducted in the synchrotron light laboratory Dafne Luce of the INFN Frascati National Laboratories, exploiting the radiation produced by the Laboratories’ particle accelerator, Dafne. With these first analyses, the research group is focusing on studying the mineralogy, organic matter, and water of the samples to obtain the first information from these fossils of the solar system. The fragments probably date back to the very early phases of the formation of our planetary system, i.e. to approximately four billion years ago. After the analyses at the INFN Frascati Laboratories, the Ryugu samples will be brought to the University of Florence for further investigations aimed at acquiring more information on their history.