CERN observes quantum entanglement at the highest energy so far
QUANTUM entanglement is a fascinating feature of quantum physics. If two particles are quantum-entangled, the state of one particle is tied to that of the other, no matter how far apart the particles are.
This phenomenon, which has no analogue in classical physics, has been observed in a wide variety of systems and has found several important applications, such as quantum cryptography and quantum computing.
In 2022, the Nobel Prize in Physics was awarded to Alain Aspect, John F. Clauser, and Anton Zeilinger for groundbreaking experiments with entangled photons. These experiments confirmed the predictions made by the late theorist John Bell.
Entanglement has remained largely unexplored at the high energies accessible at particle colliders such as the Large Hadron Collider (LHC). In the latest issue of Nature, the ATLAS collaboration at the LHC has reported that it has observed quantum entanglement for the first time between fundamental particles called top quarks and at the highest energies yet. ATLAS has now reconfirmed the result that it first reported in September 2023. Meanwhile, the CMS collaboration has also succeeded in observing entanglement between top quarks.
The ATLAS and CMS teams observed quantum entanglement between a top quark and its antimatter counterpart. The top quark is the heaviest known fundamental particle. To observe entanglement between top quarks, the ATLAS and CMS collaborations selected pairs of top quarks from data of proton-proton collisions at an energy of 13 tera-electronvolts between 2015 and 2018. In particular, they looked for pairs in which the two quarks are simultaneously produced with low momentum relative to each other. This is when the spins of the two quarks are expected to be strongly entangled.
The second study by CMS also looked for pairs of top quarks in which the two quarks are simultaneously produced with a high momentum relative to each other. In this domain, for a large fraction of top quark pairs, the relative positions and times when the two top quarks decay are such that classical exchange of information by particles travelling at less than the speed of light is excluded. CMS observed spin entanglement between top quarks in this case also.
The existence and degree of spin entanglement can be inferred from the angle between the directions in which the charged decay products of the two quarks are emitted
Breastfeeding possible even after breast cancer
IN recent years, numerous studies have demonstrated that pregnancy is possible and safe following breast cancer, even with the use of assisted reproductive technologies. However, because many breast cancers are hormone responsive, doctors were concerned about potential risks in breastfeeding following breast cancer due to the changes that occur in the hormonal status during pregnancy and lactation. “These considerations also apply to women carrying a BRCA gene mutation who have an increased risk of cancer in the contralateral breast,” Eva Blondeaux of IRCCS Ospedale Policlinico San Martino in Genoa, Italy, was quoted as saying by Medscape, an online medical news platform.
Now, two international studies led by Italian researchers have found that breastfeeding is safe even after breast cancer. The findings were presented at the European Society for Medical Oncology Congress 2024 held in Barcelona, Spain, from September 13 to 17. “Before this data, doctors tended to be cautious, if not outright defensive, about the possibility and safety of breastfeeding [following breast cancer],” Fedro Alessandro Peccatori, of the European Institute of Oncology in Milan, Italy, and lead author of a study that reported results from a trial called POSITIVE, told Medscape
Blondeaux was involved in the second study involving women who have the BRCA mutation.
The POSITIVE study involved 518 women (from 116 institutions in 20 countries across four continents) with hormone receptor-positive breast cancer who had temporarily stopped adjuvant hormonal treatment to become pregnant. The study found no significant differences in the rates of recurrence at 24 months or new breast cancer between women who breastfed and those who did not. The second study involved 4,732 women recruited from 78 international centres who were diagnosed with breast cancer at a young age and were carriers of a BRCA gene mutation. Importantly, about half of them had undergone preventive bilateral mastectomy before giving birth. In this study too, breastfeeding did not show significant differences between groups in terms of local recurrences or development of second contralateral breast cancer.
An artist’s illustration of the longest black hole jet system ever observed. | Photo Credit: E. Wernquist/D. Nelson (TNG Collaboration)/M. Oei
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Gargantuan black hole jets are biggest seen yet
ASTRONOMERS have spotted the biggest pair of black hole jets ever seen, spanning 7 megaparsecs, or 23 million light years, in total length. “The Milky Way would be a little dot in these two giant eruptions,” said Martijn Oei of Caltech and the lead author of the paper titled “Black hole jets on the scale of the cosmic web”, which was published recently in Nature. Nicknamed Porphyrion after a giant in Greek mythology, the jet megastructure dates to a time when our universe was 6.3 billion years old, or less than half its present age of 13.8 billion years. These fierce outflows, with a total power output equivalent to trillions of suns, are seen to shoot out from above and below a supermassive black hole at the heart of a remote galaxy.
The latest finding, according to the release from Caltech, suggests that these giant jet systems may have had a larger influence on the formation of galaxies in the young universe than previously believed. Porphyrion existed during an early epoch when the wispy filaments that connect and feed galaxies, known as the cosmic web, were closer together than they are now. That means enormous jets like Porphyrion reached across a greater portion of the cosmic web compared with jets in the local universe.
“Astronomers believe that galaxies and their central black holes co-evolve, and one key aspect of this is that jets can spread huge amounts of energy that affect the growth of their host galaxies and other galaxies near them,” said co-author George Djorgovski of Caltech. “This discovery shows that their effects can extend much farther out than we thought.” To find the galaxy from which Porphyrion originated, the team used the Giant Metrewave Radio Telescope of the Tata Institute of Fundamental Research located near Pune along with ancillary data from a project called Dark Energy Spectroscopic Instrument, which operates from the Kitt Peak National Observatory in Arizona. The observations pinpointed the home of the jets to a hefty galaxy about 10 times more massive than our Milky Way.
