CERN’s CMS detector observes quantum entanglement at highest energy ever
2024-09-18
Purdue researchers on the CMS team led early indicators that proves high-energy colliders are useful tools for measuring and observing entanglement
The romantic notion of entangled particles presumes that once two particles become entangled, they are forever bonded no matter how far apart from one another they are. This relationship has puzzled physicists ever since Erwin Schrödinger coined the term “entanglement” in 1935. Though scientists have observed this phenomenon in many ways, there has been no research at high energies such as provided by large-scale labs like the Large Hadron Collider.
In an article published today in Nature, the ATLAS collaboration reports how it succeeded in observing quantum entanglement at the LHC for the first time, between fundamental particles called top quarks at the highest energies yet. First reported by ATLAS in September 2023 and confirmed in March 2024 by the CMS collaboration, this result has opened up a new perspective on the complex world of quantum physics. This discovery includes four researchers from Purdue University’s College of Science.
In a CERN press release, ATLAS and CMS teams observed quantum entanglement between a top quark and its antimatter counterpart. The observations follow a recent proposal of using pairs of top quarks produced at the LHC as a new system to study entanglement.
Modern day scientists see great potential in the behavior of entangled particles because of their vast potential in quantum mechanics. The CMS is a general-purpose detector that sits at one of the four collision points of the Large Hadron Collider, the largest and most powerful particle accelerator ever built. Researchers have recently begun using the CMS detector to study quantum entanglement. Andreas Jung, associate professor of Physics and Astronomy at the Purdue University College of Science, led a team of researchers that used the CMS data to form the early discovery of the observed quantum entanglement.
This result is also featured in a Nature News article highlighting the details of the data analysis done by the Purdue group.
Jung is the Principal Investigator and leader of the analysis team dedicated to the measurement of top quark quantum entanglement using CMS data. He served as the CMS TOP physics analysis group convener in 2020-2022 and his group is also a major contributor to the CMS detector upgrade of the silicon tracking devices.
“Entanglement is a new probe to study quantum mechanics at fundamental level and to understand bare top quark properties in order to reveal beyond the Standard Model contributions,” he says.
"While particle physics is deeply rooted in quantum mechanics, the observation of quantum entanglement in a new particle system and at much higher energy than previously possible is remarkable,” says ATLAS spokesperson Andreas Hoecker. “It paves the way for new investigations into this fascinating phenomenon, opening up a rich menu of exploration as our data samples continue to grow."
Jung’s team included Giulia Negro, a postdoc, and two PhD candidates: Andrew J Wildridge and Lingqiang He, all from Purdue University. The CMS internal review was led by the Analysis Review Committee chair Javier F. Menendez (Oviedo U.), and CMS TOP physics analysis group conveners Alexander Grohsjean (DESY), Jan Kieseler (KIT). "After a thorough internal review, we are very happy to see this measurement being released to the public", comment the CMS top group conveners Alexander Grohsjean (DESY) and Jan Kieseler (KIT).
Negro is currently the detector performance group coordinator, as well as the Deputy Run Coordinator of the CMS detector and hence, plays a critical role in overseeing the large complex task of CMS detector operation. As such, she is part of the CMS Management Board. In 2021, she received a CMS award in recognition of “crucial contributions to the refurbishment and the operation of the CMS Pixel Detector.” She is also a recipient of the Ross-Lynn Fellowship at Purdue University.
"It's fascinating how the largest accelerator on earth can enable us not only to probe the Standard Model of particle physics but also to explore fundamental quantum mechanics effects," says Negro.
“This measurement showing that the top quarks are indeed entangled is exciting to me because it is paving the way for the fascinating ideas in quantum information theory to be applied and studied on fundamental particles beyond the electron and photon,” says Wildridge, who is involved in the analysis of the data.
Jung’s team authored early results from this study at the beginning of this year. At that time, they were hoping the CMS results would confirm the earlier ATLAS findings. “The new CMS result confirms the existence of entanglement between the top quark and its antiparticle beyond reasonable doubt,” says Jung. “The two states are found entangled with a significance exceeding the famous five standard deviations discovery threshold and in agreement with the Standard Model prediction.”
This giant leap in quantum particle physics aligns with a mission from Purdue University. Quantum science and engineering is one of four dimensions within Purdue Computes, a major initiative that enables the university to advance to the forefront with unparalleled excellence at scale. The team plans to move forward with more research with the CMS detector and this discovery throws the doors open for new discoveries.
“The results also open new paths in the particle-physics arena,” says CMS spokesperson Patricia McBride in CERN’s press release. “With measurements of entanglement and other quantum concepts at an energy range beyond what was previously accessible, we can test the Standard Model of particle physics in new ways and look for any signs of new physics that may lie beyond it.”
According to Jung, “Quantum information at particle colliders is a new exciting field of research, which is now producing six times the number of papers on preprint servers (arXiv) compared to ten years ago. It allows us to challenge our understanding of quantum field theories with many prospects to discover new physics and phenomena.”
This research is funded by the U.S. Department of Energy program under Award Number(s) DE-SC0007884 titled "An Experimental and Theoretical High Energy Physics Program" and under Award Number(s) DE-SC00023700 titled "AI for a more precise future of the top quark."
About the Department of Physics and Astronomy at Purdue University
Purdue’s Department of Physics and Astronomy has a rich and long history dating back to 1904. Our faculty and students are exploring nature at all length scales, from the subatomic to the macroscopic and everything in between. With an excellent and diverse community of faculty, postdocs and students who are pushing new scientific frontiers, we offer a dynamic learning environment, an inclusive research community and an engaging network of scholars.
Physics and Astronomy is one of the seven departments within the Purdue University College of Science. World-class research is performed in astrophysics, atomic and molecular optics, accelerator mass spectrometry, biophysics, condensed matter physics, quantum information science, and particle and nuclear physics. Our state-of-the-art facilities are in the Physics Building, but our researchers also engage in interdisciplinary work at Discovery Park District at Purdue, particularly the Birck Nanotechnology Center and the Bindley Bioscience Center. We also participate in global research including at the Large Hadron Collider at CERN, many national laboratories (such as Argonne National Laboratory, Brookhaven National Laboratory, Fermilab, Oak Ridge National Laboratory, the Stanford Linear Accelerator, etc.), the James Webb Space Telescope, and several observatories around the world.
About Purdue University
Purdue University is a public research institution demonstrating excellence at scale. Ranked among top 10 public universities and with two colleges in the top four in the United States, Purdue discovers and disseminates knowledge with a quality and at a scale second to none. More than 105,000 students study at Purdue across modalities and locations, including nearly 50,000 in person on the West Lafayette campus. Committed to affordability and accessibility, Purdue’s main campus has frozen tuition 13 years in a row. See how Purdue never stops in the persistent pursuit of the next giant leap — including its first comprehensive urban campus in Indianapolis, the Mitch Daniels School of Business, Purdue Computes and the One Health initiative — at https://www.purdue.edu/president/strategic-initiatives.
Contributors:
Andreas Jung, associate professor of physics and astronomy at the Purdue University College of Science
Giulia Negro, postdoc at Purdue Physics and Astronomy
Andrew J Wildridge, PhD candidate at Purdue Physics and Astronomy
Lingqiang He, PhD candidate at Purdue Physics and Astronomy
Written by Cheryl Pierce, Lead Marketing and Public Relations Specialist at the Purdue University College of Science