A team of physicists at the University of Rochester, led by Professor Regina Demina, has recently conducted an experiment at the European Center for Nuclear Research (CERN) that has produced a significant result relating to quantum entanglement. The team has confirmed that entanglement persists between unstable top quarks and their antimatter partners at distances much farther than what can be covered by information transmitted at the speed of light. This finding is a testament to what Albert Einstein called “spooky action at a distance” and could have far-reaching implications in the field of quantum information science.

Entanglement is a coordinated behavior of minuscule particles that occurs when they interact and then move apart. Even when separated, the measurement of a single particle’s properties, such as position, momentum, or spin, instantaneously affects the results of the other particle, thus making their states seemingly inseparable. Until now, quantum entanglement has been observed only between stable particles, such as electrons and photons. This study has broken new ground by observing the phenomenon between unstable particles called top quarks.

The finding, reported by the Compact Muon Solenoid (CMS) Collaboration, confirmed quantum entanglement between the heaviest fundamental particles – top quarks. The researchers’ findings have opened up a new avenue for exploration of the quantum nature of the world at energies beyond what is currently accessible. CERN, based near Geneva, Switzerland, enabled this breakthrough through the Large Hadron Collider (LHC), which facilitates research by discharging high-energy particles around a 17-mile underground track at speeds approaching that of light.

While entanglement forms the foundation of quantum information science, the discovery of persistent entanglement between top quarks and antimatter is unlikely to be applied to building a quantum computer. However, research like that conducted by Demina and her team sheds light on how long entanglement persists and what ultimately breaks it. This study can contribute significantly to our understanding of what led to the loss of the quantum connection in our world, and theorists believe that the universe was in an entangled state after the initial fast expansion stage.

The researchers achieved these noteworthy results by confirming the spin correlation between top quarks and their antimatter partners, thereby manifesting what Einstein called “spooky action at a distance.” The discovery has provided new insight into the persistence of quantum entanglement.

Regina Demina, the leader of the study, recorded a video for CMS' social media channels, where she explains her group’s result using an analogy of an indecisive king of a distant land referred to as “King Top.” The concept enables the viewer to understand the relationship between Anti-Top, King Top’s antiparticle, and the entangled state of their minds at any moment in time.

Demina’s research group consisted of herself, graduate student Alan Herrera, and postdoctoral fellow Otto Hindrichs. As a graduate student, Demina was part of the team that discovered the top quark in 1995 and co-led a team of scientists from across the US that designed a tracking device, playing a crucial role in the 2012 discovery of the Higgs boson.

The study positions the University of Rochester's research at the forefront of the field of particle physics. The research conducted at CERN continues to expand our understanding of the nature of the universe, with the findings contributing to the growth of the rapidly growing field of quantum information science.

A team of researchers at the University of California, Riverside, has made a significant breakthrough in understanding and utilizing ultra-fast spin behavior in ferromagnets. This research, featured in Physical Review Letters, opens the door for the development of high-frequency applications that could revolutionize future communication and computation technologies.

Currently, smartphones and computers operate at gigahertz frequencies, but there is a push to make them even faster. This research suggests that it may be possible to achieve terahertz frequencies using conventional ferromagnets, which could lead to communication and computation technologies operating at speeds a thousand times faster than current benchmarks.

Ferromagnets, which have electrons with aligned spins, exhibit a phenomenon called "spin waves," which are crucial for processing information and signals in emerging computer technologies.

Dr. Igor Barsukov, an associate professor of physics and astronomy at UC Riverside, explained that the interaction of electron spins with electrons and the crystal lattice of ferromagnets causes them to experience friction. This friction leads to the acquisition of inertia by the spins, resulting in an additional form of spin oscillation called nutation, which occurs at ultra-high frequencies and holds great promise for future computer and communication technologies.

The study also highlighted the potential of nutational auto-oscillations generated by injecting a spin current with the "wrong" sign, as explained by the first author of the paper, a graduate student in the Barsukov Group and scientist at HRL Labs, LLC.

Coauthor Allison Tossounian, previously an undergraduate student in the Barsukov Group, recognized the promise of these self-sustained oscillations for the next generation of computation and communication technologies.

Dr. Barsukov emphasized the impact of introducing a second-time derivative in the equation of motion by spin inertia, leading to the emergence of counterintuitive phenomena. By harmonizing spin-current-driven dynamics and spin inertia, and identifying similarities between the spin dynamics in ferromagnets and ferrimagnets, the study could accelerate technological innovation by leveraging synergies between these fields.

Additionally, Dr. Barsukov highlighted the growing interest in ferrimagnets, which have two antiparallel spin lattices with an unequal amount of spin, as potential candidates for ultrafast applications.

While acknowledging ongoing technological challenges, Dr. Barsukov pointed out significant advances in understanding spin currents and materials engineering for ferromagnets over recent decades. These developments, combined with the confirmation of nutation, have paved the way for ferromagnets to emerge as leading contenders for ultra-high frequency applications.

The study, titled "Spin inertia and auto-oscillations in ferromagnets," received support from the National Science Foundation.