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(Nanowerk News) The question of where the boundary lies between classical and quantum physics is one of the oldest quests in modern scientific research, and in new research, scientists demonstrate a novel platform that could help us find an answer.
The laws of quantum physics govern the behavior of particles at tiny scales, leading to phenomena such as quantum entanglement, where the properties of entangled particles become inextricably linked in ways that classical physics cannot explain.
Research in quantum physics helps us fill gaps in our knowledge of physics and can give us a more complete picture of reality, but the small scales at which quantum systems operate can make them difficult to observe and study.
Over the past century, physicists have successfully observed quantum phenomena in increasingly larger objects, from subatomic particles like electrons to molecules containing thousands of atoms.
More recently, the field of levitation optomechanics, which deals with the control of large-mass objects at the micrometer scale in a vacuum, aims to go further by testing the validity of quantum phenomena in objects that are several orders of magnitude heavier. than atoms and molecules. However, as the mass and size of an object increase, the interactions that give rise to delicate quantum features, such as entanglement, are lost to the environment, giving rise to the classical behavior we observe.
But now, the team co-led by Dr. Jayadev Vijayan, head of the Quantum Engineering Laboratory at the University of Manchester, with scientists from ETH Zurich and theorists from the University of Innsbruck, has established a new approach to overcome this problem in a way experiment carried out at ETH Zurich, published in the journal Nature physics (“Long-range cavity-mediated interactions in levitated optomechanics”).
Dr. Vijayan said, “To observe quantum phenomena at larger scales and shed light on the classical quantum transition, it is necessary to preserve quantum characteristics in the presence of environmental noise. As you can imagine, there are two ways to do this: one is to suppress the noise and the second is to boost the quantum functions.
“Our research demonstrates one way to address the challenge by taking the second approach. “We show that the interactions necessary for entanglement between two optically trapped 0.1-micron glass particles can be amplified by several orders of magnitude to overcome losses to the environment.”
The scientists placed the particles between two highly reflective mirrors that form an optical cavity. In this way, the photons scattered by each particle bounce between the mirrors several thousand times before leaving the cavity, significantly increasing the chances of interacting with the other particle.
Johannes Piotrowski, co-leader of the paper from ETH Zurich, added: “Surprisingly, because the optical interactions are mediated by the cavity, their strength does not decrease with distance, meaning we could couple micrometer-scale particles down to several millimeters.”
The researchers also demonstrate the remarkable ability to precisely tune or control the interaction force by varying the laser frequencies and the position of the particles within the cavity.
The findings represent a significant leap toward understanding fundamental physics, but also hold promise for practical applications, particularly in sensor technology that could be used for environmental monitoring and offline navigation.
Dr. Carlos González-Ballestero, collaborator at the Technical University of Vienna, said: “The key advantage of levitated mechanical sensors is their large mass relative to other quantum systems that use sensors. The large mass makes them well suited for detecting gravitational forces and accelerations, resulting in better sensitivity. “As such, quantum sensors can be used in many different applications in various fields, such as monitoring polar ice for climate research and measuring accelerations for navigation purposes.”
Piotrowski added: “It’s exciting to work on this relatively new platform and test how far we can push it into the quantum regime.”
Now, the team of researchers will combine the new capabilities with well-established quantum cooling techniques in a step toward validating quantum entanglement. If successful, achieving levitated nanoparticle and microparticle entanglement could narrow the gap between the quantum world and everyday classical mechanics.
At the Photon Science Institute and the Department of Electrical and Electronic Engineering at the University of Manchester, Dr Jayadev Vijayan’s team will continue to work on levitated optomechanics, harnessing interactions between multiple nanoparticles for applications in quantum sensing.