A groundbreaking study from Technion has unveiled a newly discovered form of quantum entanglement in the total angular momentum of photons confined within nanoscale structures. This significant discovery has the potential to play a pivotal role in the future miniaturization of components used in quantum communication and quantum computing.
Quantum physics often leads to unconventional predictions, a phenomenon first highlighted in 1935 by Albert Einstein, alongside his colleagues Boris Podolsky and Nathan Rosen, who later founded the Faculty of Physics at Technion. Their landmark paper, known as the EPR paper, introduced a scenario where knowing the state of one particle instantaneously affects the state of another particle, regardless of the distance separating them.
Einstein famously referred to this phenomenon as “spooky action at a distance,” expressing his skepticism towards the implications of such quantum behavior. However, a pioneering study by Research Prof. Asher Peres from the Faculty of Physics demonstrated that this property could indeed be harnessed for the transmission of information through quantum teleportation, which forms the basis for modern quantum communication.
The phenomenon of quantum entanglement was later formally recognized for its profound implications, leading to the 2022 Nobel Prize in Physics awarded to Profs. Alain Aspect, Anton Zeilinger, and John Clauser. Their groundbreaking work on the subject has paved the way for advancements in both quantum computing and quantum communication, showcasing the versatility of entanglement across various particles and properties.
In the realm of photon behavior, quantum entanglement can manifest in various forms, including the direction of travel, frequency, and even more complex properties like angular momentum. Angular momentum can be divided into two types: spin, related to the photon's electric field rotation, and orbit, concerning the photon's movement through space. This duality is akin to Earth’s rotation on its axis and its orbit around the sun.
However, when researchers attempt to confine photons within structures smaller than their photonic wavelength—an area of study known as nanophotonics—they find that it becomes impossible to separate these rotational properties. Instead, photons become characterized by a single quantity known as total angular momentum.
Why is confining photons in such tiny structures important? There are two primary reasons. First, miniaturizing devices that utilize light will enable more operations to be performed in a smaller area, mirroring the evolution of electronic circuits. More critically, this miniaturization enhances the interaction between photons and the materials they encounter, leading to the emergence of novel phenomena and applications that are unattainable with photons in their conventional dimensions.
In a study published in the journal Nature, Technion researchers, led by Ph.D. student Amit Kam and Dr. Shai Tsesses, have successfully demonstrated that photons can be entangled within nanoscale systems that are a thousandth the width of a human hair. Remarkably, this entanglement occurs not through conventional properties such as spin or trajectory, but solely via total angular momentum.
The researchers meticulously detailed the process that photons experience from their introduction into these nanoscale systems to their eventual exit, revealing that this transition enriches the range of states available to the photons. Through a series of measurements, they successfully mapped these states, entangled them with the unique properties of nanoscale systems, and confirmed the correlation between photon pairs indicative of quantum entanglement.
This pivotal research from Technion not only enhances our understanding of quantum entanglement but also opens new avenues for the development of quantum technologies. As the field of nanophotonics continues to evolve, the insights gained from this study are likely to drive significant advancements in both quantum communication and quantum computing, paving the way for future innovations.
