Quantum entanglement is one of the most puzzling and powerful concepts of quantum physics. It happens when two particles become so closely connected that whatever happens to one instantly affects the other, even if they\u2019re separated by vast distances.<\/p>\n
It\u2019s like having a pair of magical dice: if you roll one and it shows a six, the other one instantly shows a six, too, no matter if it\u2019s right next to you or on the other side of the galaxy. This weird connection doesn\u2019t make sense with everyday logic, but it\u2019s real and has been proven in experiments.\u00a0<\/p>\n
Until now, scientists believed that quantum entanglement<\/a> occurs through properties such as spin, position, velocity, etc. However, a new study from researchers at the Technion (Israel Institute of Technology) introduces a new type of entanglement that is carried out by a photon\u2019s angular momentum.\u00a0<\/p>\n \u201cThis is the first discovery of a new quantum entanglement in more than 20 years, and it may lead in the future to the development of new tools for the design of photon-based quantum communication and computing components, as well as to their significant miniaturization,\u201d the Technion team notes<\/a>.<\/p>\n Quantum entanglement with a twist<\/p>\n There are different ways to entangle a photon. This can happen through the direction in which a photon moves, its frequency, or the way its electric field is oriented.\u00a0<\/p>\n One less familiar but important property is angular momentum, which describes how a photon spins or twists as it travels. Angular momentum<\/a> has two parts: one describes how the photon\u2019s electric field rotates (called spin), and the other relates to how the photon itself moves in a spiral through space (called orbital angular momentum).<\/p>\n Surprisingly, this quantum phenomenon is quite similar to how Earth moves. Our planet also spins on its axis and, at the same time, revolves around the Sun.\u00a0<\/p>\n Typically, spin and orbital motion are separable. However, during their study, the researchers discovered that when photons are entangled in nanoscale systems, the two parts of angular momentum merge and exist as a single property called total angular momentum.\u00a0<\/p>\n The study authors made photons enter<\/a>, move through, and exit a nanoscale system a thousand times smaller than the width of a human hair. The experiment showed that, in this particular case, quantum entanglement didn\u2019t involve the traditional properties (such as position or spin) but occurred through the total angular momentum.<\/p>\n When the researchers mapped the different quantum states resulting from this new type of entanglement, they noticed that photons could now exist in more possible ways than before.\u00a0<\/p>\n Why does it matter?<\/p>\n Using photons in extremely tiny structures might seem unnecessary at first, but there are two important reasons scientists are doing it. First, just like miniaturizing electronic parts<\/a> led to the development of powerful smartphones and laptops, shrinking light-based components can help build compact optical devices that do more in less space.<\/p>\n For example, this approach could be used to create efficient and practical tiny on-chip optical modulators<\/a>, tiny devices that control how light signals are sent through a computer chip. These modulators are used in high-speed data communication, like the kind needed in data centers or future quantum networks.<\/p>\n Another reason is that when photons are confined in a small space, they interact strongly with the material hosting them. This stronger interaction can lead to new behaviors and effects that aren\u2019t possible when light travels freely in larger systems. This could allow scientists to build more secure and reliable photon-based quantum computers and communication technologies<\/a>.\u00a0<\/p>\n Further research could shed more light on this new type of quantum entanglement and its applications.<\/p>\n