Four Israeli professors and doctoral students from the Technion-Israel Institute of Technology in Haifa have published an article in the prestigious journal, Science, about a groundbreaking device they call “a cannon for entangled light particles” for the study of quantum theory.
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The innovation was developed in the laboratory of Prof. David Gershoni of the Technion’s Faculty of Physics, in cooperation with doctoral students Ido Schwartz and Dan Cogan, and Prof. Nathaniel Lindner.
Their recent article, entitled, “Deterministic Generation of a Cluster State of Entangled Photons,” already praised by fellow physicists, represents a scientific breakthrough in quantum theory and has the potential to influence the future of communications, encryption and computerization.
In developing this device, Gershoni and his colleagues have tackled a major problem in attempts to develop quantum computers, coming closer to resolving the issue of how to create qubit units in an initiated and controlled manner to enable construction of such a computer.
The Israeli scientists have succeeded in creating “clusters” of photons, which are mutually entangled and crucial for many applications that require quantum information.
The device at the core of their experiment is called a “quantum dot,” a tiny block, several tens of nanometers in size, and comprised of a semiconductor embedded in another type of semiconductor.
The researchers used various optical and electrical means to cause the emission of photons at specified times. Gershoni’s breakthrough is in effect the first “cannon” that emits many entangled photons on demand.
In quantum physics the world is described by means of wave functions, which describe the probability of detecting a given particle in a given place at a given time. Quantum physics will never tell you where the particle will be found, but only the probability of its being located in the abovementioned spot.
Understanding quantum theory led to the flourishing of a new scientific field called “quantum information processing,” based on the understanding that information processing saved on quantum systems differs from information processing carried out on systems that behave according to the laws of classical physics.
“As a physicist I deal with basic science, in an attempt to understand the fundamental laws of nature based on theory, observations and experiments,” Gershoni said. “I believe that our discovery will advance the field of quantum information processing, and that in the near future we will be able to see genuine applications of quantum technologies in broad use.”
Physicists and technology firms have pursued the idea of producing a quantum computer for about three decades, in hopes of transporting the world of information and computers to entirely different worlds. The idea goes back to physicist Richard Feynman who proposed the idea of quantum computerization in the 1980s. In effect such a machine would process data but in contrast to a classical computer, it would utilize the characteristics of quantum mechanics.
The difference is that whereas in the classical computer the basic unit of information is a bit, a quantum computer uses a quantum bit known as a “qubit.” The difference between the two units is enormous.
“In classical physics, when you transfer a bit of information it’s zero or one, there is a current or there isn’t a current,” Gershoni said. “Quantum physics takes into account the entire area of possibilities. In other words, the bit can be both zero and one at the same time. This possibility is built on a dual description - of both a particle and a wave. Quantum physics doesn’t seek the precise place of the particle in space. In general, the claim is that probability doesn’t describe the particle in nature – it’s nature itself.”
A quantum computer can more quickly calculate what could take the fastest conventional computers millions of years, if not more, to resolve. It can potentially contribute greatly to the fields of medical research, advanced artificial intelligence, securing information and developing codes, “and in effect any field where calculating power is of significance,” Gershoni said.
Billions of dollars are being invested globally in the field of quantum information by giant corporations like IBM, Microsoft and Google and government agencies such as the U.S. National Security Agency.