An international team of scientists from Australia, Japan and the United States has created a prototype of a large-scale quantum processor consisting entirely of laser light. The concept of such a processor was developed just over ten years ago, this processor has a scalable architecture that allows you to increase the number of quantum computing nodes consisting of light, almost to infinity.
“Modern quantum processors are large, complex, and expensive devices whose architecture is difficult to scale to,” – the scientists write. “Our approach was initially focused on scaling because the processor, called the group state, is made entirely of light”.
The group state (cluster state) is a large number of quantum components entangled with each other, which allow you to perform quantum calculations, carry out the transfer of information and perform all the necessary basic functions.
“In order for a group state to be used in the real world, it must be both large and have the correct structure of entanglement of elements. For a decade of research in this direction, not a single created group state was operational, having failed in one of two or both cases,” the scientists write. “Our implementation was the first to succeed in every way”.
To create a group state, scientists used special crystals to convert ordinary laser light into a special quantum form called squeezed light. This squeezed light, transmitted through a complex system of mirrors, optical splitters, fiber optic waveguides and other optical components, makes it possible to obtain a two-dimensional group state in the working space, measuring 5 by 1240 nodes. Each node is a separate quantum component (qubit), capable of independently or together with others to process quantum information.
And although the degree of compression of this state, which determines its quality, is still small for solving practical computational problems, everything indicates that the principles chosen by scientists are workable and in the near future they will be able to obtain the required degree of compression of the group state.
“In our work, we created a large-scale group state, the structure of which already allows us to perform some quantum calculations,“ the scientists write, “All this is the very first demonstration that the ideas laid down are workable, creating a “light“ quantum processor is feasible, and the architecture created is scalable to any level of complexity”.