Some tasks that are impossible even with the world’s most powerful supercomputer can be performed by quantum computers. Quantum computing is expected to be used in the future to model material systems, manipulate quantum chemistry, and improve complex operations, with potential applications in medicine and finance. However, flexible hardware is necessary to fulfill that promise. Researchers need to find a better way to connect quantum information, which is the amount of information separated by a computer chip, when building a large quantum computer. The methods used to process electronic information do not directly translate to quantum devices, because quantum computers are very different from classical computers. One requirement, however, is clear: the data must be sent and received, either through a joint or classical connection. MIT researchers have created a computing center that will allow high-performance processors to communicate with reliability and scalability. The first step, a rigorous, user-defined determination of which photons carry information, was presented by MIT researchers in a paper recently published in Nature Physics. More than 96% of the time, their method makes it clear that the quantum information is moving in the right direction.
A larger network of interconnected quantum processors, despite their physical separation from the computer chip, can be created by connecting many types of modules together. According to Bharath Kannan, Ph.D. ’22, the leader of the research paper explains the process, “Quantum interconnects are a crucial step for the implementation of modules of large machines built from individual elements rather than small ones.”
Kannan adds, “A modular architecture for quantum processors will make it possible to communicate between small subsystems, and this could be an easy way to make a large number of different processes compared to power.
The article was written by Kannan and lead author Aziza Almanakly, an MIT graduate student studying electrical engineering and computer science in the Engineering Quantum Systems group at the Research Laboratory of Electronics (RLE). William D Oliver, director of the RLE group, director of the Center for Quantum Engineering, professor of electrical engineering, computer science, and physics, and MIT Lincoln Laboratory Fellow, is the lead author.
Quantum Information Processing Classical computers perform a variety of functions, including memory, computing, and other functions. Interconnects, which are the wires that carry electrons in a computer processor, are used to transfer electronic information between these components. Electronic information is encoded and stored as bits, which have a value of 1 or 0. However, quantum information is more complex. Quantum information can also be both 0 and 1 at the same time – what is known as superposition – instead of only having a value of 0 or 1. A photon, which is a light source, can also carry quantum information. Quantum information is indestructible, and cannot be transmitted using standard protocols because of this added complexity. Photons travel through special couplings called waveguides in quantum networks to connect to structural nodes. The waveguide can be unidirectional, which only moves photons left or right, or bidirectional. Since it is easy to determine the direction of travel of photons, waveguides are used in many industries today. However, since each waveguide moves photons in one direction, scaling this process becomes more difficult as quantum networks grow. In addition, communication errors are introduced when redundant waveguides are used to add direction to the waveguide.
“If we have a wave path that can support left and right propagation and a way to select direction and inclination, we can eliminate these losses. “We demonstrated this ‘directional transfer,’ which is the first step in two-way communication with high reliability,” says Kannan.
Multiple processing modules can be configured in one router due to their architecture. According to him, the fact that one module can work as a transmitter and a receiver is a significant part of the design of the structure. In addition, two modules can send and capture photons in the same waveguide. “There is only one physical link and it can take any number of modules in its path. We are currently working on bringing the photons down to the second module to reflect the direction of the photons from one module,” Almanakly adds.