Interface between processor and memory
Similar to classical computers, future quantum computers might be built with different components. Scientists have already built small-scale quantum processors and memories experimentally, and they have used different protocols to encode logical qubits: For example, for quantum processors they use so-called color codes and for quantum memories surface codes. “For the two systems to interact with each other quantum mechanically, we have to connect them,” says PhD student Hendrik Poulsen Nautrup. “We have developed a protocol that allows us to merge quantum systems that are encoded differently.” The scientists suggest to locally modify specific elements of the encoded quantum bits. This process is also called lattice surgery, which is used to couple systems such as quantum processors and memories. Once the systems are temporarily “sewed” together, quantum information can be teleported from the processor to the memory and vice versa. “Similar to a data bus in a conventional computer, scientists can use this technique to connect the components of a quantum computer,” explains Poulsen Nautrup.
This new scheme is another step towards building a universal quantum computer and research for experimental realization is under way. The research was conducted within the framework of the doctoral program Atoms, Light, and Molecules offered at the University of Innsbruck and was funded by the Austrian Science Fund and the Templeton World Charity Foundation.