Data bus for quantum computer developed

Posted Nov 10, 2017 by Tim Sandle
Quantum physicists have devised a protocol for the transfer of quantum information between differently encoded building blocks of a future quantum computer, including processors and memories.
Photograph of a chip constructed by D-Wave Systems Inc. designed to operate as a 128-qubit supercond...
Photograph of a chip constructed by D-Wave Systems Inc. designed to operate as a 128-qubit superconducting adiabatic quantum optimization processor, mounted in a sample holder.
D-Wave Systems, Inc. (CC BY 3.0)
Steps are moving science and technology towards functioning quantum computers. There are many obstacles, however; not least because quantum world is fragile. In this domain error correction codes are required to protect the information stored in a quantum object from the deteriorating effects of noise.
To overcome this research has shown that the error rate can be reduced by encoding quantum information into several quantum objects instead of one. These logical quantum bits or qubits are more robust against noise. However, a problem remains with transferring information between future quantum computers computers.
In a step forwards, quantum researchers from the University of Innsbruck have come up with a protocol to pass quantum information between differently encoded building blocks, as would be required in a future quantum computer. Researchers can now use this protocol to build a data bus for future quantum computers.
A bus is the communication system that transfers data between components inside a computer, or between computers. The internal data bus connects all the internal components of a computer, such as the CPU and memory, to the motherboard. The data bus is quick and it is independent of the rest of the computer operations.
According to lead researcher Hendrik Poulsen Nautrup: "We have developed a protocol that allows us to merge quantum systems that are encoded differently." This has been achieved by locally modifying specific elements of the encoded quantum bits. This process is called lattice surgery, which is used to couple systems such as quantum processors and memories.
The new development has been published in a paper in the journal Nature Communications. The paper is called "Fault-tolerant interface between quantum memories and quantum processors."