Image: An artists depiction of a network of small quantum systems with the overall topology of a torus. (c) Karl Nyman 2013.
In the last couple of years there has been rapid progress toward realising quantum technologies. The qubits (quantum bits) upon which such technologies are founded have been improving, with longer lifetimes and better levels of control. But one thing remains elusive: scaling the few-qubit prototypes in the laboratory up to the many-qubit systems that can tackle real world tasks.
In response to this challenge, a number of researchers worldwide have been studying the possibility of a network approach: instead of trying to create a single 'monolithic' quantum cpu with many thousands or millions of qubits, instead focus on making small systems with only a few qubits, and wire them up to form the full scale machine. It sounds like an attractive solution, but there has been a problem: the 'wires' that have been demonstrated so far are very error prone, and consequently the operations within each little unit must be almost perfect in order to counteract the errors on the links. Or so it seemed, but now a joint Oxford-Singapore team writing in the journal Nature Communications have described a method by which one can have the best of both worlds: the scalable flexibility of a 'noisy network', yet without any impractical demands on the precision of qubit control. The team, led by Simon Benjamin of Oxford's Quantum and Nanotechnology Theory group (QuNaT), explained their work to Oxford science blogger Pete Wilton.