Quantum annealing

Annealing a metal by heating and cooling
Annealing a metal by heating and cooling

The process called quantum annealing is a hot topic! We’ve posted a preprint which extents recent ideas from an Innsbruck team, for realising such a technology in a powerfully flexible form.

The word ‘annealing’ usually refers to a process where a metal is heated and slowly cooled (see image). But in quantum annealing a system is slowly moved from one cold state (actually, the ground state, which is the coldest possible!) to another, and then all its components (‘spins’) are measured. The purpose? The final state holds valuable information: it encodes the solution to an optimisation problem, perhaps something as prosaic as a perfecting a financial portfolio or routing vehicles for deliveries.

A problem with this interesting idea is that in real devices, the components can’t all link to each other at once; this puts limits on the kind of problems that can be tackled efficiently. A new way around this issue was recently proposed by a team of theorists in Innsbruck. We like the idea, and by thinking about it in the language of stabilisers we’ve spotted a possible simplification that might make the hardware more practical.