Universal quantum computers are still somewhere around a decade or two away from being developed, but they will be significant when they arrive. Important new problems will be solved, but new problems will also be created. Much of the cryptography that the world replies upon today will be rendered ineffective (and will need to be replaced) when faced against quantum computers… For example, the asymmetric RSA regularly used to protect online banking will need to be phased out due to what quantum computers will do to today’s asymmetric ciphers. The symmetric cipher AES-256 will have its strength cut in half when faced against a quantum computer, downgrading it to an adequate but less strong AES-128. This is of course only one example.
A team at the University of Sydney and Microsoft, in collaboration with Stanford University in the US, has miniaturised a component that is essential for the scale-up of quantum computing. The work constitutes the first practical application of a new phase of matter, first discovered in 2006, the so-called topological insulators.
Beyond the familiar phases of matter — solid, liquid, or gas — topological insulators are materials that operate as insulators in the bulk of their structures but have surfaces that act as conductors. Manipulation of these materials provide a pathway to construct the circuitry needed for the interaction between quantum and classical systems, vital for building a practical quantum computer.
Theoretical work underpinning the discovery of this new phase of matter was awarded the 2016 Nobel Prize in Physics.