Quantum computing: What’s the big deal?

Updated 26 May 2020

Google claimed ‘quantum supremacy’ last year with their ‘Sycamore’ superconducting quantum computer. At CSIRO, we refer to quantum supremacy as ‘quantum advantage’. So, what is the quantum advantage and, for that matter, what are quantum technologies? Let us break it down for you.

What is a quantum computer?

Quantum physics explains the behaviour of the world at the smallest scale. Most computers already rely on quantum technologies such as semiconductors and laser optics. But, moving forward, a fully-fledged quantum computer will take our understanding of quantum physics to a whole new level.

Basically, a quantum represents the smallest unit of mass, energy or other physical quantity. Scientists can isolate, control and sense individual quantum particles (like electrons and protons) and their properties. In a quantum computer we use these capabilities to create an entirely new form of computation.

Quantum computers won’t be useful for watching cat videos or posting memes. But they have the potential to solve problems that are impossible on current computing systems. At the moment quantum computers are small and prone to errors. In the future, large-scale accurate quantum computers could help develop new medicines, advance artificial intelligence and engineer energy-efficient batteries. They could also offset the massive amounts of energy consumed by the world’s supercomputers.

What is the quantum advantage?

Quantum advantage is the point where a quantum computer can do something that a normal computer can’t in a reasonable amount of time.

Google claims to have run a computation on their quantum processor in 200 seconds that they suggest would take 10,000 years to simulate on a normal computer. This is an amazing breakthrough for the technology, but it comes with some important caveats:

The computation used to benchmark the performance has no known practical use.

Quantum computing researchers at IBM claim that instead of 10,000 years, the same task could be simulated in 2.5 days on a classical super computer.

How might we use a ‘supreme’ quantum computer?