Qubits are the “building blocks” of quantum computers. They are also highly unstable – and that means lots of errors.
Enter Australian Scientists: who are smashing it on every level when it comes to quantum computing advancements. Of course, they have found a “quantum hack” – a way to modify qubit surface codes, improving quantum error correction by up to four hundred per cent.
The research team says the hack means “enormous” efficiency gains in quantum computing technologies.
“As scientists at IBM, Google, Microsoft and universities across the world seek to scale-up quantum technology to make a practical quantum computer, finding ways to do computations within an acceptable error threshold is a big technological problem,” a statement from The University of Sydney reads.
“Qubits are prone to interference from their surrounding environments, leading them to decohere and lose their quantum properties,” The UoS explains, “Allowing for this through error correction is vital to the successful scale-up of quantum technologies.”
The theoretical breakthrough from the team of David Tuckett, Professor Stephen Bartlett and Associate Professor Steven Flammia allows for a 400 per cent gain in the amount of interference noise a quantum computing system can theoretically sustain, while retaining its fidelity.
“This is achieved by tailoring our quantum decoder to match the properties of the noise experienced by the qubits,” said Associate Professor Flammia. “In that sense, we are ‘hacking’ the generally accepted coding for error correction,” Professor Bartlett said.
The research is published this week in the top-tier journal Physical Review Letters. It forms part of Tuckett’s work as a PhD candidate at the University.
At present the rule-of-thumb threshold for fidelity in a qubit architecture is about 1 per cent. This means at least 99 per cent of a system’s qubits need to retain information and coherence for relevant periods of time in order to do any useful computations.
This real-world threshold of 1 percent comes from a theoretical approach where ideal hardware should allow for 10.9 per cent error threshold. The drop in tolerance comes from “noise” in using real-world machines.
Assuming ideal hardware, the work of the Sydney quantum team, which is based at the University of Sydney Nano Institute, has an error correction threshold of up to 43.7 per cent – a fourfold improvement on the current theoretical basis for error correction
This means fewer physical qubits could be required for a single quantum logic gate – or basic quantum circuit – that can perform a useful calculation.
We should be able to use this approach in any quantum system – whether the quibits rely on superconductors, trapped ions, semiconductors, or topological structures (should they need them). Experimental scientists now need to apply this “quantum hack” to real-world systems to see how it flows through using “noisy” hardware.