What Faults can Quantum Computing Tolerate?

June 8, 2023

Experts suggest that quantum computers could unlock the answers to some complex problems in areas like chemistry, cybersecurity and medicine. But unfortunately, some of the building blocks of quantum computing are prone to error. Recent advances in what is called fault-tolerant quantum computing, which enables a computer to handle and fix mistakes, may be part of the solution. Understanding the progression from regular computers to quantum computing and now fault-tolerant quantum computing can seem daunting, so we’re breaking it down for you.

Bits power regular computers. The basic component of a regular computer is like a light switch that can be turned on or off, which we call a “one” or “zero”. These switches are called bits. One bit isn’t very powerful. But when you have millions of bits working really fast – completing one thing after another and another – they can do cool things like run video games or help you make posts on social media.

Qubits power quantum computers. Quantum computers use a “special” switch called a qubit, which has a unique characteristic. Not only can qubits be a “one” or a “zero”, they can be both at the same time. Think of it like a coin – on one side is heads and the other is tails. As long as that coin is spinning in the air, it is both heads and tails.

Quantum computers are super powerful and can do many things at once. As such, quantum computers enable big leaps in computer technology and help solve tough problems around the world.

All computers can generate faults. Regular computers can sometimes switch bits from “one” to “zero.” Quantum computer qubits are really sensitive to their surroundings, and things like electricity, magnets, light or even other qubits can mess up their calculations. These barriers are called faults.

But computers can become fault-tolerant. Regular computers make three copies of the same data and constantly check that data for mistakes. If one copy disagrees with the other two, the computer fixes it.

“We use a trick called redundancy for error correction,” IEEE Member Euclides Chuma explains. “We store the same information on multiple bits. This is called encoding. Then we look for anything that’s not a ‘zero’ or a ‘one’ and fix it.”

And fault-tolerant quantum computers are in development. Qubits can’t be easily copied when they’re in their quantum state, and they can make errors unique to quantum computers. As the number of qubits connected together increases, so too does the difficulty of correcting errors.

Despite this, major players in the field are actively trying to enhance quantum computing. One of the strategies involves dedicating a group of qubits to correct errors in another group of qubits.

“One of the solutions is to develop fault-tolerant quantum computers using superconducting circuits as qubits because this hardware is scalable to thousands of physical qubits,” Chuma said.

However, as of now, quantum computers haven’t surpassed regular computers in performance.

By using these methods, we are moving closer to achieving a more reliable, fault-tolerant quantum computing system – and the implications of that could change the world. For example, a faultless 200 qubit computer could potentially identify chemical catalysts to drastically improve fertilizer production, which would significantly impact global energy consumption and climate change.

Learn more: Quantum computing remains a fast-changing field. The IEEE Standards Association has developed several standards to help researchers define, measure and benchmark quantum. Check them out. Or take a look at IEEE Quantum, which is loaded with approachable videos and articles explaining the intricacies of quantum computers.