Self-repairing quantum computers: Error-free and fault-tolerant

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  Quantumrun Foresight
• February 14, 2023

Insight summary

Quantum computing represents a paradigm shift in computer processing. These systems have the potential to solve complex calculations in a matter of minutes that would take classical computers years, sometimes centuries, to accomplish. However, the first step in enabling the full potential of quantum technologies is ensuring they can self-repair their outputs.

Self-repairing quantum computing context

In 2019, the Google Sycamore chip, containing 54 qubits, was able to perform a calculation in 200 seconds which normally would take a classical computer 10,000 years to finish. This achievement was the catalyst of Google's quantum supremacy, receiving worldwide recognition as a major breakthrough in quantum computing. Subsequently, this has spawned further research and advancements within the field.

In 2021, Sycamore took another step forward by demonstrating that it can fix computational errors. However, the process itself introduced new errors afterward. A usual problem in quantum computing is that their calculations' accuracy rates are still lacking compared to classical systems. 

Computers that use bits (binary digits, which are the smallest unit of computer data) with two possible states (0 and 1) to store data come equipped with error correction as a standard feature. When a bit becomes 0 instead of 1 or vice versa, this type of mistake can be caught and corrected.

The challenge in quantum computing is more intricate as each quantum bit, or qubit, exists simultaneously in a state of 0 and 1. If you attempt to measure their value, the data will be lost. A long-standing potential solution has been to group many physical qubits into one “logical qubit” (qubits that are controlled by quantum algorithms). Even though logical qubits have existed before, they weren't employed for error correction.

Disruptive impact

Several research institutions and AI labs have been studying how to make logical qubits that can self-correct. For example, US-based Duke University and Joint Quantum Institute created a logical qubit that functions as a single unit in 2021. By basing it on a quantum error correction code, faults can be more easily detected and corrected. Additionally, the team made the qubit fault-tolerant to contain any negative effects from said errors. This result was the first time a logical qubit was shown to be more reliable than any other required step in its creation.

Using the University of Maryland’s ion-trap system, the team was able to cool up to 32 individual atoms with lasers before suspending them over electrodes on a chip. By manipulating each atom with lasers, they were able to use it as a qubit. The researchers have demonstrated that innovative designs might one-day free quantum computing from its current state of errors. Fault-tolerant logical qubits can work around the flaws in contemporary qubits and could be the backbone of dependable quantum computers for real-world applications.

Without self-correcting or self-repairing quantum computers, it would be impossible to make artificial intelligence (AI) systems that are accurate, transparent, and ethical. These algorithms require large amounts of data and computing power to fulfill their potential, including making autonomous vehicles safe and digital twins that can support Internet of Things (IoT) devices.

Implications of self-repairing quantum computing

Wider implications of investments in self-repairing quantum computing may include: 

• Developing quantum systems that can process higher volumes of data while catching mistakes in real-time.
• Researchers developing autonomous quantum systems that not only can self-repair but self-test.
• Increased funding in quantum research and microchip development to create computers that can process billions of information but require less energy.
• Quantum computers that can reliably support more complex processes, including traffic networks and fully automated factories.
• The full industrial application of quantum computing across all sectors. This scenario will only become possible once companies feel confident enough in the accuracy of quantum computing outputs to guide the decision-making or to operate high-value systems.

Questions to consider

• What are the other potential benefits of stable quantum computers?
• How might such technologies affect your work in the future?