Breaking the “Three Nines”! Ion trap quantum computing reaches new heights

If you compare quantum computing to a ball game, Quantinuum has certainly hit another beautiful shot. In fact, combined with progress this spring on quantum volume, logical quantum bits, and the wiring problem, the team is close to completing a perfect game.

In March, Quantinuum researchers proved the scalability of the QCCD architecture, solving the cabling problem

In April, Quantinuum partnered with Microsoft to demonstrate a breakthrough in reliable logic quantum bits, with a logic circuit error rate 800 times lower than the corresponding physical circuit error rate, and claimed to be “entering a new phase of reliable quantum computing”

On April 16th, Quantinuum announced in a blog post that their Ion Trap Quantum Computer has become the first commercially available quantum computer to achieve 99.914(3)% fidelity for a two-qubit gate.

The scientists refer to this achievement as the “three nines” threshold, meaning that there is a 99.9% probability that the fidelity of a quantum operation or quantum gate will be at least 99.9%.

The company also noted in the article that the quantum volume (QV) of its ion-trap quantum computer has exceeded one million and is growing exponentially, far outpacing its competitors.

Boosting Industry Confidence Toward Fault-Tolerant Quantum Computing

Ilyas Khan, founder and chief product officer at Quantinuum, noted that achieving these benchmarks is critical to building confidence and trust across the quantum computing industry, which is not just an academic study.

“We understand that the entire quantum computing industry and its ecosystem, from vendors to end users, needs three things.” Khan explains, “The first is transparency and consistency regarding timelines and commercial applications.”

“Second is a clear roadmap for development. And thirdly, there needs to be a reliable set of benchmarking standards - everyone needs to understand that the number of quantum bits is just one of many metrics that determine computing power.

At Quantinuum, our work emphasizes certainty. We set strict timelines for ourselves, and we stick to them. We are open to the public about the progress and plans of our work to ensure that every step we take benefits the entire ecosystem.”

Quantum error correction is a core challenge in building reliable, scalable quantum computers, which relies on the underlying hardware achieving a sufficiently high level of fidelity. If the arithmetic error rate of physical quantum bits is too high, error-correcting codes will not reduce but rather amplify the overall error rate, making the system unusable for practical applications.

Quantinuum scientists point out that the industry has been working for decades to achieve 99.9% fidelity for two-qubit gates. This goal is critical: reaching this fidelity threshold is considered a key milestone in the transition from current noise-containing intermediate-scale quantum computers (NISQ) to future fault-tolerant quantum devices.

In a press release, the company states, “Achieving this level of physical fidelity is critical for commercial-scale quantum computers; it is key to the effective implementation of error correction strategies, which in turn are the foundation of any practical quantum computer.”

First realization of 99.9% fidelity for double quantum bit gates

Double-qubit randomized benchmark data from the five gate regions of H1-1 (dashed line) and the average of all five gate regions (solid blue line). Not only do all regions agree with 99.9%, but all regions are greater than 99.9% outside the error bars

This achievement by Quantinuum marks an important step in realizing the full potential of quantum computing. The company's H-Series quantum computers have demonstrated repeatable performance across all quantum bit pairs, distinguishing them from one-off laboratory demonstrations.

Dave Hayes, Quantinuum's senior R&D manager, explained, “Achieving ‘three nines’ in the QCCD architecture means that the system can complete about 1,000 entanglement operations before an error occurs.” He added: “Our quantum computers are approaching the stage where they can perform computational tasks that classical computers cannot. This breakthrough will occur between 'three nines' and 'four nines'. Until this stage is reached, while some tasks are extremely difficult for classical computers (e.g., Google's random circuit sampling problem), the range of problems we can solve will be greatly expanded when we enter this new stage.”

Quantum volume breaks the million mark

Quantum volume (QV) “heavy output probability” (HOP) as a function of temporal circuit index

In March of this year, Quantinuum published a study that specifically emphasized the importance of quantum volume as a comprehensive and difficult to manipulate performance measurement tool, arguing that it is a true reflection of the actual computing power of quantum computers.

This metric takes into account all aspects of a quantum computer's performance, including the number of quantum bits, gate fidelity, and connectivity, solidifying Quantinuum's leadership in the field.

For those looking for technical details, Quantinuum has also published the technical data and hardware specifications for the quantum volume test on GitHub.

The original H1 processor, launched in October 2020, had just 10 quantum bits with a quantum volume of 128 (or 2^7). Over the years, the company has not only improved the quality of the quantum bits, but also doubled the number of quantum bits through a series of incremental upgrades.

Next, Quantinuum will apply all the improvements and lessons learned from the H1 to the next generation H2 processor, which currently supports 32 quantum bits. The company plans to further expand support in the future and increase quantum bit fidelity to a level similar to the H1 processor.

Hayes explains, “At this stage, these machines will be a real tool for pioneering new discoveries - although the areas they can explore are limited at the moment and are likely to be mainly physics simulations or closely related problems.”

“In addition, these high fidelities provide the basis for us to build fault-tolerant machines. With these fidelities, we can start adding more quantum bits without having to boost performance further, and increase the computational power needed to solve really large problems through quantum error correction. This scaling will also become simpler as fidelity increases further (which is why we're not just satisfied with 'three nines'), but it is feasible in principle.”

Objectively, this demonstration is another step towards realizing commercially valuable quantum advantages. While many researchers are still exploring error correction techniques, it should be noted that as the fidelity of raw physical quantum bits improves, the effectiveness and efficiency of error correction will also improve significantly.

Although quantum researchers disagree on whether commercial applications can run on uncorrected NISQ-class machines, the likelihood of this is increasing as the fidelity of raw quantum bits improves. Thus, these advances will contribute to more efficient implementation of error correction on non-error-correcting NISQ machines as well as in error-tolerant machines.

Quantum Pioneer: Technological breakthroughs drive commercial applications

Three years on, Quantinuum has progressed significantly and is climbing to a peak valuation of $5 billion. In January of this year, the company closed a round of equity financing of up to $300 million, bringing the total amount raised since inception to approximately $625 million, far more than any other company in the industry.

Quantinuum continues to realize technological breakthroughs, ensuring its excellence in quantum computing by providing a full-stack solution that integrates high-performance hardware, operating systems and quantum algorithms.

In March 2024, Quantinuum researchers proposed solutions to the Wiring Problem and the Classification Problem.

Quantinuum's approach reduces the traditional complexity of controlling quantum bits by simplifying the control system to use a fixed number of analog signals and a single digital input for each quantum bit, making it more feasible to increase the number of quantum bits, according to the press release. The team also developed a specially designed two-dimensional trap chip that efficiently moves and interacts with quantum bits, overcoming the spatial and operational constraints of traditional linear or toroidal quantum bit arrangements and enhancing the functionality and scalability of quantum computing systems.

Additionally, Quantinuum announced a breakthrough in quantum error correction with Microsoft, demonstrating the ability to create the most reliable logic quantum bits in history. By encoding 30 physical quantum bits into four logical quantum bits on its H2 quantum computer, the team achieved a logical circuit error rate that was lower than the physical circuit error rate, a capability unique to its full-stack quantum computers.

The achievement of these three accomplishments positions Quantinuum as a leader across the industry. The company has demonstrated that it will continue to maintain this leadership position.Quantinuum is the world's leading quantum computing company, and its top-notch scientists and engineers continue to push the technology forward and open up more possibilities for users. Their applied work in areas such as Quantum Chemistry, Quantum Monte Carlo Integration, Quantum Topological Data Analysis, Condensed Matter Physics, High Energy Physics, Quantum Machine Learning, and Natural Language Processing brings new solutions to some of the biggest challenges.

The rapid development of Quantinuum is significant for organizations evaluating quantum technologies and strategies, signifying that quantum computing is not only now available, but is beginning to have a significant impact on commerce. This trend is evident even though fully fledged quantum computers are still years away.

Despite the range of research results achieved, Khan says Quantinuum's journey is not over. He explains, “This year, we removed any doubt about whether our QCCD technology could be scaled up to a quantum computer that solves real-world problems, and our current position in the industry means that our lead has widened.”

Parent company Honeywell has predicted that quantum applications will create a market value of $1 trillion by 2050, by which time Quantinuum will have access to more than half ($550 billion) of the potential market, including areas such as fertilizer production ($200 billion), pharmaceuticals and healthcare ($110 billion), and new materials design ($170 billion).

Khan said, “We look forward to sharing further details of our short, medium and long term roadmap and sharing details of our AI strategy.”