Logical qubits start outperforming physical qubits
Quantinuum closes in on breakeven point in quantum error correction
Broomfield, Colorado, August 4th, 2022 — Quantinuum researchers have hit a significant milestone by entangling logical qubits in a fault-tolerant circuit using real-time quantum error correction. The research, published in a new scientific paper that was released on August 3rd, is the first experimental comparison study of different quantum error correction codes in similar environments and presents a collection of several different experiments. These experiments include:
- The first demonstration of entangling gates between two logical qubits done in a fully fault-tolerant manner using real-time error correction
- The first demonstration of a logical entangling circuit that has higher fidelity than the corresponding physical circuit.
This milestone achievement is important because it marks the first time that logical qubits have been shown to outperform physical qubits — a critical step towards fault-tolerant quantum computers.
“Quantinuum’s trapped-ion quantum computing roadmap is designed around continuous upgrades, enabled our flexible architecture and our precision control capabilities. This combination provides for outstanding, first-of-its-kind achievements that help accelerate the entire industry,” said Tony Uttley, President and COO of Quantinuum.
David Hayes, a Theory and Architecture Technical Manager at Quantinuum and co-author of the new research paper, said the research moves quantum computing closer to the point where encoded circuits outperform more primitive operations.
“People have worked with error corrected qubits before, but they haven't reached this sort of special point where the encoded operation is working better than the primitive operation,” Hayes said. “The other thing that's new here is that in other experiments we're doing the error correction while we're doing the operations. An important next step for us is to get the error rate induced by the error correction itself down further."
The findings are described in the new research paper, “Implementing Fault-tolerant Entangling Gates on the Five-Qubit code and the Color Code”. The paper was recently published on the arXiv. Scientists used both the H1-1 and the H1-2 quantum computers, Powered by Honeywell, to compare the Five-Qubit error code and the Distance Three Color Code in these tests.
Quantum researchers are in the early days of experimental quantum error correction with a multitude of codes to test. Quantinuum researchers can explore a wider range of quantum error codes, compared to other quantum hardware designs, due to the architecture of the machine.
The System Model H1 uses a trapped-ion design and a quantum charged coupled device architecture (QCCD). Along with the inherent flexibility of this design, another strength is all-to-all connectivity. All the qubits are connected to each other which makes it easy to move information through chains of ions without creating multiple errors along the way.
“Instead of having to build a new machine every time we want to try a new code, we can just program the machine to run a different code, make the measurements and weigh the different pros and cons,” Hayes said.
Advancing quantum error correction
All forms of technology need error correction including servers in data centers and space probes sending transmissions back to Earth. For Quantinuum and other companies in the quantum computing sector, quantum error correction is one of the most important pillars of progress. Errors prevent quantum computers from producing reliable results before they are overwhelmed. Quantinuum’s researchers are working toward the milestone of fault tolerance, meaning the errors can be suppressed to arbitrarily low levels.
Natalie Brown, another co-author of the paper and an Advanced Physicist at Quantinuum, said that most classical error correction principles fail with quantum computers because of the basic nature of quantum mechanics.
“It becomes very difficult to suppress noise to very small levels, and that becomes a problem in quantum computing,” she said. “The most promising candidate was this quantum error correction, where we take the physical qubits, make a logical qubit.”
Logical qubits are groups of physical qubits working together to perform a computation. For each physical qubit used in a computation, other ancillary qubits perform a range of tasks such as spotting and correcting errors as they occur.
Ciaran Ryan-Anderson, a Senior Advanced Physicist at Quantinuum and also a co-author of the new paper, said the newest research paper builds on research performed in 2021 and published in Physical Review X. That work explained how researchers at Honeywell Quantum Solutions applied multiple rounds of quantum error correction to a single logical qubit.
“One of the first really important things to demonstrate was these repeated rounds of quantum error correction cycles,” he said.
That is one of several milestones on Ryan-Anderson’s quantum error correction checklist:
- Conduct repeated rounds of fault tolerant quantum error correction
- Feed forward and conditionally apply syndrome extraction
- Enable real-time determination of correction for a quantum error correction code
- Demonstrate general algorithmic real-time decoding
- Scale up quantum error correction with two logical qubits
- Hit the breakeven point when logical quantum computing starts to outperform physical quantum computing
“Quantinuum has achieved some of the milestones required to accomplish this now,” Ryan-Anderson said.
Five-Qubit Code vs. Color Code
Building upon the 2021 research involving one logical qubit, the newest research illustrates the Quantinuum team’s progress with quantum error correction and two logical qubits. The team tested two error codes familiar to quantum experts: the Five-Qubit Code and the Color Code. The Five-Qubit Code does not allow for a fault tolerant transversal gate using only two logical qubits. Researchers used “pieceable” fault tolerance to decompose an initially non-fault tolerant logical gate operation into pieces that are individually fault-tolerant. The Color Code, however, does allow the use of a transversal CNOT gate which is naturally fault-tolerant.
How the experiment worked
H1-2 can use up to 12 qubits and H1-1 can use up to 20. The Five-Qubit Code tested on H1-2 while the Color Code tested on H1-1. Both computers use the same surface electrode ion trap to control ytterbium ions as qubits. Ion transport to isolated gate zones with focused laser beams provides low crosstalk gate and mid-circuit measurement operations.
The researchers ran five experiments with different combinations of circuit elements to test the Five-Qubit Code and to understand the impact of fault tolerant design and circuit depth. The team found that the extra circuitry designed to increase fault tolerance had a negative impact on the overall fidelity of the logical operation, due to the large number of CNOT operations required.
The Color Code showed much better results due in part to the ability to use a transversal CNOT gate. The team ran seven experiments to investigate the fault tolerant potential of these codes. With the Color Code, the researchers found that the State Preparation and Measurement circuits benefitted from the addition of fault tolerant circuitry with a significant reduction of error rates: 99.94% for the logical qubits compared to 99.68% for the physical qubits. This was the only additional circuitry required to make the circuit fault tolerant from end-to-end, since the logical CNOT is transversal and naturally fault tolerant.
The researchers concluded that the “relatively economical fault tolerant circuitry of the Color Code will provide a better platform for computation than the qubit efficient five-qubit code.” Also, the researchers found that the Five-Qubit Code would be useful only in systems with far lower physical error rates than quantum computers have at this point in time.
Hayes said the team’s next step will be to surpass the breakeven point and provide proof of the work. “We are getting evidence that we're really darn close to that point, but there's a lot of work that needs to be done to actually prove it,” he said. “Just getting right there is not good enough, you have to actually get past it.”
A new classical+quantum connection
Another advance from this experiment is a new classical processor with enhanced capabilities which will be essential to scalable algorithmic decoders. The data from the classical functions were used to dictate the control flow and operations executed in the quantum program.
The decoders used in these experiments were partially written in Rust and compiled to WebAssembly (Wasm). The choice of Wasm provides an efficient, safe, and portable classical language to have functions that are callable from quantum programs.
The decoder implemented in Rust uses many high-level program constructs. The support for these features means that various scalable algorithmic decoders can be ergonomically implemented in various high-level languages that compile to Wasm (such as Rust, C, and C++) and called from quantum programs.
“It was pretty enabling for this particular experiment, and it'll be even more important for future experiments as these things get more and more complicated,” Hayes said.
Another advantage of the trapped ion architecture is the ability to do real-time decision making during the execution of the quantum circuit thanks to long coherence times and the ability to do mid-circuit measurement and reset qubits as needed.
“Our systems have very long coherence times which is super advantageous when integrating in the classical compute real-time decision making,” Hayes said.
The Honeywell Trademark is used under license from Honeywell International Inc. Honeywell International Inc. makes no representations or warranties with respect to this product. This product is produced by Quantinuum.
About Quantinuum
Quantinuum, the world’s largest integrated quantum company, pioneers powerful quantum computers and advanced software solutions. Quantinuum’s technology drives breakthroughs in materials discovery, cybersecurity, and next-gen quantum AI. With over 500 employees, including 370+ scientists and engineers, Quantinuum leads the quantum computing revolution across continents.
Doha, Qatar, May 20th, 2025 — Invest Qatar, the Investment Promotion Agency of Qatar, has inked a strategic agreement with Quantinuum, the world leader in quantum computing and developer of the world’s highest-performing quantum computer. The partnership aims to strengthen Qatar’s quantum computing ecosystem by supporting Quantinuum’s recently announced expansion into the region, which was highlighted last week by the President of the United States during his historic state visit to Qatar.
Through this partnership, Invest Qatar will provide tailored support services to Quantinuum, including access to key stakeholders, sector-specific insights and opportunities for collaboration with local innovation and research institutions. Invest Qatar will also promote initiatives that drive quantum computing adoption and raise awareness of Quantinuum’s contributions to Qatar’s tech landscape.Through this partnership, Invest Qatar will support Quantinuum’s expansion into the country to apply quantum technologies for the benefit of key sectors in Qatar, while enhancing local research and development (R&D) capabilities, to create high-skilled jobs and train the next generation quantum workforce in Qatar. This includes facilitating connections with key stakeholders, enabling collaboration in R&D, and aligning with national initiatives aimed at advancing quantum technologies.
As part of the agreement, Quantinuum will play a central role in advancing Qatar’s quantum capabilities by launching a range of targeted initiatives, including knowledge-sharing platforms, educational seminars and technical workshops delivered by Quantinuum’s global experts. The partnership also envisions launching joint research projects with Qatari academic and research institutions, exploring opportunities for local integration of quantum technologies and facilitating access to Quantinuum’s cutting-edge quantum computing infrastructure. Additionally, internship opportunities will be offered to students from Qatar-based universities, providing direct experience in real-world quantum computing applications.
Commenting on the partnership, Sheikh Ali Alwaleed Al-Thani, CEO, Invest Qatar, said: “This partnership with Quantinuum reflects our continued commitment to positioning Qatar at the forefront of next-generation technologies. By combining global expertise with local ambition, we aim to cultivate a thriving quantum ecosystem that drives innovation, supports economic diversification and empowers future talent. We are pleased to work with Quantinuum to unlock the transformative potential of quantum computing for Qatar and the wider region.”
Dr. Rajeeb Hazra, President & CEO, Quantinuum, said: “Launching our presence in Qatar opens an exciting new chapter in a region ready to lead in quantum computing. Building on our recently announced expansion into the country through our joint venture with Al Rabban Capital, and our ongoing partnership with Hamad Bin Khalifa University, this collaboration with Invest Qatar reinforces our commitment to the growth of Qatar’s quantum computing ecosystem. As part of the deepening strategic ties between the U.S. and Qatar, we’re enabling direct access to our world-leading quantum hardware and software, creating value for academia and industry in Qatar while training the next generation of quantum developers and researchers to strengthen the region’s position as a global hub for advanced technologies.”
About Invest Qatar
The Investment Promotion Agency Qatar (Invest Qatar) is responsible for overseeing investment promotion activities, aimed at attracting foreign direct investment to Qatar. Established in 2019, Invest Qatar’s mission is to strengthen Qatar’s position as an ideal investment destination, while facilitating investments that foster economic diversification and development.
As the gateway to investment solutions, Invest Qatar connects investors to an integrated ecosystem of business and licensing platforms. The Agency partners with investors throughout their journey, from exploration and setup to expansion, ensuring their long-term growth by providing comprehensive insights into Qatar’s business landscape, sector-specific market knowledge and tailored investment facilitation.
For more information, please visit www.invest.qa
@InvestQatar | #InvestQatar
About Quantinuum
Quantinuum is the world leader in quantum computing. The company’s quantum systems deliver the highest performance across all industry benchmarks. Quantinuum’s over 550 employees, including 370+ scientists and engineers, across the US, UK, Germany, and Japan, are driving the quantum computing revolution.
For more information, please visit www.quantinuum.com
Doha, Qatar, May 14th, 2025 — Quantinuum, the world leader in quantum computing, is establishing a Qatari-incorporated Joint Venture with Al Rabban Capital, a division of Al Rabban Holding Company, one of Qatar’s most prominent companies. The Joint Venture will accelerate quantum computing adoption in Qatar and the region, strategically positioning the U.S. and Qatar as global leaders in the quantum revolution. This first of its kind quantum technology partnership was highlighted by the President of the United States during his historic state visit to Qatar.
The Joint Venture has three core objectives: enabling access to Quantinuum’s world-leading quantum technologies in the region; co-developing quantum computing applications tailored to regional needs in areas such as New Energy, Materials Discovery, Precision Medicine, Genomics, and Financial Services, with new opportunities emerging in the era of Generative Quantum AI (GenQAI); and, training the next generation of quantum computing developers in Qatar and the region.
Quantinuum is steadily expanding its global presence to meet the growing international demand for its technology and applications. The company’s expansion into the Gulf region, starting with Qatar, follows its successful growth across the U.S., U.K., Europe and Indo-Pacific. This Joint Venture reflects a shared commitment by the U.S. and Qatar to strengthen strategic ties, spur bilateral investment in future-defining industries, and foster technological leadership and shared prosperity.
Quantinuum’s Joint Venture with Al Rabban Capital builds on its partnership announced last year with Hamad Bin Khalifa University and the Qatar Center for Quantum Computing (QC2), Qatar’s premier quantum research hub.
“This is a defining moment in Qatar’s ambition to become a regional hub for advanced technologies like quantum computing,” said Abdulaziz Khalid Al Rabban, Chairman, Al Rabban Capital. “We're partnering with Quantinuum to deliver world-class quantum solutions, driving economic growth in Qatar and the region.”
“This Joint Venture demonstrates our shared vision to lead in transformative technologies,” said Dr. Rajeeb Hazra, President & CEO of Quantinuum. “Together with Al Rabban Capital, we’re accelerating the commercial adoption of quantum computing in Qatar and the region whilst serving U.S. and Qatari strategic interests.”
About Quantinuum
Quantinuum is the world leader in quantum computing. The company’s quantum systems deliver the highest performance across key industry benchmarks. Quantinuum’s over 550 employees, including 370+ scientists and engineers, across the US, UK, Germany, and Japan, are driving the quantum computing revolution.
For more information, please visit: https://www.quantinuum.com
About Al Rabban Capital
Al Rabban Capital (ARC) is a Qatari investment and advisory firm driving business growth across Qatar and the GCC. ARC enable market entry and expansion through joint ventures, strategic partnerships, and deep local insight. ARC supports both public and private sector initiatives with tailored, end-to-end solutions. Beyond capital, ARC provide strategic guidance, governance, and access to a robust regional network. ARC’s focus includes AI, quantum tech, healthcare, and sustainability, with a commitment to impactful growth.
For more information, please visit: https://www.alrabbancapital.com
Broomfield, CO, April 3rd, 2025 — Quantinuum, the industry leader in quantum computing with the world’s most powerful quantum computer, has been selected by the Defense Advanced Research Projects Agency (DARPA), a research and development agency of the United States Department of Defense, to participate in the first stage of the agency’s Quantum Benchmarking Initiative (QBI).
QBI aims to assess the feasibility of building an industrially useful quantum computer by 2033. Successful QBI performers will advance through stages A, B, and C; Stage A requires performers to describe their utility-scale quantum computer with a path to near-term realization, where utility-scale means the computational value exceeds costs.
As validated in a recent independent benchmarking study by a group of institutions at the forefront of quantum computing research, Quantinuum’s quantum systems are the highest performing in the industry. Last year, Quantinuum published its development roadmap, outlining a path to a universal, fully-fault tolerant quantum computer by 2029. Beyond this public roadmap, Quantinuum plans to scale to even larger machines in the early part of the 2030s, aligning with the objectives of QBI.
“We are honored to collaborate with DARPA and look forward to working closely with their test and evaluation team as they assess our roadmap and technological approach,” said Dr. Rajeeb Hazra, President and CEO of Quantinuum. “With our roadmap firmly on track, we are confident in our ability to deliver on DARPA’s objectives for QBI.”
Microsoft and NVIDIA will take part in Quantinuum’s Stage A effort, building on their long-standing collaborations with Quantinuum in advancing commercially scalable quantum computing.
About Quantinuum
Quantinuum is the world leader in quantum computing. The company’s quantum systems deliver the highest performance across all industry benchmarks. Quantinuum’s over 550 employees, including 370+ scientists and engineers, across the US, UK, Germany, and Japan, are driving the quantum computing revolution.