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Quantum in Context: Pasqal Is the Latest to Publish a Roadmap

Quantum in Context: Pasqal Is the Latest to Publish a Roadmap

The News: The French quantum computing company Pasqal published a roadmap for delivering 10,000 neutral atom qubits in 2026, with an implementation that will support logical qubits with some degree of error detection and correction. Read the details in Pasqal’s press release on its website.

Quantum in Context: Pasqal Is the Latest to Publish a Roadmap

Analyst Take: Following in the footsteps of IBM, IonQ, QuEra, and Infleqtion, Pasqal has issued an aggressive roadmap for delivering many more neutral atom qubits than the company can currently support. It can be challenging to compare roadmaps beyond the numbers because implementations and programming models vary. For example, IBM, IonQ, and Infleqtion use digital qubits and a gate-and-circuit programming model analogous to classical computers, but QuEra and Pasqal now use an analog, or digital-analog hybrid, model that more closely compares to simulating physical processes. Neutral atoms are a good candidate for having individual quantum cores with thousands or tens of thousands of qubits. If Pasqal reaches its milestones, it will represent significant progress for the industry and eventual users.

Neutral Atoms for Quantum Computers

Pasqal, like QuEra, uses rubidium neutral atoms in its quantum computers. Neutral means that the atoms have no net electric charge. They do not repel each other like ions, so they are easier to contain and control. Cesium is another popular choice; each is also used by vendors for atomic clocks and quantum sensors.

Quantum in Context: Pasqal Is the Latest to Publish a Roadmap
Rubidium and Cesium alkali metals in the periodic table of elements (Image Source: Wikimedia Commons)

The atom qubits are moved and controlled by lasers to execute 1- and 2-qubit operations. If you imagine the atoms placed in an array like a checkerboard, 1000 atoms take up less space than the area of a human hair. While this is extremely compact, it also means that the laser control must be very precise. For example, if you aim at one atom but slightly graze another, the second atom’s quantum state will be perturbed, introducing errors.

Pasqal’s challenge is to move from 100 atoms today to 10,000 by the end of 2026 by increasing the size of the array and controlling the atoms with great precision. That is two orders of magnitude in 2 ¾ years, which is why I term it aggressive. In the long run, neutral atom and ion-trap quantum computing vendors will use photonic integrated circuits (PICs) instead of large lasers to reduce their systems’ size, weight, power, and cost, though that may come later than 2026.

Logical Qubits and Error correction for Quantum Computing

The neutral atoms in Pasqal’s quantum computing systems are examples of physical qubits. They hold their values briefly, and we may introduce errors when we perform operations on them. We want to detect and correct any such errors.

Classically, we use error-correcting codes in processors, memory, and storage to perform these repairs. An example of a simple code is the repetition code. Suppose I want to send you a single 0 or 1 bit reliably. I make ten copies of the bit and send you the string of eleven bits. So, if I want you to receive a 1, I send 11111111111. If you receive six or more instances of a bit value in the string, you take that as the value: 11001111101 yields 1. If there is a lot of noise on the channel I use to send the information, we may decide to use more bits.

We cannot do this with quantum computers and the quantum state values in qubits because we cannot copy quantum states. None of the other more efficient classical error correction codes work either.

Researchers have developed special quantum error codes, but the codes have strict requirements on how many errors are introduced by 1- and 2-qubit operations. We also need hundreds of qubits to create a combination that can detect and correct errors in a single quantum value. We call this collection of physical qubits and an error correction code a logical qubit. We have not yet standardized the definition of a logical qubit. I have seen the term used for error detection and not correction. A logical qubit is not perfect; it just has a very low error rate by construction. We must specify this rate if we want to do fair comparisons.

Pasqal’s choice of neutral atoms is good because the company believes it can create many relatively long-lasting physical qubits with low operational error rates. However, these operations are slow compared with superconducting approaches such as IBM’s. The race to build the best quantum computing system is full of tradeoffs.

Key Takeaway: Pasqal’s Technical Quantum Computing Goals Are Doable But the Timeline Is Very Aggressive

The roadmap publishing process has become competitive, with some companies seemingly unwilling to state that they will have fewer qubits with worse specifications than others in the industry. Ultimately, innovation in physics and engineering with a good dose of great software will determine who first delivers a quantum computer that provides Practical Quantum Advantage for the use cases we care about. I am tracking quantum computing company roadmaps and their promised milestones, so time will tell.

Disclosure: The Futurum Group is a research and advisory firm that engages or has engaged in research, analysis, and advisory services with many technology companies, including those mentioned in this article. The author is a former IBM employee and holds an equity position in the company. The author does not hold any equity positions with any other company mentioned in this article.

Analysis and opinions expressed herein are specific to the analyst individually and data and other information that might have been provided for validation, not those of The Futurum Group as a whole.

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Author Information

Dr. Bob Sutor has been a technical leader and executive in the IT industry for over 40 years.Bob’s industry role is to advance quantum and AI technologies by building strong business, partner, technical, and educational ecosystems. The singular goal is to evolve quantum and AI to help solve some of the critical computational problems facing society today. Bob is widely quoted in the press, delivers conference keynotes, and works with industry analysts and investors to accelerate understanding and adoption of quantum technologies.Bob is the Vice President and Practice Lead for Emerging Technologies at The Futurum Group. He helps clients understand sophisticated technologies in order to make the best use of them for success in their organizations and industries. He is also an Adjunct Professor in the Department of Computer Science and Engineering at the University at Buffalo, New York, USA.More than two decades of Bob’s career were spent in IBM Research in New York. During his time there, he worked on or led efforts in symbolic mathematical computation, optimization, AI, blockchain, and quantum computing. He was also an executive on the software side of the IBM business in areas including middleware, software on Linux, mobile, open source, and emerging industry standards. He was the Vice President of Corporate Development and, later, Chief Quantum Advocate, at Infleqtion, a quantum computing and quantum sensing company based in Boulder, Colorado USA.Bob is a theoretical mathematician by training, has a Ph.D. from Princeton University, and an undergraduate degree from Harvard College.

He’s the author of a book about quantum computing called Dancing with Qubits which was published in 2019, with the Second Edition scheduled for release in April, 2024. He is also the author of the 2021 book Dancing with Python, an introduction to Python coding for classical and quantum computing.Areas in which he’s worked: quantum computing, AI, blockchain, mathematics and mathematical software, Linux, open source, standards management, product management and marketing, computer algebra, and web standards.

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