VQAs for Today's Quantum Computing Hardware

Who has the best quantum processor today? Ask the physics community quietly and many will say: Quantinuum 𝗡𝗼𝘁 IBM Quantum. 𝗡𝗼𝘁 Google. 𝗡𝗼𝘁 IonQ. It’s easy to get caught up in roadmaps, qubit counts or quantum advantage headlines. But the real turning point for the field currently isn’t about scale. It's about fault tolerance - detecting and correcting quantum errors faster than they accumulate. Through that lens, Quantinuum’s H-Series trapped-ion system stands apart. Here’s why: • 𝗥𝗲𝗰𝗼𝗿𝗱-𝗛𝗶𝗴𝗵 𝗚𝗮𝘁𝗲 𝗙𝗶𝗱𝗲𝗹𝗶𝘁𝗶𝗲𝘀: The H-Series delivered a sustained >99.9% two-qubit gate fidelity and >99.99% single-qubit gate fidelity. This is the quality baseline to ensure any QEC code has a chance to work.    • 𝗟𝗼𝗴𝗶𝗰𝗮𝗹 𝗕𝗿𝗲𝗮𝗸-𝗘𝘃𝗲𝗻: They've repeatedly demonstrated logical qubits that are more reliable than the physical hardware they're built from—the first milestone for practical quantum computing.    • 𝗨𝗻𝗶𝘃𝗲𝗿𝘀𝗮𝗹 𝗚𝗮𝘁𝗲 𝗢𝗽𝗲𝗿𝗮𝘁𝗶𝗼𝗻𝘀: Achieved logical gate fidelity an order of magnitude better than physical fidelity on 𝗻𝗼𝗻-𝗖𝗹𝗶𝗳𝗳𝗼𝗿𝗱 𝗴𝗮𝘁𝗲𝘀, which are the hardest operations to perform fault-tolerantly and essential for universal quantum computing.    • 𝗔𝗿𝗰𝗵𝗶𝘁𝗲𝗰𝘁𝘂𝗿𝗮𝗹 𝗔𝗱𝘃𝗮𝗻𝘁𝗮𝗴𝗲: All-to-All Connectivity. The Quantum Charge-Coupled Device (QCCD) system uses ion shuttling to provide full all-to-all qubit connectivity.    • 𝗧𝗵𝗲 𝗤𝗘𝗖 𝗧𝗲𝘀𝘁𝗯𝗲𝗱: This architecture allows them to deploy a diverse range of QEC codes (Steane, Carbon, Tesseract) and test protocols like Single-Shot QEC and Fault-Tolerant Teleportation. It is literally built to explore and accelerate the FTQC roadmap.

Logical qubits announcements are flying these days. Just last week: - IBM Quantum touted an experiment with "140 logical qubits": https://lnkd.in/eNYj7vZC - Quantinuum introduced their Helios computer with up to "94 logical qubits": https://lnkd.in/eEh2BuFQ So, is this it? Are we now in the logical qubit era? Well... we're entering it, but we're not quite there yet. If we go back to the basics, to be called a "quantum computer", a machine must meet DiVincenzo's criteria (https://lnkd.in/e5ETewiB): 1. A scalable physical system with well-characterized qubit 2. The ability to initialize the state of the qubits to a simple fiducial state 3. Long relevant Quantum coherence times 4. A "universal" set of quantum gates 5. A qubit-specific measurement capability Current logical qubit experiments demonstrate 1, 2 and 5. 3 is debatable, since "long" is ill-defined, but some experiments achieve better-than-physical performance, so let's consider we have it too. The real problem lies in 4: most of today's "logical qubits" are either quantum memories (i.e. they can preserve information but not manipulate it), or they feature some gates but not a universal set. This is not a small detail: if you cannot run a specific type of gates (non-Clifford ones) on your logical qubits, then you are left with circuits that can be classically simulated with just a polynomial overhead. In other words: without non-Clifford gates, quantum computing's exponential speedup is gone, and so is any hope of practical advantage. Now, I do agree with Jay Gambetta when he says "the only thing that matters is a quantum computer that runs a quantum circuit with a number of operations on a number of qubits" (in a discussion with Michaela Eichinger, PhD at https://lnkd.in/edJgWda4 ). But I would add: this needs to be true for any operation (or gate) one might want to run. Being able to run millions of Clifford gates is nice but insufficient. Of course, Jay and other industry leaders know this, and research teams are hard at work implementing logical non-Clifford gates. Some results have even already been published, for example here by Quantinuum: https://lnkd.in/esXuxhjj So, next time you see a large number of logical qubits being announced, don't stop at this figure: - Ask if there is a universal gate set - Ask how low error rates are - Oh, and ask how fast logical gates are With this additional information, you'll have a clearer understanding of the progress being made!

PsiQuantum Achieves Breakthrough in Mass-Producing Light-Powered Quantum Chips American quantum computing startup PsiQuantum has announced a major breakthrough in manufacturing scalable photonic quantum chips, marking a significant step toward making practical quantum computing a reality. The company, which emerged from stealth mode in 2021, has been working on a light-powered (photonic) quantum computing approach, which was previously considered impractical due to hardware limitations. Why Photonic Quantum Computing? • Photonic quantum computers encode data in individual particles of light (photons), rather than in superconducting circuits like many other quantum systems. • This approach has key advantages: • Low noise compared to superconducting qubits. • High-speed operation due to the natural speed of light. • Seamless integration with fiber-optic networks, which could make quantum internet feasible. • However, the challenge has always been scaling up, as photons are difficult to control, detect, and stabilize in large-scale computations. PsiQuantum’s Breakthrough • In a paper published in Nature, the company unveiled a manufacturing process that enables large-scale production of photonic quantum chips. • The new hardware design solves key engineering problems, making it possible to reliably manipulate and measure photons at scale. • Unlike previous photonic quantum systems, which struggled with extreme hardware demands, PsiQuantum’s solution reduces errors and improves stability in complex computations. Implications for the Future of Quantum Computing • Scalability Achieved – This breakthrough could allow for mass production of quantum chips, removing a key bottleneck in commercial quantum computing development. • Quantum Networking Potential – With natural fiber-optic compatibility, photonic quantum computers could lead to highly secure quantum communications networks. • New Industrial Applications – The technology may soon be applied to optimization problems, cryptography, and materials science, revolutionizing industries that require complex simulations. The Bigger Picture PsiQuantum’s ability to mass-produce photonic quantum chips puts light-powered quantum computing in direct competition with other approaches, such as superconducting and trapped-ion quantum systems. If successful, it could make quantum computing more accessible, scalable, and commercially viable—a leap forward in the race to achieve practical quantum supremacy.

Today marks a historic milestone in quantum computing, as Microsoft and Quantinuum demonstrate the most reliable logical qubits on record. This breakthrough, with a logical error rate 800x better than the physical error rate, signifies a giant leap from the noisy intermediate-scale quantum (NISQ) level (Level 1 – Foundational) to Level 2 – Resilient quantum computing.   This progress is significant as logical qubits are only useful when they have a better error rate than physical qubits themselves. The number of physical qubits is a misleading metric; it’s not how many qubits, it’s how good they are and how resilient the quantum system is to errors.   Using the logical qubits we created, we were able to successfully perform multiple active syndrome extractions, which is when errors are diagnosed and corrected without destroying the logical qubits. Active syndrome extraction helps quantum computers stay reliable even when operations are imperfect.   With the promise of a hybrid supercomputing system powered by these reliable logical qubits, we’re paving the way for scientific and commercial breakthroughs that were once deemed impossible.  This achievement is a testament to the power of collaboration and the collective advancement of quantum hardware and software.   You can learn more from my post on the Official Microsoft Blog https://lnkd.in/gnDfcUV6 and the companion technical post on the Azure Quantum blog by Dennis Tom and Krysta Svore: https://lnkd.in/gMRVPG3s. #quantum #quantumcomputing #azurequantum

🚀 Microsoft Azure Quantum and Quantinuum announced today a new milestone in the race to practical quantum computing. Some time ago vendors changed direction from having more qubits to having better qubits. As with many things in live, useful quantum computers are a matter of quality rather than quantity when it comes to qubits. Having high quality qubits and the ability to manipulate them with low error rates is a requirement to create any useful quantum circuit, the equivalent to programs in classical computers. In April both partners announced having set up 4 logical qubits (=high quality qubits) from the combination of 30 physical qubits on a Quantinuum H-series machine. (https://lnkd.in/ePp5MC7t) Now they claim having achieved 12 logical qubits on a 56-qubit Quantinuum H2. All 12 logical qubits were entangled in a GHZ state with a circuit error rate of 0.0011. Scaling to error rates in the order of 10^-3 is great news. Practical quantum computers able to address the complex problems waiting for them will require much more than that, but we are on the way. https://lnkd.in/e6e6v8Tk

EeroQ researchers published new findings in Physical Review X about controlling individual electrons at temperatures above 1 Kelvin. Here's what they accomplished: Current quantum computers operate near 10 millikelvin. EeroQ demonstrated electron control at temperatures 100 times higher. Their approach uses electrons floating on superfluid helium, integrated with standard superconducting circuits. Why this matters for quantum computing: → Reduces extreme cooling requirements   → Uses existing quantum hardware infrastructure   → Creates a cleaner environment for qubit operations   → May help with scaling challenges Johannes Pollanen, EeroQ's cofounder, noted this "reduces a key barrier to scalable quantum computing." The company has been developing this electron-on-helium technology since 2017. The work validates theoretical predictions about using helium as a platform for quantum operations. The research addresses a practical problem: current quantum systems require expensive, complex cooling to near absolute zero temperatures. For those working in quantum computing: What cooling challenges do you face in your systems? ♻️ Repost to help people in your network. And follow me for more posts like this.

Big news in quantum computing today. Harvard University, Massachusetts Institute of Technology and QuEra Computing Inc. just demonstrated the first scalable quantum system with full end-to-end error correction, integrating 448 physical qubits into stable logical qubits operating below the error threshold. This is the barrier that has held the entire field back — and they just showed a path through it. The breakthrough brings together all the essential building blocks in a single architecture: entanglement, logical operations, quantum teleportation, entropy removal, and error correction working together. It’s the first credible route toward scaling to thousands of logical qubits and, eventually, real-world quantum machines. This shifts timelines. It accelerates the urgency around post-quantum security, advanced simulation, optimization, and financial applications. And it will move investment, research, and strategy across the entire tech landscape. One month ago I had the chance to visit the IBM Thomas J. Watson Research Center in Yorktown Heights to see a quantum computer up close — thanks to Rogerio Baldini and Alexandre Pfeifer for making that possible. That visit already felt like a glimpse of the future. Today’s announcement makes that future feel even closer. The quantum decade is taking shape. Link in the first comment.

As we continue on our path to quantum computing at scale, Microsoft Quantum is innovating and advancing compute capabilities across our stack and the entire quantum ecosystem. Today, we are thrilled to share we're introducing a family of novel 4D geometric codes that can enable more efficient, reliable quantum computation from a variety of qubit types, including neutral atoms, ion traps, and photonics. These 4D geometric codes require few physical qubits per logical qubit, can correct errors in a single shot, and can improve the performance of quantum hardware with a 1,000-fold reduction in error rates.    Together with Atom Computing, our co-designed quantum work offers state-of-the-art quantum error correction, high-performance computing, advanced AI and our Microsoft Discovery platform to enhance exploration, research and development, and skilling in both scientific and non-scientific domains.    Utility-scale quantum computing is on the horizon, and it will be for everyone!    Learn more in Krysta Svore’s blog post: https://aka.ms/AQBlogQEC   #QuantumComputing #QEC #AI #HPC 

🚨 Europe now has a sovereign quantum cloud OVHcloud has just launched Quantum Platform, the first Quantum-as-a-Service (QaaS) offering, fully operated on EU soil, from cloud to quantum processor. At the core of this platform is Pasqal’s 100-qubit quantum processor. Unlike Google or IBM’s quantum machines, which need to be cooled to temperatures colder than outer space, Pasqal’s system uses lasers to hold individual atoms in place and it runs at room temperature. ➡️ Making it easier and more practical to operate, without sacrificing computing power. Why this launch matters 1️⃣ Tech stack independence EU companies and researches can run quantum workloads on a platform: ▫️ Built on EU quantum hardware ▫️ Hosted on EU cloud infrastructure ▫️ Governed under EU data laws 2️⃣ From emulation to execution OVHcloud has supported quantum exploration since 2022: now is moving to execution on real QPUs. The platform supports a hybrid environment: 🔸 Emulators for dev and prototyping 🔸 Live QPUs, starting with Pasqal, expanding to others by 2027 ➡️ Quantum R&D can scale from lab to live deployments in one environment, giving developers and enterprises a start in real-world readiness. 3️⃣ A platform OVHcloud is building a multi-vendor QPU platform. Their roadmap includes 8 quantum processors by 2027, with 7 from EU quantum startups - Photonic Inc., Trapped ion, Neutral Atom. 4️⃣ Competing differently The U.S. dominates quantum cloud today: ▪️ Amazon Web Services (AWS) Braket supports IonQ, Rigetti, and others ▪️ Microsoft Azure offers a range of backends, including Pasqal ▪️ Google is doubling down with its own superconducting chips ➡️ OVHcloud’s platform offers a trusted, local, and sovereign QaaS alternative, designed for Eu standards and governed under local laws, key for defense, health, public infrastructure, finance. 5️⃣ Catalyzing EU quantum adoption This platform opens the door for real-world quantum use cases: 💠 Post-quantum cryptography experiments 💠 Simulation of new materials or molecules 💠 Optimization in energy grids, logistics, and mobility ➡️ OVHcloud enables businesses and researchers to start using quantum technology, giving them flexible access and the power to run experiments from the cloud. OVHcloud’s platform is a strong signal: EU doesn’t need to choose between innovation and sovereignty. It can have both. Would love to hear your thoughts 💭 What use cases can benefit from this platform today? How can EU maintain its quantum momentum amid U.S.-China competition? #QuantumComputing #DigitalSovereignty #Europe #Cloud #Boardroom #StratEdge