Latest Developments in Quantum System Experiments

Another quantum computing breakthrough this week - scalable silicon qubits now from a real fab. Diraq + imec report >99% fidelity for all one and two qubit operations across four nominally identical silicon spin qubit unit cells made in an industry 300 mm CMOS flow. (Paper: Nature, “Industry compatible silicon spin qubit unit cells exceeding 99% fidelity” - https://lnkd.in/gQDRMa5u) State prep & measurement hit ~99.9%, with T₁ up to 9.5 s, T* ~40 µs, and Hahn echo T₂ up to ~1.9 ms. Benchmarking used gate set tomography (GST) - a stricter yardstick than RB - and pinpoints the dominant errors as stochastic dephasing from residual ²⁹Si nuclear spins, making isotopic purification the clearest path to ~99.9% class gates. (99.9% SPAM achieved for 3 of 4 devices tested). Why this matters: • CMOS compatibility + reproducibility across multiple devices = credible manufacturing pathway for large arrays. • Fidelities near surface code thresholds suggest tractable error correction overheads if extended to larger tiles. • Noise analysis indicates materials fixes (²⁸Si enrichment) rather than fundamental architectural roadblocks. What’s still hard: • Scaling control: parallel operation, global field schemes, and automation of calibration (today still manual). • Thermal budget with co integrated cryo CMOS control and operation at elevated temps. • Demonstrating error corrected logical qubits in this flow. Q Day lens: Foundry grade, high fidelity silicon qubits tighten timelines toward cryptographically relevant machines. If qubits and control can be tiled at CMOS densities while nudging fidelities to ~99.9%, the path to the millions of physical qubits needed for large scale Shor becomes much more plausible - underscoring the urgency of enterprise PQC migration and crypto agility roadmaps now, not later. Paper is: Nature (Sept 2025), “Industry compatible silicon spin qubit unit cells exceeding 99% fidelity” - https://lnkd.in/gQDRMa5u

World-First Molecular Quantum Entanglement Achieved at Durham University In a groundbreaking achievement, scientists at Durham University in the UK have successfully demonstrated quantum entanglement of molecules with a record-breaking fidelity of 92%. This marks the first time entanglement has been achieved with molecules, advancing quantum mechanics research and opening doors to revolutionary technologies in communication, sensing, and computing. Key Highlights: 1. Quantum Entanglement Basics: Quantum entanglement links particles such that the state of one influences the other, regardless of distance. This phenomenon is a cornerstone for developing next-generation quantum technologies, enabling faster communication and enhanced computational power. 2. ‘Magic-Wavelength’ Optical Tweezers: The team utilized highly precise optical traps known as magic-wavelength optical tweezers to create environments supporting long-lasting molecular entanglement. These advanced tools allowed for stable control and manipulation of molecular states. 3. Applications: • Quantum Networking: Entanglement over existing fiber optic cables could accelerate the real-world deployment of quantum networks without requiring extensive new infrastructure. • Quantum Computing and Sensing: Molecules, with their complex internal structures, offer new dimensions for computation and precision sensing, potentially surpassing the capabilities of entangled atoms. 4. Major Milestone: While entanglement between atoms has been repeatedly demonstrated, molecules bring added complexity due to their additional internal structures. Achieving high-fidelity entanglement with molecules is a significant step forward in the field. Implications for the Future: This breakthrough could lead to advancements in secure communication, more powerful quantum computers, and sophisticated sensing technologies. As quantum entanglement becomes more applicable to real-world systems, innovations like this set the stage for transformative developments in science and technology.

For those tracking progress in Quantum… As my colleague Hartmut Neven has predicted, real-world applications possible only on quantum computers are much closer than people think – as near as five years, even though fully error corrected quantum computers may be further away.  Recently, my colleagues on our Quantum AI team at Google Research took another important step on that path with a new set of results we published last week in Nature that share a promising new approach to applications on today’s quantum computers. Our analog-digital quantum simulator using super-conducting qubits shows performance beyond the reach of classical simulations in cross-entropy benchmarking experiments. Simulations with the level of experimental fidelity in this simulator would require more than a million years on a Frontier supercomputer. The simulator brings together digital’s flexibility and control with the analog’s speed – and provides a path towards applications that cannot be accomplished on a classical computer. Along the way, my colleagues also made a scientific discovery – they observed the breakdown of a well-known prediction in non-equilibrium physics, the Kibble-Zurek mechanism - an important result in our understanding of magnetism, and also useful in various kinds of quantum simulations. Congratulations to Trond Andersen, Nikita Astrakhantsev, and the rest of the team on this exciting step – much more to come! You can read the Nature paper here: https://lnkd.in/gg2En5qe 

The last two days have seen two extremely interesting breakthroughs announced in quantum computing. There is a long path ahead, but these both point to the potential for dramatically upscaling ambitions for what's possible in relatively short timeframes. The most prominent advance was Microsoft's announcement of Majorana 1, a chip powered by "topological qubits" using a new material. This enables hardware-protected qubits that are more stable and fault-tolerant. The chip currently contains 8 topologic qubits, but it is designed to house one million. This is many orders of dimension larger than current systems. DARPA has selected the system for its utility-scale quantum computing program. Microsoft believes they can create a fault-tolerant quantum computer prototype in years. The other breakthrough is extraordinary: quantum gate teleportation, linking two quantum processes using quantum teleportation. Instead of packing millions of qubits into a single machine—which is exceptionally challenging—this approach allows smaller quantum devices to be connected via optical fibers, working together as one system. Oxford University researchers proved that distributed quantum computing can perform powerful calculations more efficiently than classical systems. This could not only create a pathway to workable quantum computers, but also a quantum internet, enabling ultra-secure communication and advanced computational capabilities. It certainly seems that the pace of scientific progress is increasing. Some of the applications - such as in quantum computing - could have massive implications, including in turn accelerating science across domains.

🚨 Exciting #quantumcomputing alert! Now #QEC primitives actually make #quantumcomputers more powerful! 75 qubit GHZ state on a superconducting #QPU 🚨 In our latest work we address the elephant in the room about #quantumerrorcorrection - in the current era where qubit counts are a bottleneck in the systems available, adopting full-blown QEC can be a step backwards in terms of computational capacity. This is because even when it delivers net benefits in error reduction, QEC consumes a lot of qubits to do so and we just don't have enough right now... So how do we maximize value for end users while still pushing hard on the underpinning QEC technology? To answer this the team at Q-CTRL set out to determine new ways to significantly reduce the overhead penalties of QEC while delivering big benefits! In this latest demonstration we show that we can adopt parts of QEC -- indirect stabilizer measurements on ancilla qubits -- to deliver large performance gains without the painful overhead of logical encoding. And by combining error detection with deterministic error suppression we can really improve efficiency of the process, requiring only about 10% overhead in ancillae and maintaining a very low discard rate of executions with errors identified! Using this approach we've set a new record for the largest demonstrated entangled state at 75 qubits on an IBM quantum computer (validated by MQC) and also demonstrated a totally new way to teleport gates across large distances (where all-to-all connectivity isn't possible). The results outperform all previously published approaches and highlight the fact that our journey in dealing with errors in quantum computers is continuous. Of course it isn't a panacea and in the long term as we try to tackle even more complex algorithms we believe logical encoding will become an important part of our toolbox. But that's the point - logical QEC is just one tool and we have many to work with! At Q-CTRL we never lose sight of the fact that our objective is to deliver maximum capability to QC end users. This work on deploying QEC primitives is a core part of how we're making quantum technology useful, right now. https://lnkd.in/gkG3W7eE

The preparation of GHZ states is a common benchmark for quantum processors. These states are not only a test of device-wide entanglement, they are also useful resources in numerous quantum algorithms. Our team recently demonstrated a 120-qubit logical GHZ state on our Heron r2 processors, the largest reported on any hardware. This includes a 60-logical qubit GHZ on a single-shot basis (i.e. with no readout error mitigation). These experiments were enabled by error detection both at the device and circuit level. At the device level, we can use our knowledge of the device architecture to detect if some couplers fail during a particular shot. At the circuit level, we can use symmetries inherent in the GHZ state to detect if certain violations occur. The state preparation proceeds as follows: we first eliminate some edges with bad CZ or bad readout (above a given threshold). Then, starting from a qubit at the center of the remaining graph, we perform a breadth-first search (BFS) to prepare a GHZ state in shallow depth. During the BFS, some nodes are randomly blocked in order to increase the chance of check qubits being found. Afterwards, any node that does not belong to the GHZ but is adjacent to 2 of its qubits may act as a check in a ZZ parity measurement. We aim to maximize the ''coverage'' of checks that we can find through this randomization, while not increasing the depth beyond a given threshold above the best possible depth. The coverage of checks is the number of locations in the circuit whose failure is detected by one of the checks, which we can compute efficiently using Pauli propagation. Therefore, we can predict exactly how many failures will be detected using our checks, and can optimize the layout for them. These experiments were performed by Ali Javadi and Simon Martiel. They also leverage many of the recent advances made by our team, including improved readout on Herons, characterization of coupler errors, and M3 readout error mitigation. For comparison, the recent demonstrations by Microsoft/Atom with a 24-qubit GHZ, Quantinuum with a 50-qubit GHZ, and Q-ctrl with a 75-qubit GHZ (also on Heron) also relied on error detection. As we chart the path towards advantage all that really matters is how large a quantum circuit can we run and can we trust the method used gives accurate results. While GHZ are simple to simulate this method shows that error detection with post selection is a potentially viable tool to add with error mitigation or sample based quantum diagonalization, to run experiments at the utility scale (100+ qubits) and build the set of trusted tools to search for quantum advantage on near term devices. This is why we are pushing near term methods such as error mitigation, error detection on utility-scale (100+ qubits) quantum computers.

Quantum Entanglement — a Theory No One Talked about ForEver — recently — Recent Developments in Quantum Entanglement Research (as of January 2026) Quantum entanglement, a cornerstone of quantum mechanics where particles remain interconnected regardless of distance, has seen significant advancements in 2025. These breakthroughs focus on practical applications like quantum computing, networking, communication, and sensing, overcoming challenges such as decoherence, scalability, and environmental constraints. Below is a summary of key research highlights from the past year, drawn from peer-reviewed studies, institutional announcements, and expert discussions. 1. Room-Temperature Quantum Entanglement for Signaling Researchers at Stanford University developed a nanoscale device that entangles photons and electrons at room temperature, eliminating the need for cryogenic cooling. Led by Jennifer Dionne and Feng Pan, the device uses a thin layer of molybdenum diselenide (MoSe₂) on nanopatterned silicon to generate "twisted light," enabling stable spin coupling between photons and electrons. This could lead to affordable quantum components for cryptography, AI, and high-speed data transmission. Similar discussions on X highlighted its potential for quantum networking, including integration with CMOS chips for long-distance entanglement distribution. 2. Discovery of a New Type of Quantum Entanglement A team from the Technion - Israel Institute of Technology identified a novel form of entanglement in the total angular momentum of photons within nanoscale structures. Published in Nature, the study by Amit Kam and Shai Tsesses shows photons entangling solely via angular momentum, expanding the quantum state space. This is the first new entanglement type in over two decades and could enable miniaturized quantum devices for communication and computing. 3. Entanglement of Atomic Nuclei for Scalable Quantum Computing At the University of New South Wales (UNSW), Andrea Morello's group achieved entanglement between phosphorus atomic nuclei in silicon chips, using electrons as intermediaries over 20-nanometer distances. This "geometric gate" approach makes nuclear spin qubits compatible with standard silicon fabrication, addressing noise and scalability issues. It paves the way for integrating reliable qubits into everyday electronics, potentially accelerating large-scale quantum computers. Related X posts noted broader quantum computing progress, including spectral gap estimation with 20 qubits.

Delighted to share some work we've been developing over the past months! 📄 🔗🔗 https://lnkd.in/enXEQdDc 🔗🔗 ✨ Building on our previous research [https://lnkd.in/eCjCDv2D], we've explored a new direction for modular quantum computing with surface codes. The focus is on whether emission-based hardware can support fault-tolerant quantum error correction. The question we set out to answer: 🤔 📡 Can we distribute entanglement across modules without relying on slow and noisy two-qubit gates? 🔗 Our earlier work showed emission-based platforms were feasible but limited to thresholds of 0.16 % ⚡ Is there a more efficient protocol path forward? Our approach: 🎯 We propose single-shot GHZ state generation — creating the entangled states needed for stabilizer measurements directly, without Bell-pair fusion. The optical setup generates Bell pairs, W states, and GHZ states by simply observing photon detection patterns. Benchmarking on realistic hardware: 🧪 #DiamondColorCenters #QuantumHardware 🔴 We modeled this for diamond color-center platforms (what experimentalists are actually building) 🔴 Full noise modeling includes photon loss, detector efficiency, and circuit-level errors 🔴 Both photon-number-resolving and standard detectors analyzed The findings: 📊 We're grateful for what the analysis reveals about this architecture with circuit-level noise: 💎 Threshold of 0.24 % with photon-number-resolving detectors 💎 Threshold of 0.19 % with standard detectors 💎 These thresholds scale with hardware improvements — unlike previous approaches that saturated Why this matters: 🛣️ #FaultTolerance #ModularQuantumComputing #QuantumErrorCorrection This work suggests a practical pathway toward scalable modular quantum computers using hardware that's already being developed in labs. The protocols require only modest enhancements to existing emission-based setups. Looking ahead: 🔮 #ExperimentalQuantum #QuantumNetworks #DistributedQuantum We hope these results help guide the experimental community's next steps. We've tried to provide clear hardware targets and realistic thresholds that could inform near-term implementations. Special thanks to our collaborators at QuTech, Keio University, and OIST for making this collaborative effort possible. 🙏 Daniel Bhatti, Rikiya Kashiwagi, David Elkouss, Kazufumi Tanji, Wojciech Roga, Masahiro Takeoka #QuantumComputing #SurfaceCode #Photonics #ColorCenters #QuantumErrorCorrection #ModularArchitectures #QuantumInternet

Quantum Experiments Shrunk to a Palm-Sized Chip A team at the University of California, Santa Barbara has managed to compress an entire physics laboratory into the size of a microchip. Experiments with cold atoms — once spread across rooms filled with optical tables — now fit on compact silicon nitride chips. Cold atoms form the basis of the most precise measurements in the universe. Atoms are trapped with lasers, cooled almost to absolute zero, and their quantum properties are used to measure time with billionth-of-a-second precision, detect gravitational anomalies, and search for dark matter. The problem: traditional setups occupy entire rooms with optical tables, racks of lasers, and vibration isolation systems. The breakthrough came in 2023. Daniel Blumenthal’s team created PICMOT — a photonic integrated 3D magneto-optical trap. Silicon nitride waveguides deliver laser beams into a vacuum chamber filled with rubidium vapor. Three beams cross the atoms, reflect off mirrors, and return, forming an intersection region. Magnetic coils complete the trap. The system captured a million atoms and cooled them to –273 °C. Then came the next challenge: why not fit the entire optical table on a chip? Lasers, mirrors, modulators, stabilizers, frequency shifters — everything that manipulates light. In 2024, the team solved the problem of noisy lasers. Commercial lasers have broad, unstable linewidths — useless for quantum precision. They took an ordinary Fabry-Perot diode laser worth a few dollars and passed it through on-chip resonators and waveguides. The result: a stable single-frequency light source comparable to lab-grade systems. Moreover, the compact geometry provides faster feedback, reducing noise and improving stability. The potential applications extend far beyond the lab. Portable cold-atom systems could measure sea-level rise with centimeter accuracy, detect underground structures, and track glacier movement. Earthquakes might be detectable hundreds of kilometers away by sensing shifts in the gravitational field. The vacuum chamber and atom source remain bulky for now — miniaturizing them while maintaining large atom counts is still a challenge. But the team is working on it. Their goal: a palm-sized device capable of replacing an entire quantum laboratory.

As this year comes to an end, let us list some important discoveries and milestones in quantum computing in 2025. 1. Verifiable Quantum Advantage with the Quantum Echoes Algorithm: Researchers at Google Quantum AI announced the Quantum Echoes algorithm, demonstrating a verifiable quantum advantage on the Willow quantum chip. It showcased a time-correlation problem roughly 13,000× faster than the best classical supercomputers. 2. IBM Advances Roadmap Toward Fault-Tolerant Quantum Computing: IBM unveiled significant progress on its path to fault-tolerant quantum computing, showing new processor designs and software infrastructure aimed at achieving quantum advantage by 2026 and true fault tolerance by 2029. 3. Harvard’s Quantum Computer: A team from Harvard reported the first continuously operating quantum computer, capable of running for extended periods (e.g., over two hours in experiments) without restarting. This addresses key challenges such as atom loss in neutral-atom systems and is a crucial step toward scalable, uninterrupted quantum computation. 4. Breakthroughs in Error Suppression and Coherence: 2025 saw new experimental techniques, including algorithmic fault tolerance that reduce the overhead of error correction by up to 100× and push physical qubits to record low error rates, crucial for scalable quantum systems. Improved coherence and error suppression methods are foundational for moving from noisy intermediate-scale devices toward larger, reliable quantum computers. 5. Record-Sized Neutral-Atom Qubit Arrays: Caltech researchers built one of the largest neutral-atom qubit arrays (~6,100 qubits) with exceptional coherence times and high manipulation accuracy, a key milestone for platforms that can scale without losing quantum information. 6. Oxford Breakthrough in Distributed Quantum Computing: Oxford University demonstrated quantum teleportation of logic gates between separate quantum processors over optical links, enabling modular quantum computing. This achievement is a major step toward a quantum internet and scalable distributed quantum processing. 7. Progress Toward Topological Qubits: Microsoft announced Majorana 1, a topological quantum processor designed to host Majorana zero modes — exotic quasiparticles that could inherently reduce errors and simplify scaling to fault-tolerant systems. While still experimental, this represents a significant materials-based approach to robust quantum hardware. Though not a full list. There are other important discoveries too. Quantum Computing is progressing beyond expectations! #quantumcomputing #quantumtechnology #discovery #breakthrough