量子ニュース

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This week the news worth reading wasn't a qubit count — it was the plumbing. Three announcements, all about the unglamorous engineering that fault tolerance actually runs on. Quobly, the Grenoble silicon-spin startup spun out of CEA-Leti and CNRS, closed a €115M ($133.5M) Series A to build its first machine, Alloy Pioneer, on the same FD-SOI 300mm wafers that ordinary chips already use. There's no qubit count yet and no published gate fidelities, so this is a manufacturing bet, not a hardware result — but it's the right bet: if silicon-spin qubits work at all, the whole reason to care is that you could print them in an existing CMOS line instead of hand-building them one at a time. QuiX Quantum, in the Netherlands, installed something even less photogenic and more important — a feed-forward control unit that reads a single-photon detector and reconfigures the optical chip in about 150 nanoseconds, before the photon has traveled 30 meters down the fiber. Measurement-based photonic quantum computing simply doesn't work without real-time feedback this fast, so this is a real piece of the fault-tolerance puzzle clicking in, not a press-release number. And Hamamatsu Photonics, NKT Photonics, and Yaqumo signed a Japan–Denmark agreement to standardize the lasers, detectors, and optical modules that cold-atom machines need — the quiet supply-chain work that decides whether any of this scales past one lab bench. None of the three is a breakthrough in the physics. They're all engineering, and engineering is where the entire game sits right now. We'll take three boring announcements about wafers, FPGAs, and lasers over one more chart of rising qubit counts.

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Three stories this week, all circling the same question: how close is fault tolerance, really. Atom Computing reported the first full demonstration of quantum error correction with a toric code on a neutral-atom machine — sustained over many rounds, with logical error rates that fall as you add physical qubits. That last part is the whole game: it's the 'below threshold' behavior that says error correction is helping rather than hurting, and it puts neutral atoms next to the superconducting and trapped-ion groups that have shown the same thing. Microsoft used its Build conference to report 'Majorana 2' progress: swapping aluminum for lead in the superconducting stack lifted the measured topological gap to about 70 µeV (from roughly 30) and pushed parity lifetimes to about 22 seconds, up from the 1–12 millisecond range of earlier devices. Those are real improvements in the numbers — but the underlying claim that these are genuine topological qubits has been walked back before, so we're filing it under promising, not settled. And D-Wave, the annealing company, published a gate-model roadmap built on a dual-rail superconducting qubit that catches about 90% of errors mid-computation, with 99.9% two-qubit fidelity under error detection and a target of 100 logical qubits by 2032. The fidelity is a real measured number; the 2032 date and the 10× error-suppression-per-round claim are projections, and D-Wave has a long record of letting the roadmap outrun the hardware. Worth watching, not worth pre-ordering.

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Three stories worth tracking. TreQ brought online a multi-vendor Open-Architecture Quantum testbed in Oxfordshire that can swap between eight different processor + control + software combinations via software alone — no recabling, no thermal cycling — integrating Rigetti's Novera, QuantWare boards, and a Maybell cryostat in a single three-rack footprint. The bet is that vendor-neutral interfaces matter more than any single hardware bet as the field consolidates. Separately, Quantum Machines and Qruise pushed the calibration story further: they automated the bring-up of a 21-qubit QuantWare Contralto QPU at the Israeli Quantum Computing Center down to 15 minutes — calibration normally takes days of hand-tuning by experts. And in commercial news, Qubit Pharmaceuticals (Paris) and Singapore's Centre for Quantum Technologies announced a two-year partnership running quantum chemistry algorithms — including the first experimental quantum Markov Chain Monte Carlo on Quantinuum's trapped ions — directly aimed at drug discovery workflows.

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On World Quantum Day (April 14), DARPA launched the Heterogeneous Architectures for Quantum (HARQ) program to combine different qubit modalities — trapped ions, neutral atoms, and superconducting qubits — into a single networked system, betting that mixing qubit types will outperform any single approach at scale. IonQ was selected as a HARQ contractor, sending the stock up 21%, and memQ was tapped to build a hardware-aware quantum compiler for the program. Separately, ParityQC set a new benchmark by running a 52-qubit Quantum Fourier Transform on IBM's Heron processor — the largest QFT demonstrated on real hardware — using a parity mapping that reduces circuit depth significantly. Meanwhile, the UK confirmed it is the first country to deploy quantum computers at scale under a national advanced market commitment, with systems earmarked for defense, healthcare, and national security applications.

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Monarch Quantum closed a $55M oversubscribed growth round today — six months after founding and already past $115M in total capital and contracts — to scale production of its Quantum Light Engines, which replace bench-top optical systems with integrated photonic modules for quantum computing, sensing, and networking. Meanwhile, Google's March 2026 study on elliptic-curve cryptography continued dominating coverage: the paper shows that ECDLP-256 (the math protecting Bitcoin, Ethereum, and most TLS connections) may be breakable with fewer than 1,200 logical qubits and roughly 90 million Toffoli gates — about 100× fewer operations than RSA-2048 and 10× fewer resources than earlier estimates. No machine today is anywhere close to those logical-qubit counts, but the trajectory is no longer abstract. And IonQ confirmed a deal with Singapore-based Horizon Quantum to deliver a 6th-generation chip-based 256-qubit trapped-ion system — 256 qubits with all-to-all connectivity and 99.99% two-qubit gate fidelity — expanding Horizon's multi-modal testbed.

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Q-CTRL published a preprint (arXiv:2604.06319) proposing a heterogeneous architecture called Q-NEXUS that splits quantum systems into separate modules for logic, storage, and resource generation. By offloading the 96–97% of qubit cycles that sit idle in algorithms like RSA-2048 into dedicated quantum memory tiers, the framework achieves a 138x reduction in physical qubit requirements for fault-tolerant benchmarks and a 551x reduction in algorithmic logical errors for specific subroutines — with long-range coupling, 2048-bit RSA factoring drops to around 190,000 qubits and under 10 days. On the application side, Pasqal and Saudi firm True Nexus announced a partnership to simulate alternative protein gelation using neutral-atom hardware, which is an early test of whether quantum simulation can displace trial-and-error in food science. And ahead of World Quantum Day on April 14, Andhra Pradesh is launching India's first indigenous open-access quantum computing testing facility at SRM University in Amaravati — part of the National Quantum Mission and an Amaravati Quantum Valley initiative targeting international research partnerships.

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Riverlane published benchmark numbers for its Deltaflow 2 error-correction stack: mean QEC latency of 16.32µs, a 4× improvement over Google Willow's 63µs benchmark and a 4× improvement in decoder throughput. The system handles up to 250 physical qubits and uses Riverlane's Local Clustering Decoder running on custom hardware — this is the layer that has to run fast enough that error correction doesn't become the bottleneck before the computation finishes. Separately, Los Alamos researchers showed that quantum learning models designed to avoid barren plateaus — a training problem where gradients vanish — turn out to be classically simulable, which deflates a substantial part of the quantum machine learning literature that assumed avoiding barren plateaus was sufficient for quantum advantage. And IQM opened its first US Quantum Technology Center in Maryland's Discovery District, partnering with the Capital of Quantum initiative to embed IQM hardware and engineering in one of the denser quantum ecosystems in the country.

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The quantum cryptography threat timeline is compressing faster than most security teams planned for. A CalTech/Oratomic joint paper concluded this week that breaking standard encryption may require as few as 10,000 qubits — not the millions cited in older estimates — and Google has moved its internal post-quantum migration deadline to 2029 after publishing research showing a 20x reduction in the qubit count needed to crack 256-bit elliptic curve cryptography. Nobel laureate John Martinis was direct about what that means for Bitcoin: when a transaction's public key is briefly exposed on-chain before block confirmation, a capable quantum computer could derive the private key in minutes, though he estimates the community has 5–10 years to migrate. On the hardware side, Singapore-based Horizon Quantum is acquiring a 256-qubit IonQ trapped-ion system — 99.99% gate fidelity, all-to-all connectivity — making it one of the few software-focused labs running a commercial system at that scale, which it plans to use for testing hardware-agnostic application stacks.

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Rigetti made its 108-qubit Cepheus-1-108Q generally available on both Quantum Cloud Services and Amazon Braket — the system uses a chiplet-based modular design and hits 99.1% median two-qubit gate fidelity at 60ns gate speed, tripling the qubit count from the prior generation. Researchers at Quantum Art in Israel published a new trapped-ion approach that drives all motional modes of an ion crystal simultaneously, letting a small set of global and semi-global pulses produce any multi-qubit gate without single-ion addressing hardware. IQM and Fraunhofer FOKUS pushed Qrisp to version 0.8, which produced the first concrete gate-level compilation of Shor's algorithm for 2048-bit RSA factoring — previous estimates were theoretical; this one has an exact qubit budget. And a team at NTNU developed a method to measure superconducting qubit coherence time roughly 100x faster than before, cutting measurement latency from ~1 second to ~10ms and making real-time error diagnostics viable.

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Quantinuum published results from their 98-qubit Helios processor showing 48 error-corrected logical qubits at a near 2:1 physical-to-logical ratio using Iceberg codes — a year ago, conventional wisdom said you'd need hundreds or thousands of physical qubits per logical qubit. Separately, Fujitsu and the University of Osaka announced a framework that cuts the qubit requirements for a molecular energy calculation by 80×, bringing a workload from thousands of years down to about 35 days on near-term hardware. And Conductor Quantum released CODA MCP, which lets AI coding assistants like Claude drive real quantum hardware from your editor — 1,000+ qubits across IBM, IonQ, Rigetti, and Quantinuum, no account setup needed.

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