IQM generates GHZ state across all 54 qubits; fidelity 0.516 after REM

【Article Title】 IQM generates GHZ state across all 54 qubits; fidelity 0.516 after REM 【Article Body】 AI TRANSLATION This article is an AI-generated translation of the original Japanese article. For the authoritative version, please refer to the original. Read the original Japanese article → (https://quantumindex.jp/iqm-emerald-54-qubit-ghz-entanglement/) IQM Quantum Computers announced it has succeeded in generating a Greenberger–Horne–Zeilinger (GHZ) state across all 54 qubitsqubitsQubit / Quantum Bit / QubitThe basic unit of information in a quantum computer. It can represent not only 0 or 1 but also a quantum state that is a superposition of them.QI NoteHaving more qubits does not necessarily mean higher performance. Error rates, connectivity, coherence time, and the number of logical qubits are also important. of its cloud-accessible superconducting quantum computersuperconducting quantum computerSuperconducting Quantum Computing / Superconducting Quantum Computing / Superconducting QubitAn implementation approach for quantum computers that operates superconducting circuits at ultra-low (cryogenic) temperatures and uses electrical quantum states as quantum bits (qubits).QI NoteCharacterized by fast gate operations, but performance is not determined by qubit count alone. Gate fidelity, coherence time, connectivity, and support for error correction should also be verified., IQM Emerald. The fidelity at 54 qubits was 0.516 after applying readout-error mitigation (REM), exceeding the classical entanglement threshold of 0.500. ✍️ Quantum Index Analysis We explain the technical and business significance behind the announcement and evaluation points that numbers and headlines may not reveal. Read our independent analysis ↓ Announcement overview In this demonstration, IQM generated a GHZ stateGHZ stateGreenberger–Horne–Zeilinger State / GHZ StateAn entangled quantum state of three or more qubits that is a superposition of the state in which all qubits are 0 and the state in which all qubits are 1. It is used as a representative indicator to verify entanglement spanning multiple qubits.QI NoteThe scale at which GHZ states can be generated is one indicator of a quantum computer’s multi-qubit control performance. A fidelity exceeding 0.5 constitutes evidence of genuine multipartite entanglement, but this does not directly demonstrate practical performance in quantum computation or quantum advantage. — a standard benchmark for large-scale entanglement — across all 54 qubits of the IQM Emerald processor. According to IQM, the fidelity was 0.515 for 40 qubits without REM, and 0.516 for 54 qubits after applying REM. IQM credits an automatic state-preparation routine, which selects qubits and gate ordering based on two-qubit gate fidelities and qubit idle times, with contributing to the result. Alongside about a year of improvements to hardware and calibration methods, IQM also updated its gate set, implemented dynamic decoupling, and adjusted qubit selection, claiming reductions in quantum operation error rates by up to 50%. IQM says that whereas comparable demonstrations had been reliably usable at around 30 qubits, cloud users can now access the full processor performance and related tools. Key points • Generated a GHZ state across the full 54-qubit superconducting processor, IQM Emerald. • Fidelity was 0.515 for 40 qubits without REM, and 0.516 for 54 qubits after applying REM, exceeding the classical threshold of 0.500. • An automatic state-preparation routine selected qubits and gate order based on gate fidelities and idle times. • IQM reports up to a 50% reduction in quantum operation error rates through calibration and gate-set improvements, dynamic decoupling, and qubit selection. • Cloud users can access the full 54-qubit processor performance and associated tools. Technical and business significance Technically, the significance lies in entangling all 54 qubits in a single GHZ circuit rather than using only part of the chip, and maintaining fidelity above the entanglement threshold. The automation of state preparation and calibration appears to have helped suppress idle-time and gate-induced errors in a large circuit. From a business perspective, IQM states that cloud users can now use the entire processor beyond the roughly 30-qubit scale previously available, which could expand the size of runnable circuits. However, the 54-qubit result relies on REM, and IQM has not disclosed whether this translates into improved performance for concrete commercial applications, pricing, or service terms. What to watch next Going forward, it will be important to see the fidelity at 54 qubits without REM and whether the result is reproducible. It will also be informative to determine if the full chip can be effectively used for circuits other than GHZ and whether that yields tangible improvements in computational performance. Attention should also focus on cloud pricing and access conditions, as well as external validation and published user case studies. ✍️ Quantum Index Analysis This result is notable because it demonstrates many-body entanglement using all 54 qubitsqubitsQubit / Quantum Bit / QubitThe basic unit of information in a quantum computer. It can represent not only 0 or 1 but also a quantum state that is a superposition of them.QI NoteHaving more qubits does not necessarily mean higher performance. Error rates, connectivity, coherence time, and the number of logical qubits are also important. of IQM Emerald. However, a fidelity of 0.516 only slightly exceeds the 0.500 threshold and does not by itself demonstrate high-quality 54-qubit computation. The GHZ stateGHZ stateGreenberger–Horne–Zeilinger State / GHZ StateAn entangled quantum state of three or more qubits that is a superposition of the state in which all qubits are 0 and the state in which all qubits are 1. It is used as a representative indicator to verify entanglement spanning multiple qubits.QI NoteThe scale at which GHZ states can be generated is one indicator of a quantum computer’s multi-qubit control performance. A fidelity exceeding 0.5 constitutes evidence of genuine multipartite entanglement, but this does not directly demonstrate practical performance in quantum computation or quantum advantage. is a fundamental benchmark for large-scale entanglement, but it does not directly indicate performance on general quantum algorithms. IQM Emerald is a 54-physical-qubit superconducting quantum processorquantum processorQuantum Processor / Quantum Processor / Quantum Processing Unit / QPUThe central part of the hardware that houses qubits and performs quantum computational operations such as quantum gates and measurements.QI NoteThe performance of a QPU cannot be judged by the number of qubits alone. Gate fidelity, connectivity, speed, error rates, and other factors must be considered together. (QPU) offered via the cloud since 2025. IQM’s system products include Radiance, which targets NISQNISQNoisy Intermediate-Scale Quantum / NISQA term for quantum devices of roughly tens to thousands of qubits that include noise and do not have sufficient error correction, or for the technological stage they represent.QI NoteIt is not a classification defined by a strict qubit count. Because it broadly refers to devices prior to FTQC, one needs to examine specific error rates and the circuits that can be executed. computing, and the next-generation Halocene, which emphasizes quantum error correctionquantum error correction量子誤り訂正 / Quantum Error Correction / QECA technique that distributes information across multiple physical qubits and detects and corrects errors without directly disturbing the quantum state.QI NoteSimply implementing it does not automatically provide practical fault tolerance. What matters is whether the logical error rate is improved relative to the physical error rate.. Emerald sits in the same 54-qubit class as Radiance; this result stems from calibration, control, and circuit-optimization improvements on the existing QPU rather than from the new Halocene architecture. One point to note is that fidelity was 0.515 at 40 qubits without readout-error mitigation (REM), whereas the 54-qubit figure of 0.516 is reported after applying REM. Because the measurement conditions differ, one cannot conclude that fidelity was maintained simply by increasing the qubit count. The margin above the threshold is only 0.016, so verification that accounts for statistical uncertainty is important. On the other hand, automatic optimization of state preparation based on gate fidelitygate fidelityGate Fidelity / Gate Fidelity / Quantum Gate FidelityA measure of accuracy that indicates how closely a quantum gate operation was performed compared to the ideal operation.QI NoteHigher is generally better, but values depend on the measurement method and differ between single-qubit and two-qubit gates. When comparing, also check the evaluation conditions. and idle time is a practically meaningful improvement. Still, this demonstration used a specific GHZ circuit across all 54 qubits and does not guarantee improved performance for general workloads across the processor. Future evaluation should focus on 54-qubit fidelity without REM, performance on more complex circuits, and results for practical quantum algorithms. NETWORKExplore IQM’s industry network → (/qi-network/) Related articles • D-Wave launches beta of gate-model quantum simulator, ahead of dual-rail hardware (https://en.quantumindex.jp/dwave-gate-model-simulator-beta/) • IQM to deliver 5-qubit “Spark” to Eldorado in Brazil — first South American deployment (https://en.quantumindex.jp/iqm-eldorado-brazil-quantum-computer/) • Toyo Technica to install two IQM quantum computers, aiming to set up G-QuAT and domestic go-to-market strategy (https://en.quantumindex.jp/toyo-iqm-quantum-computers-japan-access/) Source Read the original press release (https://iqm.gcs-web.com/news-releases/news-release-details/iqm-demonstrates-entanglement-across-complete-54-qubit-processor) If you found this article useful, please consider sharing it. ──────────────────── 【AI Evaluation Request】 Evaluate the following article critically, not based on the quality of its writing, but on its **original informational value as a specialist publication**. Do not give a high rating to summaries, paraphrases, explanations of technical terms, or generic observations such as "this will be worth watching" or "the timeline remains uncertain" if they could easily be produced by a general-purpose generative AI, even if they are well written. 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IQM Quantum Computers announced it has succeeded in generating a Greenberger–Horne–Zeilinger (GHZ) state across all 54 qubitsqubitsQubit / Quantum Bit / QubitThe basic unit of information in a quantum computer. It can represent not only 0 or 1 but also a quantum state that is a superposition of them.QI NoteHaving more qubits does not necessarily mean higher performance. Error rates, connectivity, coherence time, and the number of logical qubits are also important. of its cloud-accessible superconducting quantum computersuperconducting quantum computerSuperconducting Quantum Computing / Superconducting Quantum Computing / Superconducting QubitAn implementation approach for quantum computers that operates superconducting circuits at ultra-low (cryogenic) temperatures and uses electrical quantum states as quantum bits (qubits).QI NoteCharacterized by fast gate operations, but performance is not determined by qubit count alone. Gate fidelity, coherence time, connectivity, and support for error correction should also be verified., IQM Emerald. The fidelity at 54 qubits was 0.516 after applying readout-error mitigation (REM), exceeding the classical entanglement threshold of 0.500.

Announcement overview

In this demonstration, IQM generated a GHZ stateGHZ stateGreenberger–Horne–Zeilinger State / GHZ StateAn entangled quantum state of three or more qubits that is a superposition of the state in which all qubits are 0 and the state in which all qubits are 1. It is used as a representative indicator to verify entanglement spanning multiple qubits.QI NoteThe scale at which GHZ states can be generated is one indicator of a quantum computer’s multi-qubit control performance. A fidelity exceeding 0.5 constitutes evidence of genuine multipartite entanglement, but this does not directly demonstrate practical performance in quantum computation or quantum advantage. — a standard benchmark for large-scale entanglement — across all 54 qubits of the IQM Emerald processor. According to IQM, the fidelity was 0.515 for 40 qubits without REM, and 0.516 for 54 qubits after applying REM. IQM credits an automatic state-preparation routine, which selects qubits and gate ordering based on two-qubit gate fidelities and qubit idle times, with contributing to the result. Alongside about a year of improvements to hardware and calibration methods, IQM also updated its gate set, implemented dynamic decoupling, and adjusted qubit selection, claiming reductions in quantum operation error rates by up to 50%. IQM says that whereas comparable demonstrations had been reliably usable at around 30 qubits, cloud users can now access the full processor performance and related tools.

Key points

• Generated a GHZ state across the full 54-qubit superconducting processor, IQM Emerald.
• Fidelity was 0.515 for 40 qubits without REM, and 0.516 for 54 qubits after applying REM, exceeding the classical threshold of 0.500.
• An automatic state-preparation routine selected qubits and gate order based on gate fidelities and idle times.
• IQM reports up to a 50% reduction in quantum operation error rates through calibration and gate-set improvements, dynamic decoupling, and qubit selection.
• Cloud users can access the full 54-qubit processor performance and associated tools.

Technical and business significance

Technically, the significance lies in entangling all 54 qubits in a single GHZ circuit rather than using only part of the chip, and maintaining fidelity above the entanglement threshold. The automation of state preparation and calibration appears to have helped suppress idle-time and gate-induced errors in a large circuit. From a business perspective, IQM states that cloud users can now use the entire processor beyond the roughly 30-qubit scale previously available, which could expand the size of runnable circuits. However, the 54-qubit result relies on REM, and IQM has not disclosed whether this translates into improved performance for concrete commercial applications, pricing, or service terms.

What to watch next

Going forward, it will be important to see the fidelity at 54 qubits without REM and whether the result is reproducible. It will also be informative to determine if the full chip can be effectively used for circuits other than GHZ and whether that yields tangible improvements in computational performance. Attention should also focus on cloud pricing and access conditions, as well as external validation and published user case studies.

✍️ Quantum Index Analysis

This result is notable because it demonstrates many-body entanglement using all 54 qubitsqubitsQubit / Quantum Bit / QubitThe basic unit of information in a quantum computer. It can represent not only 0 or 1 but also a quantum state that is a superposition of them.QI NoteHaving more qubits does not necessarily mean higher performance. Error rates, connectivity, coherence time, and the number of logical qubits are also important. of IQM Emerald. However, a fidelity of 0.516 only slightly exceeds the 0.500 threshold and does not by itself demonstrate high-quality 54-qubit computation. The GHZ stateGHZ stateGreenberger–Horne–Zeilinger State / GHZ StateAn entangled quantum state of three or more qubits that is a superposition of the state in which all qubits are 0 and the state in which all qubits are 1. It is used as a representative indicator to verify entanglement spanning multiple qubits.QI NoteThe scale at which GHZ states can be generated is one indicator of a quantum computer’s multi-qubit control performance. A fidelity exceeding 0.5 constitutes evidence of genuine multipartite entanglement, but this does not directly demonstrate practical performance in quantum computation or quantum advantage. is a fundamental benchmark for large-scale entanglement, but it does not directly indicate performance on general quantum algorithms.

IQM Emerald is a 54-physical-qubit superconducting quantum processorquantum processorQuantum Processor / Quantum Processor / Quantum Processing Unit / QPUThe central part of the hardware that houses qubits and performs quantum computational operations such as quantum gates and measurements.QI NoteThe performance of a QPU cannot be judged by the number of qubits alone. Gate fidelity, connectivity, speed, error rates, and other factors must be considered together. (QPU) offered via the cloud since 2025. IQM’s system products include Radiance, which targets NISQNISQNoisy Intermediate-Scale Quantum / NISQA term for quantum devices of roughly tens to thousands of qubits that include noise and do not have sufficient error correction, or for the technological stage they represent.QI NoteIt is not a classification defined by a strict qubit count. Because it broadly refers to devices prior to FTQC, one needs to examine specific error rates and the circuits that can be executed. computing, and the next-generation Halocene, which emphasizes quantum error correctionquantum error correction量子誤り訂正 / Quantum Error Correction / QECA technique that distributes information across multiple physical qubits and detects and corrects errors without directly disturbing the quantum state.QI NoteSimply implementing it does not automatically provide practical fault tolerance. What matters is whether the logical error rate is improved relative to the physical error rate.. Emerald sits in the same 54-qubit class as Radiance; this result stems from calibration, control, and circuit-optimization improvements on the existing QPU rather than from the new Halocene architecture.

One point to note is that fidelity was 0.515 at 40 qubits without readout-error mitigation (REM), whereas the 54-qubit figure of 0.516 is reported after applying REM. Because the measurement conditions differ, one cannot conclude that fidelity was maintained simply by increasing the qubit count. The margin above the threshold is only 0.016, so verification that accounts for statistical uncertainty is important.

On the other hand, automatic optimization of state preparation based on gate fidelitygate fidelityGate Fidelity / Gate Fidelity / Quantum Gate FidelityA measure of accuracy that indicates how closely a quantum gate operation was performed compared to the ideal operation.QI NoteHigher is generally better, but values depend on the measurement method and differ between single-qubit and two-qubit gates. When comparing, also check the evaluation conditions. and idle time is a practically meaningful improvement. Still, this demonstration used a specific GHZ circuit across all 54 qubits and does not guarantee improved performance for general workloads across the processor. Future evaluation should focus on 54-qubit fidelity without REM, performance on more complex circuits, and results for practical quantum algorithms.

NETWORKExplore IQM’s industry network →

Related articles

• D-Wave launches beta of gate-model quantum simulator, ahead of dual-rail hardware
• IQM to deliver 5-qubit “Spark” to Eldorado in Brazil — first South American deployment
• Toyo Technica to install two IQM quantum computers, aiming to set up G-QuAT and domestic go-to-market strategy

Source

Read the original press release