China’s 90-Bit Quantum Code Breakthrough: How Close Are We to the ‘Q-Day’ Data Meltdown?
Key takeaways
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Shanghai researchers have cracked a 90-bit RSA integer on a D-Wave Advantage system—the largest quantum factorisation to date.
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The leap smashes the previous 50-bit ceiling and edges the world nearer to the dreaded “Q-Day,” the moment quantum computers can rip through today’s encryption.
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Banks, governments and blockchain networks are being urged to speed up post-quantum cryptography (PQC)migrations as discovery accelerates.
What happened?
Professor Wang Chao and colleagues at Shanghai University have pulled off the first successful factorisation of a 90-bit RSA number using a hybrid workflow that blends classical cryptographic pruning with quantum annealing on D-Wave’s 5,760-qubit Advantage machine.
Until now, experts at Google, IonQ and elsewhere maintained that anything above 80 bits was out of reach for near-term hardware. Wang’s team surpassed that barrier by:
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Recasting RSA factoring as a Closest Vector Problem (CVP).
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Injecting classical lattice-reduction techniques to shrink the search space.
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Exploiting quantum tunnelling to jump out of local minima and hone in on the global solution.
Why 90 bits matters
| Milestone | Year / Lab | Hardware | RSA bits cracked |
|---|---|---|---|
| Lockheed Martin proof-of-concept | 2016 | D-Wave 2000Q | 13 |
| Purdue University demo | 2021 | Ion-trap testbed | 20 |
| Shanghai University (earlier paper) | 2024 | D-Wave Advantage | 50 |
| Shanghai University (new record) | 2025 | D-Wave Advantage | 90 |
A 90-bit key is tiny compared with the 2,048-bit keys shielding online banking, VPNs and e-commerce. But cryptographers track trend lines, not isolated numbers. If the bit length keeps doubling every 12–18 months, triple-digit cracks may arrive well before the decade ends.
The looming “Q-Day”
“Q-Day” shorthand refers to the point when practical quantum computers can decrypt RSA, ECC and other public-key systems in hours rather than millennia. Google’s latest Willow chip still has only 105 physical qubits—far short of the millions Shor’s algorithm needs for RSA-2048—but today’s result shows side-door attacks could get there sooner.
What industries should do now
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Launch PQC migration plans. NIST will finalise quantum-safe standards this year—start pilot deployments early.
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Design for crypto-agility. Build systems that can swap algorithms without forklift upgrades.
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Audit “store-now, decrypt-later” risks. Assume adversaries are harvesting encrypted traffic today for decryption tomorrow.
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Experiment with hybrids. Pair classical lattice-based crypto with quantum-key distribution where practical.
Not a checkmate—yet
Even Wang concedes the feat is “an incremental but essential nudge.” Mainstream RSA still uses 2 K-bit keys—well beyond this milestone. Practical hurdles such as short qubit coherence times, error-correction overhead and the high cost of quantum cloud access remain formidable.
Still, cryptographic history shows every wall eventually crumbles. With China’s leap to 90 bits, the countdown to stronger, quantum-resistant security just ticked noticeably faster.
Bottom line
If your organisation lacks a quantum-readiness roadmap, 2025 is the year to draw one up. The race between code-makers and code-breakers has shifted gears—and the finish line may arrive sooner than anyone expected.
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