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Google has reported a significant improvement in error reduction when preparing quantum states using its Willow chip. This progress tackles a major engineering hurdle in the potential future threat to Bitcoin wallets.
What Happened
The Willow chip achieved a 40-fold reduction in errors during the preparation of ‘magic states.’ These states are essential for quantum calculations that could, in theory, break Bitcoin wallet encryption.
The result was published in Science this week. It focuses on a critical step in quantum computing—not the full machine, but the process of preparing stable, usable states.
While the chip isn’t a full quantum computer, its ability to produce reliable states is a foundational step for any future quantum system designed to run Shor’s algorithm.
How It Works: Magic States and Error Correction
Quantum computers use qubits to store information. These qubits are fragile and easily disturbed by heat, vibration, or signals.
To protect against errors, engineers group multiple physical qubits into logical qubits. These groups can detect and correct errors, making computation more reliable.
Operations require special ‘magic states’—like fuel in a machine. Each state is consumed when used. For long calculations like Shor’s algorithm, the machine must continuously produce these states.
Older methods required many hardware resources and repeated attempts. Google’s ‘cultivation’ method improves this by quickly checking each attempt and discarding flawed ones. Only clean states are kept and used.
Why It Matters: The Theoretical Threat to Bitcoin
Bitcoin relies on the difficulty of reversing a public key into a private key. The private key is a secret number used to sign transactions.
Public keys are revealed when a transaction occurs. Anyone with access to that key could, in theory, recover the private key and sign transactions as the owner.
Mathematician Peter Shor published an algorithm in 1994 that could factor large numbers exponentially faster than classical computers. This could allow an attacker to break Bitcoin’s key encryption.
No quantum computer has yet run Shor’s algorithm on real data. But progress in error reduction brings the theoretical possibility closer to reality.
Old Coins and Market Activity: A Signal of Growing Concern
Some of Bitcoin’s oldest coins have had their public keys exposed since mining. These keys remain visible on the blockchain.
Old coins have been moving recently. On Oct. 7, 100.02 BTC moved after 16 years. In August, 553.59 BTC shifted from inactive wallets.
These moves don’t prove holders are reacting to quantum threats. They could also reflect wallet changes, reorganizations, or selling plans.
How It Fits with Earlier Research
In March, Google estimated a quantum computer with fewer than 500,000 physical qubits could break Bitcoin and Ethereum wallet encryption.
That estimate assumed efficient magic state production. The Willow experiment tests that assumption directly.
While the March paper outlined the computational load, Willow improves the feasibility of producing those states. But the gains cannot be simply multiplied. Each stage operates under different constraints.
Limitations and Open Questions
The experiment achieved 99.99% fidelity only for states that passed inspection. About 8% of attempts succeeded.
For every 100 tries, only eight produced usable states. This shows the method is not yet scalable to full attack levels.
Scaling to produce thousands of magic states per second over long durations remains unproven. Real-time error correction and state maintenance during long operations are still under development.
What to Watch Next
Researchers must scale the cultivation method to larger systems. They must also maintain state integrity over extended operations.
Efforts to develop quantum-resistant cryptography—like post-quantum algorithms—may grow as the threat becomes more tangible. These could include new standards, secure protocols, and better key management.
While this is a major technical advance, it does not mean Bitcoin is at immediate risk. The full attack remains theoretical, dependent on many unproven hardware and software developments.
Source: Coindesk
