Bernstein analyst Gautam Chhugani argues quantum is a manageable upgrade cycle, not an existential risk.

The analyst commented: "Quantum is manageable upgrade cycle not an existential risk; The emergence of cryptographically relevant quantum computers (CRQCs) poses a known challenge to Bitcoin and the broader crypto ecosystem, along with all applications utilizing modern cryptographic techniques. Recent breakthroughs (such as Google Quantum AI's paper demonstrating a ~20x reduction in qubit requirements) seem to have accelerated the timeline, as the challenge is no longer “a decade away” as thought earlier. However, the scaling from 10s of logical qubits to 1000s of logical qubits is not trivial and involves multi-dimensional breakthroughs - quantum timelines may still be optimistic than reality. Nonetheless, Bitcoin and crypto protocols should prepare for post quantum security, and we expect adequate time (3-5 years) for protocols to evolve. Besides commercial scalability and cost considerations (several billions if not hundreds of billions) imply adequate time to transition. Further, resourceful commercial players (Strategy, Blackrock, Fidelity et al) are involved with Bitcoin, and we expect them to play a constructive role in security.

What is Quantum Computing, and why is it a challenge? Quantum computers (QC) run on qubits (can exhibit multiple states between 0 and 1 due to a property called superposition) instead of classical bits (0 and 1 only), allowing them to run Shor’s algorithm to break most common (and currently, secure) encryption types - RSA and Elliptic Curve, which depend on complex math problems. A common analogy is a lock, where classical computers try every possible combination which is time-taking, QCs are like ghost breakers that try multiple variations in parallel and break the lock faster. However, QCs face several multidimensional challenges, in terms of scale, error correction, cycle time, calibration, and manufacturability. The research from Google is a reminder that the requirements are constantly being brought down as hardware ramps up, so it does necessitate Bitcoin core group to consider the risks.

Is crypto at risk? The risk is neither existential, nor novel, and also not limited to crypto. Everything from financial services, military, healthcare, etc. will also face the challenge. The threat is highest for ~1.7 Mn BTC in legacy wallets (Satoshi-era) while for newer encryption protocols, chains and RWAs it is limited to some unsafe practices that can be mitigated, and their management is actively being discussed in detail in the blockchain community. Bitcoin mining has no realistic risk from QCs based on Shor’s algorithm as SHA encryption used in mining is quantum safe - several millions of years even after recent improvements, including Grover’s algorithm.

Post quantum crypto: Crypto networks have clear, technically viable paths already underway with PQC (Post Quantum Cryptography) replacing elliptic curve and RSA schemes with algorithms based on lattice/hash based ones believed to be quantum resistant. For Bitcoin and adjacent ecosystem, it will not be an emergency overhaul and more of a protocol evolution with wallet upgrades, address reuse mitigation, key rotation etc. We think that the quantum should be seen as a medium to long term system upgrade cycle rather than a risk."