Largest quantum processors available:
Google Willow: 105 qubits (December 2024)
Atom Computing: 1,180 qubits (October 2023) - though these are physical qubits with high error rates
IBM roadmap: Targeting 1,060 qubits by 2027 (missed their 2025 goal of 1,092 qubits)
Infleqtion UK: 100-qubit operational system (March 2026)
Important distinction - Physical vs. Logical Qubits:
Physical qubits: The actual quantum bits in the hardware (we have 100-1,180 of these today)
Logical qubits: Error-corrected qubits needed for practical computation
The gap: Approximately 1,000 physical qubits needed for 1 logical qubit due to error correction overhead
Cryptographically-Relevant Quantum Computers (CRQCs):
Breaking RSA-2048 requires an estimated ~20 million physical qubits (or ~20,000 logical qubits)
Current systems: 50-1,180 physical qubits (NISQ era - Noisy Intermediate-Scale Quantum)
We're roughly 3 orders of magnitude away from crypto-breaking quantum computers
Timeline estimates:
Mid-2030s: Quantum systems with thousands of stable, error-corrected qubits expected
Unknown: Exact date when CRQCs will exist (hence the "harvest now, decrypt later" concern)