What is the largest quantum computer by qubit count?
As of March 2026, the largest quantum computer by physical qubit count has 1,180 qubits, a neutral atom device announced in October 2023. Per-platform records: Neutral Atom 1,180, Superconducting 1,121, Trapped-Ion 98. Physical qubits are not logical qubits: with error correction, one logical qubit costs 32–3,747 physical qubits depending on the code and distance.
Physical vs logical qubits
Raw qubit counts overstate useful capacity. Useful fault-tolerant computation needs error-corrected logical qubits, each built from many physical qubits, see the overhead breakdown below. Dividing today's record count (1,180) by even the most efficient demonstrated code's overhead (~32 physical per logical for the Gross code) yields at most ~37 logical qubits, far short of the 1,399 needed for RSA-2048.
Qubit counts double roughly every 1.5 years (neutral atom), 1.4 years (superconducting), 2.3 years (trapped-ion) on log-linear fits of the record series.
Compute it yourself
Every number on this page is computed from the same open model that powers the interactive calculator and the MCP server for AI assistants.
GET https://www.quantum-expectations.com/api/fit-historic-series?seriesType=qubit-count&hardwareType=Superconducting