# Superconducting Quantum Processors: State of the Field (October 2026)

Research dossier · v1 · updated 2026-10-30 · 3,992 words · 38 sources · 28 claims · verification: verified

An expert briefing on superconducting quantum processors as of late October 2026: transmon, fluxonium and bosonic (GKP and cat) qubits; coherence, two-qubit gate and readout fidelity; surface-code memories and their error-suppression factor; beyond-classical experiments; and the wiring and control limits on scaling. The main takeaway is that a superconducting surface-code memory now outlives its best physical qubit, with an error-suppression factor of about 2.1 per distance step, while open problems include rare correlated errors and the control wiring that very large machines will need.

## Contents

- Executive summary
- Background and core concepts
- Timeline of key milestones
- State of the art
  - Transmons and coherence
  - Fluxonium
  - Two-qubit gates, crosstalk and ZZ suppression
  - Readout
  - Error correction
  - Beyond-classical and algorithmic demonstrations
  - Quantitative benchmarks
- Open problems and active debates
- Major programs and players
- Outlook: what to watch (next 12-18 months)
- Key papers
- Glossary

## Sample findings

- Google's distance-7 surface-code memory on 101 qubits logged 0.143% +/- 0.003% logical error per 1.1 us cycle, with error suppression Lambda = 2.14 +/- 0.02 per distance step and a logical lifetime 2.4 +/- 0.3 times its best physical qubit.
- In repetition codes run up to distance 29, logical performance is limited by rare correlated error events, about once per hour or once per 3 x 10^9 cycles.

## Get the full dossier

GET https://space-kitty.com/api/v1/dossiers/superconducting-qubits costs $0.20 via x402 (USDC on Base Sepolia (testnet)). Send `Accept: text/markdown` for Markdown or `application/json` for structured data (claims with citations, timeline, benchmarks, open problems, glossary, bibliography).
---
Space Kitty Archive · https://space-kitty.com · API: https://space-kitty.com/api/v1 · MCP: https://space-kitty.com/mcp · Premium: $0.20/request via x402 (Base Sepolia (testnet)). Metadata: arXiv (CC0), OpenAlex (CC0), Europe PMC (CC BY/CC0 works), ClinicalTrials.gov.