Qiskit Spacetime Bridge

quantum-error-correction
circuit-analysis
Outcome/spacetime codes from Clifford circuits, feeding stabilizer structure into the Cayley-codes analysis backend
Published

September 1, 2026

STATUS · Qiskit Ecosystem submission in review · PR #1339 (draft)

What it does

A bridge module implementing the outcome-code construction (Algorithm 1) and the back-cumulant spacetime-code construction from Delfosse & Paetznick, “Spacetime codes of Clifford circuits” (arXiv:2304.05943). It takes a Clifford circuit, slices it through time, and turns the resulting outcome structure into a stabilizer generator matrix.

Where it feeds

The stabilizer generator matrix produced here is the intended input to the Qiskit Cayley Codes CDZ analysis backend — turning a circuit’s spacetime structure into an object that can be checked and analyzed as a CSS code.

Open, and documented as open

CZ/SWAP gates, Algorithm 3 (LDPC sparsification), the logical operators of Proposition 10, and real code-distance computation are not yet implemented. The actual wiring into the qiskit-cayley-codes source is also still pending — right now the two packages are connected by intent, not by code.