Architecture Glossary

This glossary defines key terms used throughout the PRISM-Q architecture and documentation.

Terms

Backend A simulation strategy implementing the Backend trait (e.g., statevector, stabilizer, MPS). Backends are swappable and selected automatically or explicitly per circuit.

Clifford A class of quantum gates (H, S, CNOT, etc.) that can be simulated efficiently on stabilizer tableaus in O(n²) time.

Count A frequency histogram of measured bitstrings across multiple shots, returned by simulate(circuit).seed(seed).sample_counts(shots).

Fusion The pre-simulation optimization pipeline that merges, cancels, and reorders gates to reduce execution cost.

Marginal Per-qubit probabilities of measuring |1⟩, extracted without computing the full multi-qubit distribution.

MPS (Matrix Product State) A tensor-network backend that stores the quantum state as a chain of rank-3 tensors with bounded bond dimension, trading exactness for polynomial memory.

Noise model A collection of probabilistic error channels (e.g., depolarizing noise) applied during noisy multi-shot simulation.

OpenQASM An assembly-like language for describing quantum circuits. PRISM-Q parses a practical subset of OpenQASM 3.0.

Shot A single execution of a quantum circuit from initialization to measurement, producing one bitstring sample.

State vector A flat vector of 2^n complex amplitudes representing the full quantum state, used by the statevector backend.

Stabilizer A representation of a Clifford state as a bit-packed tableau of Pauli generators, enabling simulation of thousands of qubits.

Tensor network A backend that represents gates as tensors and defers contraction until measurement or probability extraction.