Work

How to write a simulator for quantum circuits from scratch: A tutorial

Year: 2026

Type: article

Abstract: We guide a competent programmer through the programming of a quantum circuit simulator, supporting quantum logic gates with arbitrary control qubits on 20+ qubits, assuming no previous knowledge of quantum computing. We explain qubit-wise multiplication for updating the state vector; how to compute partial traces on arbitrary subsets of qubits to find reduced density matrices; and computing qubit phase and purity. A sample implementation in JavaScript is provided, which also demonstrates how to compute von Neumann entropy, concurrence (to quantify entanglement), and magic, with source code much smaller and easier to study than other popular software packages.

Source: SciPost Physics Lecture Notes

DOI: 10.21468/scipostphyslectnotes.131

Authors: Michael J. McGuffin, Jean-Marc Robert, Kazuki Ikeda

Institutions: École de Technologie Supérieure, University of Massachusetts Boston

Language: English

Topic: Quantum Computing Algorithms and Architecture

Subfield: Artificial Intelligence

Field: Computer Science

Domain: Physical Sciences

Open Access status: diamond

Funders: National Science Foundation, Natural Sciences and Engineering Research Council of Canada

Award: ExpandQISE: Track 2: EQUIP-UMB-Expand Quantum Information Programs at UMass Boston