README.md

Quantum circuit simulator in Swift

Usage

Circuit

Check code in Circuit.playground.

Circuit with noise

import SwiftQuantumComputing // for macOS
//: 1. Compose a list of quantum gates & noises
let quantumOperators: [QuantumOperatorConvertible] = [
    Gate.hadamard(target: 0),
    Noise.bitFlip(probability: 0.35, target: 0),
    Gate.phaseShift(radians: 0.25, target: 2),
    Noise.phaseDamping(probability: 0.75, target: 2),
    Gate.controlled(gate: .hadamard(target: 1), controls: [2, 0]),
    Noise.bitFlip(probability: 0.8, target: 1)
]
//: 2. Build a quantum circuit with noise using the list
let circuit = MainNoiseCircuitFactory().makeNoiseCircuit(quantumOperators: quantumOperators)
//: 3. Use the quantum circuit with noise
let result = try circuit.densityMatrix().get()
print("Density matrix: \(result)\n")
print("Probabilities: \(result.probabilities())\n")

Check code in NoiseCircuit.playground.

Performance

~/SwiftQuantumComputing % swift run sqc-measure-performance

Run this application to check the performance of this simulator in your computer. Execute swift run sqc-measure-performance -h to see all available options.

Check code in SQCMeasurePerformance/main.swift.

Algorithms

• Use a genetic algorithm to automatically generate a quantum circuit - Check example in Genetic.playground.
• Two-level decomposition: Decompose any gate into an equivalent sequence of not gates and fully controlled phase shifts, z-rotations, y-rotations & not gates - Check example in TwoLevelDecomposition.playground.

Other algorithms

• Euclidean Algorithm: Find greatest common divisor of two integers - Check example in EuclideanAlgorithm.playground.
• Continued Fractions: Find an approximation to a given rational number - Check example in ContinuedFractions.playground.
• Gaussian Elimination: Solve a system of XOR equations - Check example in XorGaussianElimination.playground.

More examples

• Bernstein–Vazirani algorithm - Check code in BernsteinVaziraniAlgorithm.playground.
• Deutsch's algorithm - Check code in DeutschAlgorithm.playground.
• Deutsch-Jozsa algorithm - Check code in DeutschJozsaAlgorithm.playground.
• Grover's algorithm - Check code in GroverAlgorithm.playground.
• Shor's Algorithm - Check code in ShorAlgorithm.playground.
• Simon's periodicity algorithm - Check code in SimonPeriodicityAlgorithm.playground.

Documentation

Documentation for the project can be found here.

References

• Amazon Braket Default Simulator
• Automatic Quantum Computer Programming: A Genetic Programming Approach
• Continued Fractions and the Euclidean Algorithm
• Decomposition of unitary matrices and quantum gates
• Decomposition of unitary matrix into quantum gates
• IBM Qiskit
• qHiPSTER: The Quantum High Performance Software Testing Environment
• Quantum Computing for Computer Scientists
• Shor's Quantum Factoring Algorithm

SwiftPM dependencies

• CBLAS-Linux (only for Linux)
• CLapacke-Linux (only for Linux)
• Swift Argument Parser
• Swift Numerics

Linux

This package depends on BLAS & LAPACK if running on Linux, more exactly, Ubuntu.

These dependencies are reflected in Package.swift with:

• CBLAS-Linux, which in turn expects to find: /usr/include/x86_64-linux-gnu/cblas-netlib.h
• CLapacke-Linux, which in turn expects to find: /usr/include/lapacke.h

So, after installing BLAS & LAPACK (in case they are not already there):

sudo apt-get install libblas-dev liblapacke-dev

Check cblas-netlib.h & lapacke.h are in the expected locations.