Cirq is a Python library for writing, manipulating, and optimizing quantum circuits and running them against quantum computers and simulators.

Installation

Follow these instructions.

Hello Qubit

A simple example to get you up and running:

import cirq

# Pick a qubit.
qubit = cirq.GridQubit(0, 0)

# Create a circuit
circuit = cirq.Circuit.from_ops(
    cirq.X(qubit)**0.5,  # Square root of NOT.
    cirq.measure(qubit, key='m')  # Measurement.
)
print("Circuit:")
print(circuit)

# Simulate the circuit several times.
simulator = cirq.google.XmonSimulator()
result = simulator.run(circuit, repetitions=20)
print("Results:")
print(result)

Example output:

Circuit:
(0, 0): ───X^0.5───M('m')───
Results:
m=11000111111011001000

Documentation

See here or jump into the tutorial.

Contributing

We welcome contributions. Please follow these guidelines.

We use Github issues for tracking requests and bugs. Please post questions to the Quantum Computing Stack Exchange with a 'cirq' tag.

See Also

For those interested in using quantum computers to solve problems in chemistry and materials science, we encourage exploring OpenFermion and its sister library for compiling quantum simulation algorithms in Cirq, OpenFermion-Cirq.

Disclaimers

Cirq is currently in alpha. We are still making breaking changes, and we will break your code when we make new releases. We recommend that you pin a specific version of cirq in requirements.txt files, and periodically bump to the latest release. That way you have control over when a breaking change affects you.

Cirq is not an official Google product. Copyright 2018 The Cirq Developers