Cirq

Cirq is an open-source framework for noisy intermediate scale quantum (NISQ) computers.^[1]

History[]

Cirq was developed by the Google AI Quantum Team, and the public alpha was announced at the International Workshop on Quantum Software and Quantum Machine Learning on July 18, 2018.^[2] A demo by QC Ware showed an implementation of QAOA solving an example of the maximum cut problem being solved on a Cirq simulator.^[3]

Usage[]

Quantum programs in Cirq are represented by "Circuit" and "Schedule" where "Circuit" represents a Quantum circuit and "Schedule" represents a Quantum circuit with timing information. ^[4] The programs can be executed on local simulators. ^[5]

The following example shows how to create and measure a Bell state in Cirq.

import cirq

# Pick qubits
qubit0 = cirq.GridQubit(0, 0)
qubit1 = cirq.GridQubit(0, 1)

# Create a circuit
circuit = cirq.Circuit.from_ops(
    cirq.H(qubit0),
    cirq.CNOT(qubit0, qubit1),
    cirq.measure(qubit0, key='m0'),
    cirq.measure(qubit1, key='m1')
)

Printing the circuit displays its diagram

print(circuit)
# prints
# (0, 0): ───H───@───M('m0')───
#                │
# (0, 1): ───────X───M('m1')───

Simulating the circuit repeatedly shows that the measurements of the qubits are correlated.

simulator = cirq.Simulator()
result = simulator.run(circuit, repetitions=5)
print(result)
# prints
# m0=11010
# m1=11010

Projects[]

OpenFermion-Cirq[]

OpenFermion-Cirq is a library that compiles quantum simulation algorithms to Cirq. ^[2]

References[]