Getting Started with Cirq

Getting Started with Cirq

This is the canonical first program for getting started with Cirq, the quantum-computing equivalent of a "hello world". It constructs a single-qubit circuit, applies a square-root-of-NOT gate (X0.5), measures the qubit, and runs the circuit on Cirq's built-in state-vector simulator for a number of repetitions. The example walks through the core Cirq workflow end to end: allocating a named qubit on a grid, assembling a sequence of operations into a Circuit object, appending a measurement, instantiating a Simulator, and reading back the histogram of measurement outcomes. Because the X0.5 gate places the qubit into an equal superposition before measurement, repeated runs return a roughly balanced mix of 0 and 1 results, illustrating quantum randomness in the simplest possible setting. It is intentionally minimal, so newcomers can see how qubits, gates, circuits, simulation, and measurement fit together without the distraction of a full algorithm, making it an ideal starting point before moving on to teleportation, the quantum Fourier transform, or any of the named algorithms in this collection.

Run it

pip install -r requirements.txt
python hello_qubit.py

Source and license

Imported from examples/hello_qubit.py in quantumlib/Cirq at v1.6.1, under the Apache License 2.0. Original authors: The Cirq Developers. The upstream LICENSE is included alongside this example.