Quantum Circuit Runner Guide for 2026

What Quantum Circuit Runner does

Quantum Circuit Runner gives you a small circuit workspace inside Chrome or Edge. Add single-qubit gates or CNOT operations, choose a shot count, and view measured bitstrings. Simulation happens in browser memory. No account, API key, network request, or paid hardware access is involved.

Set initial qubit states

Each qubit starts in computational basis state 0 by default. Use Initial state controls to set q0, q1, or q2 to 0 or 1 before running. Set q0 to 1, add H q0, and inspect the resulting distribution from a different starting basis state. Starting in |1> also helps you test X, phase, and entanglement circuits from another input.

Install the extension

Open the extension folder in the FreeQuantumComputing repository, then open chrome://extensions or edge://extensions. Enable Developer mode, choose Load unpacked, and select the extension folder. Pin Quantum Circuit Runner from your browser toolbar, then open the popup.

• →Extension source on GitHub : manifest, popup, simulator, and self-check

Build a Bell state

Choose Bell state from Prebuilt circuit and click Load. The extension sets Qubits to 2 and loads H q0 followed by CNOT q0 → q1. Click Run circuit. Results usually show 00 and 11 in near-equal proportions. H creates a superposition on q0, and CNOT correlates q1 with q0. This pattern introduces superposition, entanglement, and measurement in one short circuit.

• →Bell state walkthrough : run the same idea with a quantum SDK

Add gates and choose targets

Use the Gate menu to add H, X, Y, Z, S, or T to one target qubit. H changes a basis state into a balanced superposition. X flips 0 and 1. Y and Z add different rotations and phase changes. S and T add phase rotations. CNOT uses one control and one target, then flips the target when the control is 1. Remove any operation from the circuit list before running again.

• →Quantum gates explained : see each gate's matrix and effect

Understand shots and results

Each shot measures the final state once. A single shot gives one bitstring, while many shots form a distribution. Bitstrings show q0 first, so 10 means q0 measured 1 and q1 measured 0. Raise the shot count for a steadier estimate of each outcome probability.

Know simulator limits

The extension uses ideal state-vector math for up to three qubits. Results exclude gate noise, readout errors, decoherence, hardware connectivity, queue time, and calibration drift. Use the simulator to learn circuit logic and expected distributions. Use a real QPU when you need hardware behavior.

• →Run a circuit on real hardware : move from simulation to a free QPU

Continue learning

After your first Bell state, follow the gates guide, then compare simulator output with a noisy hardware run. The learning path adds linear algebra, algorithms, and real-hardware practice in a useful order.

• →Quantum computing learning path : move from first circuit to algorithms
• →Free quantum simulators guide : compare larger local and cloud simulators