Drag-and-drop quantum circuit construction with live state evolution
A quantum circuit is the program of a quantum computer: gates placed on qubit wires, read left to right. Build one and run it.
Pick a gate from the palette and click the grid to place it; click a placed gate to remove it. Put H on q₀, then a CNOT, and watch the entanglement indicator light up.
Select a gate, then click on the circuit grid to place it. Click an existing gate to remove it. CNOT uses the clicked wire as control and the other wire as target.
A quantum circuit is a sequence of gates applied to qubits — it's the "program" of a quantum computer. Unlike classical circuits that carry electrical signals, quantum circuits manipulate probability amplitudes. Every quantum algorithm — from Grover's search to Shor's factoring — is expressed as a circuit.
Build circuits by placing gates on qubit wires, step through execution to see the state evolve, and explore famous circuits that demonstrate the power of quantum computation.
Select a gate from the palette and click on the circuit grid to place it. The state vector updates in real-time as you build. Try placing H on q₀ then CNOT to create a Bell state — watch the entanglement indicator light up! Click any placed gate to remove it.
Building Intuition: Start with H to create superposition, then use CNOT to entangle. Notice how single-qubit gates never create entanglement — you need two-qubit gates.
Circuit Order: Gates execute left-to-right (t0, t1, t2...). Each column is one time step. The output state depends on the order of gates — quantum operations don't commute!
Select a pre-built circuit and step forward one gate at a time. Watch the amplitudes shift and interfere at each step.
Watch the quantum state evolve one gate at a time. Select a pre-built circuit and step forward to see exactly how each gate transforms the state vector. This is how quantum computation actually works — amplitudes flow and interfere at each step.
Click through the Bell state, GHZ, superdense coding, teleportation and phase kickback circuits, and compare the states each one produces.
These circuits are the building blocks of quantum information science. The Bell state circuit creates entanglement. The GHZ circuit entangles three qubits. Superdense coding sends two classical bits using one qubit. Quantum teleportation transfers a state without moving a qubit. Phase kickback is the engine behind every quantum algorithm.
Phase kickback — The mechanism behind quantum speedups: eigenvalues of unitaries kick back as phases on control qubits
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