The More You Know: Quantum Circuit

Quantum Circuits are used to visualize a prescription of quantum gates acting on a quantum state. They describe the changes of the quantum data as it undergoes successive discrete operations.

The data in a Quantum Circuit is usually encoded in a n-qubit state (other Quantum Circuit models can use m-level quantum systems instead of these 2-level systems) which is set to a known vale, i.e. |000...\rangle. Thus, for every qubit in the circuit a horizontal rail, a wire, is drawn to represent its evolution, time flows from left to right.


Wires in a Quantum Circuit initialized to the n-qubit quantum state |000...\rangle.

Additionally, a Quantum Circuit is built from elementary quantum gates (unitary operations) acting on a fixed number of qubits. Since Quantum Circuits are read from left to right, leftmost gates act first.


Single-qubit and Two-qubit quantum gates in a Quantum Circuit.

Then, a description of the Quantum System consists of

  1. Input: A controlled input n-qubit state.
  2. Evolution: Prescribed sequence of Unitary Single-qubit and Two-qubit logic quantum gates which give the evolution of the initial quantum state.
  3. Output: Readout (measurement) of the state of the n qubits.

Go to the Dictionary of Quantum Information and Quantum Computation.


Quantum Circuits where drawn using this LaTeX package.

 All text copyright © Marco Vinicio Sebastian Cerezo de la Roca.

Licencia Creative Commons
The More You Know: Quantum Circuit por Marco Vinicio Sebastian Cerezo de la Roca se distribuye bajo una Licencia Creative Commons Atribución-NoComercial-CompartirIgual 4.0 Internacional.


About marcocerezo

I'm Marco Cerezo, I have a Ph.D in Physics and I'm currently a Postdoctoral Research Associate at Los Alamos National Laboratory in New Mexico, USA. My main fields of study are Quantum Information, Quantum Computing and Condensed Matter. Currently I'm working to develop novel quantum algorithms which can be useful in near-term quantum devices.
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