swapGate

Swap gate

Since R2023a

Installation Required: This functionality requires MATLAB Support Package for Quantum Computing.

Syntax

g = swapGate(targetQubit1,targetQubit2)

Description

g = swapGate(targetQubit1,targetQubit2) applies a swap gate that swaps the states of two target qubits and returns a quantum.gate.SimpleGate object.

• If targetQubit1 and targetQubit2 are vectors of the same length, then swapGate returns a column vector of gates, where g(i) represents a swap gate applied to two target qubits with indices targetQubit1(i) and targetQubit2(i).

• If either targetQubit1 or targetQubit2 is a scalar, and the other input is a vector, then MATLAB^® expands the scalar to match the size of the vector input.

• The qubit indices in each element pair of targetQubit1 and targetQubit2 must not be the same.

Examples

Swap Gate and Its Matrix Representation

Create a swap gate that acts on two target qubits with indices 1 and 2.

g = swapGate(1,2)

g = 

  SimpleGate with properties:

             Type: "swap"
    ControlQubits: [1×0 double]
     TargetQubits: [1 2]
           Angles: [1×0 double]

Get the matrix representation of the gate.

M = getMatrix(g)

M =

     1     0     0     0
     0     0     1     0
     0     1     0     0
     0     0     0     1

Array of Swap Gates

Create an array of three swap gates. The first gate acts on target qubits 1 and 2, the next gate acts on target qubits 2 and 3, and the final gate acts on target qubits 3 and 4.

g = swapGate(1:3,2:4)

g = 

  3×1 SimpleGate array with gates:

    Id   Gate   Control   Target
     1   swap             [1,2] 
     2   swap             [2,3] 
     3   swap             [3,4] 

Input Arguments

targetQubit1 — First target qubit of gate

positive integer scalar | positive integer vector

First target qubit of the gate, specified as a positive integer scalar index or vector of qubit indices.

Example: 1

Example: 3:5

targetQubit2 — Second target qubit of gate

positive integer scalar | positive integer vector

Second target qubit of the gate, specified as a positive integer scalar index or vector of qubit indices.

Example: 2

Example: 6:8

More About

Matrix Representation of Swap Gate

The matrix representation of a swap gate applied to two target qubits is

$$\left[\begin{array}{cccc}1& 0& 0& 0\\ 0& 0& 1& 0\\ 0& 1& 0& 0\\ 0& 0& 0& 1\end{array}\right].$$

Version History

Introduced in R2023a