SwapGate

class qiskit.circuit.library.SwapGate(label=None)

Bases: Gate

The SWAP gate.

This is a symmetric and Clifford gate.

Can be applied to a QuantumCircuit with the swap() method.

Circuit symbol:

q_0: ─X─
      │
q_1: ─X─

Matrix Representation:

\[\begin{split}SWAP = \begin{pmatrix} 1 & 0 & 0 & 0 \\ 0 & 0 & 1 & 0 \\ 0 & 1 & 0 & 0 \\ 0 & 0 & 0 & 1 \end{pmatrix}\end{split}\]

The gate is equivalent to a state swap and is a classical logic gate.

\[|a, b\rangle \rightarrow |b, a\rangle\]

Create new SWAP gate.

Attributes

condition_bits

Get Clbits in condition.

decompositions

Get the decompositions of the instruction from the SessionEquivalenceLibrary.

definition

Return definition in terms of other basic gates.

duration

Get the duration.

label

Return instruction label

name

Return the name.

num_clbits

Return the number of clbits.

num_qubits

Return the number of qubits.

params

return instruction params.

unit

Get the time unit of duration.

Methods

control(num_ctrl_qubits=1, label=None, ctrl_state=None)

Return a (multi-)controlled-SWAP gate.

One control returns a CSWAP (Fredkin) gate.

Parameters:

• num_ctrl_qubits (int) -- number of control qubits.

• label (str or None) -- An optional label for the gate [Default: None]

• ctrl_state (int or str or None) -- control state expressed as integer, string (e.g. '110'), or None. If None, use all 1s.

Returns:

controlled version of this gate.

Return type:

ControlledGate

inverse()

Return inverse Swap gate (itself).