# SwapOperator

 Other toolboxes required SwapOperator Produces a unitary operator that swaps two subsystems none PermutationOperatorPermuteSystemsSwapSymmetricProjection Permutations and symmetry of subsystems

SwapOperator is a function that returns a unitary operator that swaps two subsystems. The unitary can be chosen to be full or sparse.

## Syntax

• S = SwapOperator(DIM)
• S = SwapOperator(DIM,SP)

## Argument descriptions

• DIM: A specification of the dimensions of the subsystems that S will act on. DIM can be provided in one of two ways:
• If DIM is a scalar, then both subsystems are assumed to have dimension DIM.
• If the subsystems have unequal dimensions, DIM should be a 1-by-2 vector containing their dimensions.
• SP (optional, default 0): If set equal to 1, the swap operator is sparse. If equal to 0, the swap operator is full.

## Examples

### The standard swap operator

The following code produces the operator that swaps two qubits:

```>> SwapOperator(2)

ans =

1     0     0     0
0     0     1     0
0     1     0     0
0     0     0     1```